Yesterday was the day we talked about dinosaurs and pterosaurs in Historical Geology. Accordingly, I dressed for the occasion:

(That is not me, by the way.) The t-shirt is by the very cool company Squidfire. I recommend you check out this design and their many other cool images on cool clothing at their website. Lily bought me this one - a gift much appreciated!

Labels: dinosaurs, fossils, gear, teaching

First one to identify this animal* (photographed with my new microscope) wins a GEOLOGY ROCKS bumper sticker... Width of photo is about 2 cm.


* Note, not the entire animal is shown.

Labels: contest, fossils

PALEONTOLOGICAL SOCIETY OF WASHINGTON

Maryland in the Miocene: Paleoenvironmental History of the Calvert Cliffs
Susan Kidwell, Williams Rainey Harper Professor of Geology
Department of Geophysical Sciences, University of Chicago

Wednesday, Sept. 16, 2009
7:00 p.m., in the Cooper Room, National Museum of Natural History (10th St. and Constitution Ave. in NW Washington, DC)

Meet in the Constitution Avenue lobby at 5:00 p.m. if you wish to join the PSW members for dinner at the "Elephant and Castle," NW corner of 12th & Penna. Ave., NW

Non-Smithsonian visitors will be escorted to the Cooper Room at 6:30 and 6:55 p.m.

Labels: dc, fossils, maryland, meetings, miocene, psw, smithsonian

All photos in this post by Rockies student Charlie Corrick.

Talking S-folds, vergence, and Pumpelly's Rule in the Bridger Range:


Hiking uphill and down-sequence in the Bridger Range:


Describing the Kootenai Formation:


Jared gets eaten by Big Mike:


Joel with a few columns of basalt:


Post-M.O.R.-tour, with the guide:


Victoria and a Triceratops horn:


Group at M.O.R., with Tyrannosaurus for scale:


Calcified bat, Lewis & Clark Caverns:


Inside the cave:


Beartooth Plateau:


Amanda enjoys the view:


Camp at Pebble Creek in Yellowstone:


Watching for wolves, Yellowstone:


Bison:


Obsidian at Obsidian Cliff:


Longhorned beetle that landed on our geologic map of Yellowstone:


More to come...

Labels: arthropods, dinosaurs, fossils, glacial landforms, mammals, montana, wyoming, yellowstone

Yesterday, I asked you to see what you see here:


And today, I shall tell you what I saw...

Here's what it reminds me of:

...An Olenellid trilobite (slightly deformed)!

Here, I'll sketch it for you:


Garry Hayes came closest to my vision by suggesting the foam pattern resembled Marella splendens, Walcott's "lace crab" of the Burgess Shale.

Labels: art, arthropods, contest, fossils, structure

Here's some images from my first post-master's-post-master's graduate class: "Bahama Montana," Dave Lageson's one-credit examination of carbonate sedimentology with a particular focus on some interesting features in the Bridger Range: Waulsortian-type bioherms. This field trip was on my fourth day in Montana this summer, following a two-hour lecture the previous evening. Unfortunately, the road to Fairy Lake still wasn't totally open, which meant that we had to add an additional three miles each way to our hike, which meant we didn't get to examine the bioherms themselves at close range. Oh well; next year perhaps...

The class hiking up to the summit of Sacagawea Peak:

(The green stripe on the left/west may look familiar from the satellite image I shared yesterday.)

Sacagawea Cirque, not looking especially "Death Cirque"-like* today:


The view south from Sacagawea Peak:


The class, looking east from the summit:


The elusive Waulsortian bioherms, off in the un-logistically-feasible middle distance:

...Interesting that they weather out in high relief, eh?

Dave instructs:






Some cool Columella stromatolites that I hadn't noticed on previous trips up Sacagawea:


More Columella stromatolites:


The class was a good example of how field trips have to be modified to fit local conditions. It was a bummer the road closure added six miles to our hike, but we were able to scour the talus slopes in Sacagawea Cirque for Mississippian fossils like crinoids, brachiopods, corals, and bryozoans. I got some sweet samples of fenestrate bryozoans, but saw none of the spectacular rugose corals that I collected on my first visit to this cirque 2 years earlier.

_________________________________
* The "Death Cirque" moniker is one applied by my NOVA Rockies students the following week, for reasons I shall reveal in due time...

Labels: field trips, fossils, limestone, mississippian, montana, stromatolites

My third day in Montana this summer, Lily and I took a hike in the Bridger Range, going up the west side of the range via Corbly Gulch to a cirque opposite the "usual" route up Sacagawea Peak, which starts at Fairy Lake on the east side, then goes up into Sacagawea Cirque* and south to the peak. Instead, we went up Corbly Gulch and got a whole new look at Bridger stratigraphy. First, orient yourself with this topographic map:



The Fairy Lake route brings you to the ridge crest from the upper right (northeast), wheras the Corbly Gulch route brings you to the same ridge crest from the lower left (southwest). Now take a look at some satellite imagery:



The green line at upper right is the ridge crest; Sacagawea Peak is just off-screen to the right. It will not surprise you to learn that stratigraphic contacts strike NW-SE in this area. The forested left-hand part of the screen is underlain by Mesoproterozoic LaHood Formation, a coarse-grained formation in the Belt Supergroup. Then there's a little gap of grassy area and a thin line of trees atop a light-brownish layer. This is the Cambrian Flathead Sandstone, which is chock-full of interesting sedimentary structures and trace fossils. The prominent light-colored ridge-forming layer traversing the screen from upper left towards lower right is the Cambrian Pilgrim Limestone, which shows "fossil hurricanes" in the form of limestone-chip conglomerates.

Here's some of the trace fossils in the Flathead Sandstone:


Here's a limestone-chip conglomerate from the Pilgrim Limestone, which I interpret as a paleo-hurricane deposit: rip-up clasts from a carbonate bank tumbled and re-deposited together in a big jumble:


We hiked up to the ridge, and peered down into Sacagawea Cirque (getting pummeled by the wind!), but didn't feel like we had sufficient time to attempt summiting Sacagawea, since I had to be back on MSU's campus for an evening session as part of "Bahama Montana" class. More on that tomorrow...

______________________________
* The following week, my Regional Field Geology students proposed to rename Sacagawea Cirque as "Death Cirque," for reasons I will explain in due course...

Labels: cambrian, fossils, limestone, montana, msse, primary structures, proterozoic, sediment

On my first day in Montana this summer, I borrowed Lily's Jeep and set off to look for petrified wood in the Tom Miner Basin, an offshoot of the Paradise Valley (which connects Livingston to Gardiner). Along the way, though, I stopped at Point of Rocks CKCK, and found some nice exposures of the lahar deposits of the Absaroka/Gallatin Volcanic Field. These Eocene-aged extrusions basically consist of a series of lava flows and volcaniclastics interlayered to a substantial thickness.

Here's a map of Point of Rocks:


Here's the view north from Point of Rocks:


Here's some images of the rocks exposed there: poorly-sorted, matrix-supported grey conglomerates that I interpret on the basis of the previous year's field notes to be lahar deposits:




I've got a big fat chunk of this stuff in the NOVA geology lab now -- thanks to Lily for giving that forty pounds of lahar a lift cross-country!

Eventually I made it into the Tom Miner Basin, an area of Forest Service land where there is some petrified wood exposed. There is an interpretive trail where people are specifically asked NOT to collect but of course people collect anyhow, so it's kind of lame, but there are some nice examples of petrified branches and what not, and some nice examples of reverse-graded-bedding in the lahar deposits.

Map of the area where the road ends (at a campsite) and the trail begins:


Reverse graded bedding:


You can climb up above the trail to some exposures of the volcanics which are harder to get to and therefore not picked-over, and with a permit you can collect a fist-sized chunk per person per year.

Here's a couple examples of petrified wood that I saw:




More volcaniclastics, this time showing normal graded bedding (coarse at the bottom, fine at the top):


And on the way out, I saw a nice example of a couple of rugose corals cross-sectioned in a boulder of presumably-Mississippian-aged Madison Group limestone:



It was a nice first day in Montana! More photos to come...

Labels: fossils, igneous, montana, plants, volcano

Bill Parker put up an interesting piece last night on the Chinleana blog about John Muir, the conservationist icon, studying fossils in Arizona's petrified forest (silicified trees in the Chinle Formation badlands). Great historical photos -- Check it out!

Labels: arizona, blogs, environmental, fossils, plants

There's an article on the Burgess Shale and another on inventorying all the plants on Plummers Island (home of the Plummers Island Thrust Fault, between DC and the Billy Goat Trail).

Labels: cambrian, dc, faults, fossils, plants

Yesterday, I took a little tour out along old Route 55 through West Virginia, the road that was replaced by new Route 55, also a source of cool outcrops. My host was Maitland S., a retired gentleman who occasionally takes geology classes at NOVA. We saw a bunch of cool stuff out there, and I'll share it all with you.

First, check out these lovely pyrolusite dendrites:





Pyrolusite is MnO2, and often grows in these beautiful branching forms. It's totally an inorganic process, but the visual similarity to botanical branching makes pyrolusite dendrites a particularly insidious form of pseudofossil. Here, it's growing on limestone, presumably the Devonian Helderberg Group -- though I'll have to check on that to be sure.

Labels: field trips, fossils, minerals, valley and ridge

These days, I'm busy getting things organized for my upcoming Regional Field Geology of the Northern Rockies class -- held next month in Montana and Wyoming. I'm taking the students to two new places that I've never been before, and so a lot of my prep time is learning more about those sites. One is Specimen Ridge in Yellowstone, where there are some petrified trees.

In researching Specimen Ridge, I came across the photos of thorton_3041, who posted an album of images online at Webshots. Look at this beautiful detail!



You can see the tree's rings in gorgeous detail, as well as the silica which filled in a rip (a dessication crack perhaps) in amorphous white, unconstrained by cell walls. My favorite is that little chunk of wood at the bottom, rotating into the void space like a xenolith stoping into a pluton. Check out Thorton's full album! I can't wait to see these trees myself this summer!

Labels: fossils, plants, wyoming, yellowstone

I saw Ray Stanford, an enthusiastic amateur paleontologist, speak last month at a meeting of the Paleontological Society of Washington.

It was my first PSW meeting, and I got a warm welcome from PSW president and University of Maryland paleontologist Tom Holtz, who gave a specific shout-out to NOVA Geoblog, encouraging the ~30 attendees to check it out. (If you're arriving as a consequnce of that endorsement, welcome!) Four of my Honors students joined me for the talk. Just getting to go behind the scenes at the Smithsonian is a treat in itself. From the Easter Island moai in the Constitution Avenue lobby of the museum, we were escorted through labyrinthine passageways to the Cooper Room. Our route brought us past immense fossil collections, cossetted away in row after row of cabinets. It was enticing, and made me resolve to arrange a special tour there sometime for the Honors students.

The point of the talk was Stanford's immense collection of fossil dinosaur tracks (and at least one apparent mammal track which is quite large: raccoon-sized at least, with apparent dinosaur skin impressions right next to it). It used to be thought that Maryland only had Triassic/Jurassic fossil tracks, from the Newark Supergroup rift valleys that opened up during the breakup of Pangea / opening of the Atlantic Ocean. Stanford has made a real scientific breakthrough by demonstrating that there are early Cretaceous-aged tracks in the area too.

None of his Cretaceous-aged tracks are collected in situ. Instead, he finds them all as "float" (weathered-out loose blocks) in streams draining exposures of (what I infer to be) the Patuxent Formation. (He didn't specifically mention source formations that I heard during the talk.)

He's found a ton of stuff! Actually,if I'm being literal, he's found tonS of stuff! And he stores it all in his living room! He recently had the foundations of his house reinforced because he has so much STUFF. Hundreds of tracks, and other fossils, too. Whoa! This guy does not play by the same rules as most folks.

There were a lot of coprolites mentioned, including:

• a 98-pound coprolite (!)
• a coprolite with a dinosaur footprint in it
• a dinosaur footprint with a coprolite in it

He also shared what he claimed were skin textures preserved in tracks. Some were self-evident, and I readily accepted them as valid. However, others weren't visible to the naked eye, and he only "demonstrated" them with Photoshopped images wherein the contrast dial was turned up to 11 -- I think this "technique" generated patterns that resembled skin impressions, but when I looked at the fossil itself, they were nowhere to be seen. I am dubious about this particular claim.

The talk gave me lots to think about, but not so much about dinosaur lifestyles or anatomy so much as the role of amateurs in science. Here's a guy with boundless enthusiasm, and he's finding stuff that the books literally said didn't exist. His efforts have resulting in expanding Maryland's Mesozoic paleontological record into the Cretaceous, and he's found all sorts of stuff that's super-duper interesting, like that mammal track.

Stanford was profiled last year in Geotimes magazine, before it switched its name to EARTH. Discovery News also ran a story about his findings. Interestingly, when Googling his name for this blog post, I also came across some other wacky stuff he's involved in, including UFO's. This definitely jibes with the lack of scientific rigor that I perceived in his presentation. (Quote from the interviewer: "In the 1970s, Stanford was the moving force behind the Association for the Understanding of Man (AUM) and Project Starlight. The former an attempt to decipher the UFO enigma by psychic means, the latter using advanced scientific instruments.")

So, having learned this, what do I make of his paleontological data? The best I can come up with is to trust my own eyes and view his claims open-mindedly but with the traditional scientific filter of skepticism. I accept the coprolite data; I found it self-evidently convincing. The skin-texture data? Not so much. The UFO stuff? Don't get me started...

Labels: coastal plain, cretaceous, culpeper basin, fossils, maryland, meetings, mesozoic, museums, psw, science and society, smithsonian

PALEONTOLOGICAL SOCIETY OF WASHINGTON

Confessions of a Dinosaur Hunter
by Richard Thompson
American Institute of Physics / AAAS Congressional Science Fellow

Wednesday, May 20, 2009 7:00 p.m., in the Cooper Room, National Museum of Natural History 10th St. & Constitution Ave.

Meet in the Constitution Avenue lobby at 5p.m. if you wish to join us for dinner, at the "Elephant and Castle," NW corner of 12th & Penna. Ave., NW

Non-Smithsonian visitors will be escorted to the Cooper Room at 6:30 and 6:55 p.m.

Last Meeting of the Season: See you in September!

Labels: dinosaurs, fossils, meetings, psw, smithsonian

Here's some cool field trips being offered by the Virginia Museum of Natural History. Not particularly cheap, though.

Labels: field trips, fossils, museums, virginia

I'm swamped -- absolutely sodden with responsibilities, of a dozen flavors. Stressed, harried, scatterbrained, and to top it all off, no time for proper blogging. But that doesn't stop me from getting excited about a new opportunity to do something cool... Even though I don't need any more credits for my MSSE degree this summer, I just found out about "Bahama Montana," an expedition into past carbonate environments of the Big Sky state, and their fossil inhabitants. Can't wait!

Eventually I'll use this credit... right?

Labels: fossils, limestone, montana, msse

When I visited the exposures along newly-minted New Route 55 in West Virginia in March, I was so impressed, I decided to bring my structural geology students there on our trip. Now, after two stops in the Blue Ridge and a late afternoon anticlinorama, we woke, broke camp, and ate some great eggs and sausage (mine were swimming in coffee due to an accident with the French Press, but hey -- it all goes the same place, right Ben?) and set off to the west.

Hanging Rock Anticline roadcut:


Hanging Rock Anticline as viewed from the valley of the Lost River, where Old Route 55 wends and winds:


Ben, Dave, and Joe on the berm (note the thrust fault above their heads):


Plenty of primary structures to be seen here, too, like these trace fossils:


A hand-sample of trace-fossils (Arthrophycus, I think):


...or this beauty:


Small reverse fault with an offset of ~1 meter:


Here's a fossil (??) that I don't understand and cannot identify. I saw four of these out there. Can anyone (Tom, ReBecca?) help me identify this sucker and understand how it formed?










We moved on down the road a bit, to this lovely monocline (Jim & Jay for scale):


John, Karine, & Ryan take a closer look at primary and secondary structures in these strata:


Lovely flute casts:


Plumose structure #1:


Plumose structure #2:


Paleo-river channels incised into these strata (at the time of their deposition):


Reduction "halo" around a carbonaceous plant fragment fossil:


Ripple marks:


More plant fossils (these were the largest I saw):


Lots of carbon films of shredded up plant chunks:


Ball & pillow / flame structures:


Ditto, and note the graded bedding in the upper sandstone layer, too:


Great trip, everyone! Thanks!

Labels: field trips, fossils, primary structures, sediment, structure, teaching, valley and ridge, west virginia

Now that we've visited a couple of stops in the Blue Ridge province, it was was time for my Structural Geology class to head out to the Valley & Ridge province.

We made a brief stop to be introduced to the Massanutten Sandstone (Silurian quartz sandstone to quartzite) at Blue Hole, where we noticed this fault zone:


...But the main show was up in Veach Gap, where there's a zillion parasitic folds on the larger Massanutten Synclinorium. This was our third Field Study Area. The anticlines are beautifully expressed in human-sized outcrops, while the intervening synclines are lost in the subsurface:














In spite of this profound deformation, there are still some primary structures to be seen, like these Arthrophycus (?) trace fossils...


...and these external molds of articulate brachiopods:


As you might be able to deduce from the angle of light in these photographs, we hit this site late in the day, and then went back to camp at a site Dave knew of, by a lovely creek. Jim and Joe cooked us an amazing dinner of pasta and meatballs, and we hung out by the campfire a bit before bed. Sleep, and then up and at 'em the next morning to move on to our final Field Study Area... (more on that tomorrow)

Labels: fossils, primary structures, sediment, silurian, structure, valley and ridge

PALEONTOLOGICAL SOCIETY OF WASHINGTON

Maryland's Lower Cretaceous Vertebrate Tracks and Trackways
by Ray Stanford, Maryland Track Project

Wednesday, April 15, 2009
7:00 p.m., in the Cooper Room, National Museum of Natural History
10th St. & Constitution Ave. Meet in the Constitution Avenue lobby at 5:00 p.m. if you wish to join us for dinner, at the Elephant and Castle, NW corner of 12th & Penna. Ave., NW

Non-Smithsonian visitors will be escorted
to the Cooper Room at 6:30 and 6:55 p.m.
Remaining Date for 2008-2009 Season: May 20

Labels: cretaceous, fossils, maryland, psw, smithsonian

NOVA Assistant Professor of Geology (Loudoun Campus) Will Straight will have his paper, "Bone Lesions in Hadrosaurs: Guided Computed Tomography for Paleohistologic and Stable-Isotopic Analysis," published as the featured article in the June 2009 issue of the Journal of Vertebrate Paleontology.

Way to go, Will!

Labels: dinosaurs, fossils, isotopes, nova

I've gotten hooked on watching these TED talks. You should too.

Here's Peter Ward talking about mass extinctions. I like this because I saw Ward give a similar talk at NSF once, and meant to blog about it, but got distracted by a thousand other things, and now here it is, a year later, and I can finally showcase this talented scientist discussing his specialty:

It gets a little fringey towards the end with talk about battle wounds and preserving people, but I like scientists like Ward who think outside the box and connect up different perpectives and different fields of inquiry. Enjoy!

Labels: evolution, fossils

Yesterday, four Honors students and I went out to West Virginia's route 55 (between Wardensville and Moorefield), to look at some sedimentary strata and associated tectonic structures. Our guide was my friend David Dantzler, an enthusiastic amateur geologist. Here's a map of the terrain we traversed:



As you can see, this is part of the Valley & Ridge province, an area of the country defined by Paleozoic rocks that were folded and thrust-faulted during the Alleghenian phase of Appalachian mountain-building. Recently, a new road has been constructed traversing these valleys and ridges. It's a bit of a boondoggle, a pet project of West Virginia senator Robert Byrd which funneled federal dollars into the Mountain State, ostensibly to make it easier for the chicken farmers of Moorefield to get their birdie bits to market on the east coast.

This image ought to give you a sense of the project's scale (big bridge), and how much use it gets (no one on the bridge):


But the U.S. taxpayer's loss is the geologist's gain... There are some pretty spectacular new exposures of Valley & Ridge rocks along the new route 55. Here's the NOVA van parked at an outcrop of Tuscarora Sandstone that is arched up into a broad anticline. Again, notice how few people are driving on route 55 here:


Ooh, look: heavy traffic!


Contact between the lower Tuscarora Sandstone (a Silurian-aged extremely pure quartz sandstone, variably fused to quartzite), and the overlying (darker-colored) formation, which is either the Rose Hill Formation or the Mackenzie Formation at this location:


We found oodles of cool trace fossils:







But it wasn't just sedimentary layers. There were also some cool tectonic structures, like this joint in the Tuscarora, showing a beautifully developed hackle fringe:



Here's some "pencil cleavage" where fine-grained shale develops cleavage that intersects the planes of fissility, causing it to fracture in long slivers:



I slammed on the brakes for this one: an awesome anticline...


I forced David and the students to act out the orientation of the bedding planes at this anticline:


Honors student Jason points out a small thrust fault in the outcrop above him: You can see the offset in a greenish/gray shale layer:


In case it wasn't obvious above, here's a zoomed-in shot, with the offset layer highlighted (the miracles of Photoshop!) and the fault labeled:


We all had a grand day outside, and the rain held off until our return trip, which was pretty great. Thanks to David for showing us these rocks, and thanks to my students for being smart and inquisitive and into field trips.

Labels: appalachians, devonian, field trips, fossils, mountains, nova, politics, primary structures, sediment, silurian, structure, teaching, valley and ridge, west virginia

Ladies and gentlemen, spring has arrived in the Washington, DC region. It is sublime. I'm very grateful that it's my spring break this week because even though I still have a ton of work to do, I've had the opportunity to get outside every day and enjoy a bit of the weather.

This weekend, I got up early both days and headed out the the Billy Goat Trail, a rugged hiking trail along the Potomac River's gorge about 12 miles upstream from DC. I departed from the trail itself both days, which was great because it brought me to places I hadn't seen before. I found a lot of cool new structures and rocks! Over the next few days or weeks, I'll be sharing some of those images with you, but for today, I figured I'd show you some 'soft' imagery, just to celebrate the fun of being outside on a hike on a lovely day. ...and wearing short sleeves, no less!

Here's a shot of typical scenery along the Billy Goat Trail. This is looking upstream:



One of my side-trips off the trail... because the water level was pretty low, I was able to get to some islands that are often inaccessible. This is the channel between the Rocky Islands (downstream of Great Falls, upstream of Mather Gorge):



This land is all part of the C&O Canal National Historical Park. Here's a spot where rains from Tropical Storm Hanna breached the wall of the C&O Canal, allowing its water to drain downward into the Potomac. Because the canal's towpath was located there, the Park Service has constructed a temporary path which detours around the breach:



I saw some good birds on my hikes there. Red-tailed hawks, double-crested cormorants, Canada geese, mallards, belted kingfishers, pileated woodpeckers, red-bellied woodpeckers, tufted titmice, chickadees, robins, blue jays, and great blue herons. Also, both local species of vultures: the turkey vulture and the black vulture. This is a black vulture (note the black, not red, head):



Here's some tracks: theropod dinosaurs? ...or great blue heron? You be the judge:



Here's a cool fish skull I found:



Of course, it wasn't all scenery, birds, and fish. There were rocks, too. I took a lot of rock photos, and you'll get to see them all in due course... But for now, let me start you off with the tame stuff. Here's some cobbles I encountered along the hike...

Cobble of the Seneca Sandstone (Triassic arkose) showing a mudchip rip-up clast:



Tilting it a bit, you can see other mudchips too:



Cobble of cement containing Seneca chunks:



Cobbles of quartzite of the Antietam Formation showing Skolithos 'worm' tube trace fossils:



I love these Skolithos tubes. It's hard not to love them, and they're everywhere around here. Like the Seneca cobbles, they come from source areas to the west (Culpeper Basin & Blue Ridge, respectively), and were transported to the Maryland Piedmont by the ancestral Potomac River.



My favorite Skolithos-bearing quartzite cobble:



...And the same cobble, end-on:



More to come, tomorrow...

Labels: birdies, blue ridge, culpeper basin, fish, fossils, maryland, national parks, piedmont, sediment

Brilliant! Especially in light of the new fossil evidence about the origins of whales released earlier this year.

From last week's issue of the New Yorker, which I've got time to read today because it's a snow day here in DC!

Labels: art, evolution, fish, fossils, humor, mammals

Today, I would like to share with you some spectacular images that I took using a new toy, a Nikon binocular dissecting microscope with digital camera mount. These photos show a limestone in which you can find a large number of the single-celled foraminifera called "fusilinids." These benthic forams are about the size and shape of grains of rice, and here you will be looking at them in cross-section, seeing the spiral shape with numerous internal chambers that helps support their cytoplasmic bulk. Remember that these are macroscopic, not microscopic: each fusilinid is a single cell the size of a rice grain!




Now, you might be wondering why I'm so keen on showing off fossils. After all, this isn't a paleo blog... But there's more than just fossilization going on here. These fusilinids have also been squeezed. The weight of overlying sedimentary strata has compressed this rock perpendicular to the bedding plane, (top to bottom, in all these photos) and some of the fusilinids got crammed against their neighbors. Now, fusilinids make their skeletal material from the mineral calcite, and calcite can go into solution when the pressure is high enough. In places, you can see where one fusilinid has penetrated into its neighbor, dissolving the neighbor away as it intrudes. The following two images are close ups of the upper image. Photo #2 is from the lower left of the first image; Photo #3 is from the upper right of the first image:






In both, you can see where the edge of one of these internally-spiraled, ellipsoid-shaped fusilinids has dissolved its way into a neighboring fusilinid, disrupting the neighbor's internal architecture and symmetry. Insoluble minerals like dark-colored clays build up along this dissolution horizon. Here's one more photo for good measure:




Pretty cool, eh? The fossils serve as strain markers, hinting to us about how much of the rock's calcitic volume has been lost.


I would like to thank the Nikon representative who demonstrated the camera for me, Stanley M., for taking the time to show how the device works, and for allowing me to make some images before I had officially bought the thing.

Labels: fossils, limestone, structure

PALEONTOLOGICAL SOCIETY OF WASHINGTON

Institutional Memories: The Paleo Art of National Geographic and the Smithsonian Institution
by Angela Botzer (National Geographic) and Mary Parrish (Scientific Illustrator, Dept. of Paleobiology, National Museum of Natural History, Smithsonian Institution)

Paleo art has been an important part of the dissemination of the science of paleontology for two important Washington, DC institutions and their audiences for more than 150 years. The presenters will detail fascinating histories of paleo art via the material housed in the collections of their respective organizations.

Wednesday, Feb. 18, 2009
7:00 p.m., in the Cooper Room, National Museum of Natural History
10th St. & Constitution Ave. Meet in the Constitution Avenue lobby at 5:00 p.m. if you wish to join some fun paleontologists for dinner, at the "Elephant and Castle," NW corner of 12th & Penna. Ave., NW. Non-Smithsonian visitors will be escorted to the Cooper Room at 6:30 and 6:55 p.m.

Remaining Dates for 2008-2009 Season: March 18, April 15, May 13

Labels: art, dc, fossils, meetings, psw, smithsonian

A graduate of my summer Snowball Earth course just forwarded me a link to a news item about a recent discovery which finds biomarkers exclusive to the sponges during Marinoan-glaciation-aged sediments on the Arabian Peninsula. The strata are "at least 635 million years old."

This is significant because the usual line about Snowball Earth is that multicellular animals show up after the glaciations end, not during. So what's going on here? Looks like we didn't understand the thing as well as we thought. For many people, the co-incidence (in the most literal sense) in timing between the end of the glaciations and the first multicellular animal fossils was one of the most intriguing things about the Snowball hypothesis -- we all want to know where we came from, after all -- and this may take some of the wind out of those sails. As humans, we like a good story, and this may be one reason the idea of a Snowball Earth is such a popular notion: it's a dramatic story about where we came from, and one that stretches our conception of the limits of change on our planet. But now that story exhibits a flaw upon closer scrutiny, and it makes it less satisfying. The consolation prize is that event though the story isn't as neat, it's closer to the truth. That's the way science works -- especially earth science, which isn't often as tidy as a fairy tale.

Hat tip to Christina T. for passing this on!

UPDATES: (1) Chuck read the paper and wrote it up at his blog. (2) WIRED magazine is also reporting on this, calling the discovery the world's "oldest animal fossils." I'm not sure I agree with that phrasing -- but that probably stems from my lack of familiarity with the reliability of biochemical signatures over traditional body or trace fossils.

Labels: chemistry, fossils, geology, porifera, proterozoic, snowball earth

The International Year of Planet Earth may have declared a list of "the Earth's ten most spectacular places." At least that's what they're saying at the Discovery Channel's new Discovery Earth site, where they have a rundown of all ten (with photos). (No mention of it at the IYPE site, though: It may be that the Discovery Channel is just highlighting ten of the many, many U.N. World Heritage sites... their language is unclear as to who decided on these particular ten.)

Regardless, the photos will whet your appetite. With my visits in bold, they are:

• The Giant's Causeway, Northern Ireland (posts on NOVA Geoblog)
• Wadi Al-Hitan (Valley of the Whales), Egypt (Eric's been posting on this recently)
• Lake Baikal, Siberia (deep, big)
• Komodo National Park, Indonesia (big monitor lizards; my friend Kenny has been)
• Grand Canyon, Arizona, USA (posts on NOVA Geoblog)
• Ilulissat Icefjord, Denmark (glacial beauty)
• Wulingyuan, China (quartzite pillars and indigenous fauna)
• Surtsey, Iceland (46 years old this year)
• Central Amazon, Brazil
• Great Barrier Reef, Australia

Labels: antrim coast, asia, australia, china, fossils, giants causeway, glaciation, grand canyon, ice, reefs, south america, travel, water resources

When critters interact with their environment, sometimes they leave behind traces of that interaction. If we're lucky, these traces fossilize and can be preserved through time to tell us interesting things about the past. This past summer, when I rafted down the Grand Canyon with my father and two brothers, I saw some cool trace fossils. In chronostratigraphic order (earliest first), here they are:

The Bright Angel Shale can be found atop the Tapeats Sandstone, and below the Muav Limestone along the river in much of the canyon. The Bright Angel is middle Cambrian in age. For my money, it's one of the most spectacular sedimentary layers there, because it's so varied. The colors of the individual strata range from purple to green to brown to tan, and they are in many places chock full of horizontally-oriented feeding traces. Here's some of those wormy shapes along the trail to a waterfall we hiked to... (sorry, don't remember the name or exact location... I think it was day 4 or so of the overall trip... Hmmm, I guess I should have blogged this in early July when I photographed it...)





Nearby, we saw a spectacular trilobite crawling trace (Cruziana?):



Earlier in the trip (day 1, at lunchtime), and higher in the stratigraphic stack (the Permian Coconino Sandstone, which is a sand dune deposit), we saw these reptile (synapsid?) footprints:



This is a trackway left by an ancient reptile as it was walking up and down the dunes, preserved on the slip-face (which defines the feature we recognize from a side-view as "cross bedding"), and now, 260 million years later, I'm viewing those same tracks from underneath, as the older slip-faces of the dune have peeled off, and only the overlying (younger) ones are preserved in this particular alcove. Pretty spectacular stuff. And it offers some nice lunchtime shade, too... Can't complain about that. Here's another shot, with a sense of scale in it:



You can see the individual toes! Wild!

Labels: arizona, cambrian, fossils, grand canyon, permian, primary structures, travel

Recently, Andrew Alden compiled a list of state minerals and state rocks. A quirky piece in today's Washington Post explores what Maryland is urging its citizens to do with their state fish: eat them. The story also, somewhat randomly, includes a limerick composed by Virginia's former governor and current senator, Mark Warner:

We have a state dog and a fish and a bird.
And of the fossil I'm sure you have heard.
So why not a bat?
What's wrong with that?
The state beverage is no more absurd.

For some reason, I hear this limerick in my head in Carl Kasell's voice...

Labels: birdies, critters, fish, fossils, mammals, maryland, politics, virginia

Students! What will you do next summer? I've done some work with the good folks at the Center for Urban Ecology in DC, which works with the national parks in the National Captial Region. I was notified today that they're in search of a GeoCorps participant to complete a paleontological inventory of the area's parks.

Could be fun! The relevant info is below, or you can see it all on the GeoCorps site.

Public Land Name:	Center for Urban Ecology, National Capital Region, National Park Service
Position Title:	Geosciences Research Assistant / Paleontologist
Position ID Number:	208
Location:	Washington, DC
Position Description:	The work of the GeoCorps participant will build upon a paleontological inventory of the National Capital Region’s parks conducted in 2004 which revealed remarkable assemblages containing vertebrate, invertebrate, and plant fossils distributed in four distinct physiographic regions. The participant will conduct paleontological resource site condition assessments, complete documentation, and help establish a monitoring program for fossil sites in the Chesapeake and Ohio Canal National Historic Park (MD, DC), Manassas National Battlefield (VA), and National Capital Parks-East (MD, DC). The position will include both office and field work. Most of the time will be spent conducting field paleontological surveys to fully document localities and to undertake site condition assessments. Site visits will be conducted by vehicle and on foot. While working in the field, the participant will ensure that NPS regulations and safety procedures are being followed. Office duties will include reviewing literature, preparing documentation for entering into NPS databases, building a photographic library, and drafting recommendations for site monitoring. Participants may have an option to use a portion of their time for self-directed research after approval from regional and park staff. Prior to starting this position a government security background clearance will be required. This position is offered through the Geological Society of America's GeoCorps America Program in partnership with the National Park Service's Geoscientists-in-the-Parks Program.
Qualifications:	Undergraduate/graduate coursework and/or field experience in paleontology, with preference given to knowledge of the Mid-Atlantic region. Applicant must have completed at least three years of college-level coursework. Graduates students, faculty, and active and retired professionals are also welcome to apply. Experience in the field, discovery and evaluation of paleontological resources, particularly trace fossils, is important. The applicant should be able to work well independently, both in the office and in the field, have basic map reading and GPS skills, and must be comfortable both working outdoors and negotiating a busy city. Basic computer skills are required. Applicant must have a valid driver’s license and a good driving record.
Position Dates:	12 weeks with flexible starting dates in April-May
Payment:	$2,750.00
Housing Available:	Housing will be provided at no cost to the participant most likely at Brookmont House (George Washington Memorial Parkway) in Washington, D.C. This is a 3-bedroom house shared with up to two other people. There is public transportation available but grocery shopping and other services are limited in this area, so having a personal vehicle is highly recommended.
Physical/Natural Environment:	Parks of the National Capital Region (NCR) encompass numerous sites ranging in size from less than one to over six thousand hectares that provide a diversity of experiences and landscapes. The 15 national parks of the National Capital Region lie within four physiographic provinces: Coastal Plain, Piedmont, Blue Ridge, and Ridge and Valley, and contain significant geological resources. These parks include areas with national icons (the National Mall), national battlefields (Antietam, Manassas, Monocacy, Harpers Ferry), and natural forests (Catoctin Mountain Park and Prince William Forest Park), all amidst the rapidly growing metropolitan Washington, D.C. This unique setting provides great opportunities to gain insights into issues related to urban ecology and integrated management of cultural and natural resources.
Work Environment:	The Center for Urban Ecology (CUE) houses the Natural Resources and Science Division, which is an interdisciplinary team that provides scientific guidance, technical assistance, and education for the preservation and enhancement of park resources in the National Capital Region, National Park Service. Working with resource managers, researchers, and the public, CUE strives to discover and incorporate new ways to understand, preserve, and enhance natural communities within and around the national parks in the metropolitan Washington, D.C. area. CUE is located in the Georgetown area of Washington, DC, in a Rock Creek Park facility. Laboratories at CUE are fully equipped to support research in botany, plant health (pathology), entomology, hydrology, aquatic biology, soils, and wildlife biology.
# of current Applicants:	0

If you have questions about the application and selection process, please contact Anny Jones. If you have questions about any aspect of the position - description, qualifications, housing, dates - please contact the primary or secondary contact below:
PRIMARY CONTACT INFORMATION Contact Name: Giselle Mora-Bourgeois Title: Science Education Coordinator Address: 4598 MacArthur Blvd, NW City/State/Zip: Washington, DC 20007 Phone: 202-342-1443 Ext 220 Email: Giselle_Mora-Bourgeois@nps.gov Website: http://www.nps.gov/cue/	SECONDARY CONTACT INFORMATION Contact Name: Vincent L. Santucci Title: Chief Ranger Address: George Washington Memorial Parkway Turkey Run Park City/State/Zip: McLean, VA 22101 Phone: (703) 289-2531 Email: vincent_santucci@nps.gov Website: http://www.nps.gov/gwmp/

Labels: dc, fossils, jobs, national parks

As I mentioned yesterday, the Virginia Department of Geology and Mineral Resources has an excellent rock garden outside their office in Charlottesville, displaying a diverse suite of large rock samples from across the state's five physiographic provinces.

Here's Rick Diecchio (George Mason University) providing a sense of scale for the rock garden:


Here's a few of the samples that caught my eye, with my shoe providing a sense of scale (size 12, specifically) in each image...

Aquia Formation sandstone with Turitella fossils (Paleocene); King George County:


Balls Bluff Siltstone with mudcracks (Triassic); Culpeper County:


Conococheague Formation collapse breccia (Cambrian); Augusta County:


Cranberry Gneiss (?) showing well-developed lineation (Mesoproterozoic); Grayson County:


Kyanite quartzite (probably Ordovician metamorphic age); Prince Edward County:


Fossil Sigillaria tree trunk from the Wise Formation (Pennsylvanian); Wise County:


Unakite, the state rock of Virginia according to some (Mesoproterozoic); Rockbridge County:


Here's a link to the PDF (1.82 MB) with all the details about all the rocks in the garden, an impressive achievement just like the symposium.

Labels: conferences, fossils, igneous, meetings, metamorphism, primary structures, sediment, virginia

Here's a fossil that I have hanging around my house; it's an ammonite from the Bearpaw Shale (late Cretaceous) of eastern Montana. I collected it just south of Glendive, Montana, this summer on the "Dinosaur Paleontology of the Hell Creek Formation" class I took through the MSSE program at Montana State University.

Overall, this little fellow has a maximum diameter about the same size as a quarter:


On the back side, where the nacre has been broken off, you can see the suture patterns:


Clearly, these are ammonitic sutures (as opposed to ceratitic or goniatitic), but I haven't identified it to genus level. Any paleontologists out there able to help me out with an ID?

Labels: cretaceous, fossils, montana, msse

Hat tip to Michelle A. for the link!

Labels: canada, devonian, fossils, humor, music

Chris Nedin has a funny and insightful/educational post up at his Ediacaran blog: entitled "CSI Cambrian," he explores the death of a trilobite through murder-mystery dialogue.

You should check it out, before you do anything else.

Labels: blogs, fossils, humor

I've already posted some images from the VCCS Science Peer Conference a week and a half ago. Outside the offices of the Wintergreen Nature Foundation, they've arranged a series of large charismatic rock samples from the region. Some of them are from the Blue Ridge (where Wintergreen is located) and some are from adjacent physiographic provinces. These samples are from the Valley and Ridge province, showing some cool features sometimes found in sedimentary rocks.

First, some articulate brachiopod fossils in quartz sandstone (internal/external molds). This wasn't labelled as to its source formation, but it looks a lot like the Oriskany Sandstone, a major ridge-former in the Valley and Ridge. Quarter for scale.


Second, a breccia in limestone. (FYI, Andrew's Oakland Geology blog has another nice image of breccia today.) Perhaps a collapse breccia? Again, the sample wasn't labelled, so I have no idea which formation it was derived from. The white in-filling is calcite. Quarter for scale.

Labels: conferences, fossils, sediment, valley and ridge

Labels: ediacaran, fossils, psw

My favorites from a recent raft of geoblogosphere posts:

• Field work on sedimentary rocks in the Dead Sea region of Jordan (from Nologic)
• Anomalocaris fossils (from Ediacaran)
• Charming but obsolete mining terms (from Hypocentre)
• Other cool stuff in a similar conglomeration from BrianR (at Clastic Detritus)

Labels: blogs, field trips, fossils, geology, mining

Yesterday, I pulled up the Venetian blinds in my office window at NOVA, and this is what I saw:


Naturally, I had to take a photograph. It's puuurty.

While I had the camera out, I figured I'd shoot a few photos of the rest of my office, since it's full of all sorts of interesting clutter. Rather than explaining what all the doodads are in these photos, I figured it would be more fun to just post them and see if you can identify them all:















Have fun!

Labels: fossils, igneous, maps, metamorphism, minerals, nova, plants, sediment

Yesterday was the Geological Society of Washington's fall field trip. A group of about twenty of us went down to George Washington Birthplace National Monument, a stretch of land in the Virginia Coastal Plain, about an hour east of Fredericksburg. The trip was lead by Wayne Newell of the USGS in Reston and Rijk Morawe of the National Park Service.

Here's a map of the Monument, adjacent to a small bay formed as the valley of Popes Creek flooded with post-glacial sea-level rise (essentially the story of the entire Chesapeake Bay in miniature):


Wayne and Rijk are studying the coastal processes here in an attempt to use the Popes Creek as an analogue for Chesapeake Bay processes in general. One of the reasons they really like it is because unlike other small bays in the area, it has a spit (almost a baymouth bar) protecting it from the ravages of the tidewater Potomac (which it flows into). Here's the spit heading southeast across the mouth of Popes Creek Bay:


This rotted old wooden seawall was erected along the coast in the 1960s. This is on the Potomac, just upstream from the Popes Creek Bay. Effectively, this seawall serves as a "before" line, a marker which conveys the shoreline's former position. You can see how much erosion has taken place since then:


I'm less interested in these coastal dynamics, though, than I am in the bedrock geology. There were some bluffs along the river which exposed the Miocene Calvert Formation (clay-rich lower unit) topped by a foot-thick diamictite unit, and then well-rounded river gravels on top of that:


Here's Merily (sp?) from AGI checking out the sequence of strata:


My favorite part of the trip was looking at the variety of cobbles on the beach. These cobbles are derived from all of the mid-Atlantic's physiographic provinces within the Potomac River's watershed (Valley & Ridge, Blue Ridge, Culpeper Basin, Piedmont, Coastal Plain). All those physiographic provinces have been weathered to produce the sediment that the Coastal Plain is made of. In spite of their diminutive size, they give insights into the geologic history of Virginia over the past billion years. So if you're familiar with Virginia geology, you will see some familiar rocks here.

For instance, there were a lot of these Skolithos-bearing quartzite cobbles. These are pieces of the Antietam Formation, a meta-quartz-sandstone that crops out in the Blue Ridge province, many many miles upstream:


Skolithos is the name given to vertically-oriented cylindrical burrow trace fossils, which start showing up in the Cambrian period of geologic time, indicating the evolution of vascularized bodies among animals. They are usually interpreted as worm burrows. This cobble shows several different diameters of Skolithos tubes:


Here's a cobble of another distinctive Blue Ridge rock. This amygdular meta-basalt is a piece of the Catoctin Formation, a sequence of (mainly) mafic lava flows that erupted as the supercontinent Rodinia was breaking up in the Neoproterozoic era of geologic time. The white spots you see are amygdules: vesicles that have been filled in by mineral deposits. When lava erupts, it degasses. If the lava cools into extrusive igneous rock before the bubbles have a chance to pop, little round holes are preserved in the rock, like Swiss cheese. We call these "vesicles." When vesicles get filled in with deposits of minerals (from groundwater passing through the rock), they are called "amygdules," from the Latin for "almond," which I guess they resemble in an ellipsoidal sort of way:

(I showcased a very similar cobble here in March of this year.) Like the Antietam Formation cobbles, this Catoctin Formation cobble originated in the Blue Ridge province, and has tumbled dozens of miles downstream to end up out here on the Coastal Plain.

Here's one from even further away! This is a cobble of flint from one of the limestone units out in the Shenandoah Valley, the easternmost valley of the Valley & Ridge province. (I've previously posted on those rocks, too.) While the limestone which originally hosted this flint nodule has weathered away, the flint is microcrystalline silica: very hard, very chemically stable. It's a common cobble to find surviving out here in the Coastal Plain:

We also found some rocks that are distinctive occupants of the Culpeper Basin, a Triassic-Jurassic rift valley upstream. Here's a chunk of the Manassas Sandstone Formation, another rock that has been previously mentioned on this blog:


The rock I spend most of my time thinking about is the metagraywacke of the Mather Gorge Formation. (For one mention on NOVA Geoblog, click here.) Here's a piece of it that looks identical to the rocks you'll see near Chain Bridge, DC, or along the Billy Goat Trail (Potomac, Maryland):

This rock was metamorphosed ~460 million years ago, in the late Ordovician, although the original sediments are older than that: perhaps Cambrian or late Neoproterozoic in depositional age. This sample even had a little bit of hydrothermal quartz stuck to it, a common feature of Piedmont metamorphics...

Having covered clasts derived from the Valley and Ridge province, the Blue Ridge province, the Culpeper Basin sub-province, and the Piedmont province, there's nothing left in the Potomac River watershed except for the Coastal Plain itself. And sure enough, we saw Coastal Plain clasts too. Here's a chunk of the Calvert Formation that GSW Field Trip Chair Bill Burton found: He cracked it open and found a shark tooth fossil inside:

This is the first time I've ever seen a tooth preserved as a carbon film. Except it wasn't really just a film, it was more a three-dimensional external mold with a carbon film, and little nuggets of carbonaceous material rattling around inside. Shark's teeth are pretty common in Miocene deposits on the Coastal Plain, including C. megalodon teeth, but this style of preservation was pretty novel for me. If you're into fossil collecting, don't go to George Washington Birthplace National Monument, because collecting isn't allowed there. However, nearby Westmoreland State Park offers legal fossil collecting opportunities. It's about ten minutes further south.

I'd like to thank the field trip leaders and Bill Burton for organizing the trip. I enjoyed the excursion!

Labels: coastal plain, field trips, flint, fossils, gsw, rivers, sediment, virginia

Today's science seminar went well. There was a reasonably full house (maybe 150 or 200 people?) and most of them looked reasonably awake all through it. Afterwards, I had some new folks express interest in my Rockies field course for next summer. Additionally, a bunch of the audience stuck around to look at some rock and fossil specimens I had brought along. When I got back to my office, there was a nice note in my in-box from the provost, who had attended and complimented the talk. And then I got a free lunch with three of my colleagues! Chinese food... makes me sleepy, but dang, it was good.

Here's the slideshow I gave, via SlideShare.net (The embedded version below doesn't seem to be working for me, so here's a direct link to the PPT on SlideShare):

Labels: food, fossils, geology, grand canyon, meetings, travel

This spring, I mentioned reading Kirk Johnson and Ray Troll's book Cruisin' the Fossil Freeway, and then stopping in and visiting with Kirk in Denver one evening on my summer road trip.

Now, my friend Michelle (who both loaned me the book and introduced me to Kirk) has forwarded me an announcement: Ray and Kirk are coming east!

Labels: dinosaurs, fossils, humor, meetings

If you didn't already catch it elsewhere, there's a new fossil from the Chengjiang Fauna that suggests a bunch of arthropods following one another in a line. Matt at the HMNH reports on it here.

Labels: arthropods, blogs, cambrian, fossils

This weekend, I walked down to the Smithsonian Institution's National Museum of Natural History to check out their new Sant Ocean Hall (previous mentions on this blog).

The new exhibit hall has been under construction for a long time, and opened to the public the previous weekend. I've got a few photos here to share some of what I saw, but the museum also maintains their own Flickr page, which has additional (and better) photographs.

It's pretty cool. There are suspended specimens of both giant squid and also this coelacanth (with "pup" at upper right):


The exhibit has a lot of cool stuff having to deal with the geological aspects of oceanography, too, like this interactive exhibit about drill cores and how geologists interpret sediment. It would make an ideal visit for Historical Geology students:


The thing that caught my eye at first was a series of skeletons showing the evolution of whales over time, and in particular the shrinkage and eventual absence of their hind limbs and hips. I failed to note the name of the first one (falsely thinking I could look it up online!), but the more distant two specimens are Dorudon and Basilosaurus:


And they've got a nice C. megalodon jaw reconstruction holding lots of authentic teeth:


There are lots of smaller fossils, too. I was really impressed by the substantial portion of the hall which was given over to ancient oceans, as preserved in the sedimentary record. Here's a case showing some stunning fossils, including a MASSIVE asaphid trilobite and the best receptaculid ("sunflower coral") that I've ever seen:


A lot of trilobites are on display, most donated by Bob Hazen, of the Carnegie Institution and George Mason University. Here's a lovely Olenellus from Pennsylvania:


Also, you'll find Dunkleosteus, mosasaurs, and this Placinticeras ammonite with mosasaur bite marks running across it.


Here's a rudist clam, one of a half-dozen diverse and chunky specimens on display:


Lastly, I'll show a photo that's part of their display on the Burgess Shale. They include some imagery from Walcott's journal documenting actual fossil specimens that are displayed right along with it. Pretty cool -- a sort of window onto historical paleontological field work.


I also wanted to mention a really neat display called "Science on a Sphere," where a suspended sphere about six feet across gets imagery projected on it from the inside, accompanying narration that explains phenomena like plate tectonics, El Nino, the thermohaline "conveyor belt," and so forth. This YouTube video (not mine) gives a small taste of the Sphere as it explains surface currents using rubber duckies:



All told, it's a great exhibit, and you should check it out next time you're in DC.

Labels: fish, fossils, museums, oceans, smithsonian

Labels: fossils, mammals, meetings, oceans, psw, smithsonian

Over the past couple of weeks, I've watched a number of videos that readers of this blog may be interested in. Yesterday, I blogged about A Private Universe and Minds of Our Own. Let me mention a few others today.

The Life of Mammals is a BBC production by the great David Attenborough, who also made Life of Birds, Life in the Freezer, Trials of Life, etc. etc. etc. (Attenborough has been making nature documentaries for the BBC since the late Miocene.) If you're into geology as part of a larger natural system, or if you happen to be a mammal yourself, this is a series well worth watching. Attenborough has a signature style involving showing up in different corners of the Earth, and carrying on a continuous narration the whole time. One moment he's in Tasmania, the next in Brazil, but his thought process is uninterrupted. The discussion is of the highest quality, without being too technical. He's got a real gift for this business. Five stars.

I also watched Walking with Prehistoric Beasts, from the Discovery Channel. It's about past creatures; Cenozoic mammals and birds. Because the animals it describes are extinct, it can't have footage of the narrator (Kenneth Branagh) strolling amongst the entelodonts or Andrewsarchus. Instead, they've used puppets and lots of computer generated animation to depict their subject. They're pretty clever about this, using "film" techniques that give it the flavor or an actual nature documentary: They mimic night-vision footage, for instance, as well as "handheld" camera shakiness, herds fleeing an overhead "helicopter" perspective, and the subjects nosing up to the "camera lens." While the animals they describe are quite interesting, I found the production to be a bit on the bombastic side, with pounding music intended to raise the viewers' adrenaline levels during a hunt scene, and so on. All told, the content wasn't as good as Life of Mammals, but I appreciated the way they handled the production, so I'd give it 3.5 stars.

Labels: critters, fossils, mammals, movies, teaching, tv

News: The coprolite cartoon I mentioned last week (published this month in EARTH magazine) is now going to be part of a permanent display on scat and coprolites at the Dinosaur State Park museum in Rocky Hill, Connecticut. My favorite part about this idea is where the new exhibit is going to be... it's in the bathroom! Ha! You gotta love that... talk about a teachable moment!

Labels: art, connecticut, fossils, humor, museums

A new study in Current Biology looks at mitochondrial DNA evidence from 160 woolly mammoth fossils on both sides of the Bering Land Bridge, and finds that the beasts trooped east from Asia into North America, and then marched back again 40,000 years ago, at which point the Asian mammoths slid into decline and extinction. The interpretation by the study's authors is that the North American prodigal mammoths returned to the mother country and possibly wiped out their Asian cousins.

The original article on the Current Biology* site. *Link wasn't working quite right this morning...
Scientific American's treatment of the story.
An article in the New York Times reviewing the study.

Labels: alaska, critters, fossils, mammals, pleistocene, russia

Labels: art, fossils, humor

The Washington Post today reports on a beer that is brewed using strains of yeast extraced, Jurassic Park style, from "45 to 25 million year old" amber:

G. Oppenheim, "The Beer That Takes You Back... Millions of Years," The Washington Post, September 1, 2008, page C01.

Also, the CalPoly magazine reported on the same story this spring.

Gives new meaning to the moniker "Amber Ale"...

Labels: fossils

The coolest research website you haven't seen is on Whitney Hagadorn's page at Amherst.

With undergraduate student Martha Buck, he's taken pyritized trilobite fossils from the upper Ordovician Frankfort Shale ("Beecher's Trilobite Beds") near Rome, New York, and X-rayed them. A series of X-ray images taken at different angles have been spliced together into a movie, which gives a real sense of the three-dimensional nature of the fossil, as well as insight into the finer details of its anatomy like legs and antennae, which don't often fossilize:

This is Triarthrus eatoni. You can replay the movie by refreshing the page on your Internet browser. The full suite of images is available on this page. Check it out!

Labels: fossils, ordovician, websites

Here's a few photos from the terrific drive-through geology exhibit called Dinosaur Ridge, near Morrison, Colorado (type locality of the Morrison Formation).

On the advice of my friend Michelle, I made a special detour to check out the area on my drive out west in June. It was worth on many levels, but my favorite part of the array of neat geology was this section, where you can see three-dimensional cross sections (if that's not an oxymoron) of sauropod footprints.

The idea is that when these sediments were wet and pliable, adult Apatosaurus (or a similar brontosaur) walked on by, sinking down into the wet sand and mud. Layers of sediment beneath were compressed (as if beneath a dropstone) and then a later deposit of sand filled in the "brontosaur bulges," preserving them. Now they are weathering out of the Dakota Hogback in relief!

Labels: colorado, dinosaurs, fossils, travel

Today: a few photos of neat stuff from the Sternberg Museum of Hays, Kansas. These are from my first time through Hays this summer, in June. It's worth a stop. Some of these are from their permanant collection, and some from a travelling exhibit of fossil reconstructions called "T. Rexcetera."

Archelon, mega turtle of the Western Interior Seaway


Pterosaur -- the flying Chihuahua of its day


Plesiosaur (I like how fierce this one looks, and the contrast in colors between its teeth and its bones -- reminds me of the Joker in the Batman movies...)


Big honkin' mosasaur skull (Tylosaurus? I should have taken better notes...)


Yipes! Under the Sternberg's dome, there are reconstructed beasties...


Beautiful slab of Uintacrinus, a stalkless crinoid (more here)


I think this last one is so beautiful that I just switched my desktop background image to it (from the previous image, a geologic map of the Moon).

Labels: chalk, cretaceous, fossils, kansas

Back in Bozeman again after a great four day stint in Yellowstone National Park. I was up in the Lamar Valley ("Serengeti of North America"), checking out megafauna as part of my "Wildlife Ecology of the Greater Yellowstone Ecosystem" course. The hyper-enthusiastic course instructor, Dave Willey, took us to see this amazing ecosystem, using the wolf-elk relationship as a platform for understanding ecological connections. Dave knows a lot about wolves, and showed us plenty. We mainly observed the Slough Creek Pack, but we also saw one of the Druid Pack (the 'original' pack that was reintroduced to Yellowstone in the late 1990s). We also got to observe black bears, elk, bison, grizzly bears, coyotes, bighorn sheep, and a bunch of birds-of-prey.

One bear encounter is worth recounting here: We had hiked from the Lamar Valley out to Cache Creek, where rumor had it the Druid Pack had holed up. We spent the morning "glassing the slopes" (searching with binoculars), but didn't locate any of the wolves. No one had seen them in three days, and we were having the same luck. We began hiking back to the Lamar and our van. At one point, our group separated into two groups. I was at the tail end of the front group, and stopped to answer the call of nature before dropping down to the flat Lamar Valley floor. This short break to take a pee ended up preventing a major bear encounter, as it turned out. Why? It gave the front group time to get down ahead of me, so instead of staring at their backs, I was looking out over the valley. And there I saw two grizzlies heading through the sagebrush, on a direct line towards my colleagues! I called out to warn them (they couldn't see because they were on the same level as the bears, not elevated like I was). We all moved up onto the hill, so we could see the bears and the bears could see us. The tail end of our group caught up, and Dave shouted at them to get up to the high ground. Then we noticed another group of hikers, heading in on the trail. Through the binoculars, we could see that they were oblivious of the bears. We shouted to them too, and they moved up towards us. At that point, the lead bear huffed up and started galloping! "Oh shit," Dave said, "Who's got the bear spray?" When your wildlife ecology professor says "Oh shit," it's time to start worrying. Fortunately the bear's gallop lasted only twenty feet or so (a mock charge?) and then the pair resumed their amble through the sage. They crossed the trail a few feet from where the other group of hikers had been, and headed up a small wooded valley.

We all breathed a sigh of relief, and ventured down off the hill and onto the trail again, keeping a wary eye on the wooded valley. Safely past it, we relaxed and began hiking normally again, at which point we got a great look at a big black wolf trying to cross the Lamar River to our left! It was definitely the closest we had been to a wolf all week! The wolf got spooked by some fishermen, however, and retreated up the hillside on the other side of the road. Pretty cool stuff to see. The Yellowstone Ecosystem appears to be alive and well, even with wolves being "delisted" as threatened species in March, and then reinstated as "endangered" yesterday.

Also, while we were there, a man was attacked by a (probable) grizzly in his tent two campsites up the road. Pretty scary stuff, no longer being at the top of the food chain. These animals will eat you! For me, it was really insightful to get to experience some of that firsthand. This trip was the first time I had camped in the park (in spite of numerous visits over the years), and I really enjoyed the early morning and late evening wildlife viewing: that's the time to be out there!

Labels: critters, fossils, msse, national parks, yellowstone

Got back yesterday from six days out in eastern Montana, at Makoshika State Park. I was there on one of my four MSSE classes this summer, and I learned a lot. As many of you know, I'm trained as a structural geologist, not a sedimentologist. Though I use a lot of sedimentology (and fossils) in my Historical Geology course, there is much I have left to learn. Some of those gaps got filled in this week during "Dino Camp," though. Plus we had a lot of non-geologic fun!

The Hell Creek Formation is well exposed in Makoshika, as well as the overlying Fort Union Formation. The Hell Creek is latest Cretaceous, while the Fort Union is earliest Paleocene. The boundary formerly known as "K/T" is therefore between the two, and it records the changing of the eras: from Mesozoic to Cenozoic. I say "formerly known as K/T," since Tertiary is an archaic term that has been replaced (sort of) with Paleogene. The Paleocene is the first epoch in the Paleogene period. The sedimentologically-defined boundary between the two formations is the lowermost "significant" coal layer. We found this coal, the so-called "Z Coal," and you'd think that would be the K/Pg boundary, but it ain't that simple. True, there are dinosaurs below and no dinosaurs above, and it's also true that the Z Coal has been shown (rather shoddily, by the description we got) to have an iridium anomaly at its base. But there aren't any dinosaur fossils at all for 3 meters below the Z Coal, so the dinosaurs could have gone extinct well before the Z Coal was deposited (and before the iridium-rich clay layer was deposited). And of course, there's nothing in the deposition of a layer of coal that indicates it should be contemporaneous with a mass extinction -- it's just coal. Furthermore, the coal is lake coal, and the lake wasn't necessarily regionally extensive. It's a funny way of defining a critical geochronologic boundary: by the lowermost layer of lake coal in an area -- a criterion which could vary temporally from one place to another. Tricky business!

Anyhow, we prospected for dinosaur fossils. The course had two instructors, Jim Schmitt and Frankie Jackson. Frankie is a paleontologist, and she had a permit for collecting fossils on behalf of the Museum of the Rockies here in Bozeman. We found a lot of vertebrae, some five or six inches across. Plus, we found a bunch of leg bones, some rib fragments, and one of our team actually found the top of the frill on the back of a Triceratops skull! It was all pretty impressive.

In the evenings, we discussed scientific papers about field technique, the Hell Creek Formation, taphonomy, and the extinction of the dinosaurs. All our meals were cooked for us by Frankie's cool husband Bob, and so it was really ideal: Go out and learn all day, come back to camp to a hot meal, a cold beer, and a discussion of big picture ideas. My fellow teachers and I also played a lot of horseshoes and frisbee. To top it all off, when we got back to Bozeman yesterday, a group of us rented Jurassic Park and watched it over pizza and ale.

Next up: tomorrow I begin my Wildlife Ecology of Yellowstone course. Ought to be a similar high-octane experiential blast! More at the end of the week...

Labels: dinosaurs, fossils, montana, msse, yellowstone

Sorry for the long delay in posting here. Turns out they don't have Wi-Fi at Phantom Ranch.

After my time in Zion (did Angels Landing and a few other small hikes while there), I scooted down to Las Vegas, Nevada, to pick up my father and two brothers. They had flown in there, and after one day were already tired of the city. I was ready to leave five minutes after I got there, which is always how I feel about Vegas. Somehow, circumstances keep conspiring to bring me back there, though...

We drove out of the Basin & Range and up onto the Colorado Plateau, and spent the night at Cliff Dwellers, a lodge near Marble Canyon. I was really impressed with their food and drink. We had an amazing meal, washed down with several pitchers of Newcastle Brown Ale! In the morning, we gathered up our gear and put onto the river. Our trip consisted of two rafts outfitted with side tubes and motors and guides. One raft was entirely made up of a family from Charlotte, North Carolina, including the glass artist Wayland Cato, III. The Bentley's raft was augmented by a family from Littleton, Colorado, two oil men from Oklahoma, and a couple of veteran river rafters from northern California. It was a motley crew, but we started having fun immediately.

We launched at Lees Ferry, in the Kaibab Limestone, and then descended in both elevation and geologic time. At our first lunch stop, in the Coconino Formation, I was astonished at several synapsid reptile trackways protruding from the underside of the paleo-dune slipfaces overhead. I took some photos, but because of the aforementioned software issue, I won't be able to share them until I get back to DC in August. As the first couple of days went by, we just went deeper and deeper into the Paleozoic stratigraphy of the Colorado Plateau. Of all the formations, my favorite was the Bright Angel Shale, which has many beautiful colors in thin layers throughout (not to mention oodles of trace fossils). I was particularly pleased to play frisbee in a "cave" in the Redwall Limestone, a place that I have shown photographs of to my students, but never actually seen before. It's a HUGE cliff of the Redwall, and then this seemingly small cave etched into its base (and filled with sand), but the cave could easily swallow my building at NOVA: it's big!

At some point, we crossed a major fault, and were instantly dropped down about a billion years in geologic time. Once we got into the Grand Canyon Supergroup and the metamorphic and igneous basement rocks, my geologic interest really went wah-wah. The Vishnu Schist and Zoroaster Granite make a stunning contrast: really beautiful pink cutting across dark grey. I introduced my raft-mates to the idea of the Mazatzal Orogeny, and we discussed how boudinage forms. There were faults and folds galore: structural paradise. I loved it.

Did I mention the rapids? There were rapids. The water was COLD, thanks to Glen Canyon Dam(n). But the sun was hot, and we dried out quickly. Meals were gourmet, though the campsites were spartan (you had to poop in a box that got packed onto the raft each morning: leave no trace!). We slept out under the stars every night, sometimes dealing with blowing sand.

We took several hikes up side canyons to see waterfalls and go swimming. Several of these were good and physically challenging, which is what I wanted. I enjoyed swimming and playing "three-dimensional frisbee" in Havasu Creek, and doing cannonball jumps in the weird blue of the Little Colorado River.

The final day on the river, we came to the western section of the Canyon where recent lava flows (basalt) have cascaded over the rim and down into the canyon. This is famous for producing one of the toughest rapids in the whole Grand Canyon: Lava Falls. But it was awesome to float by and see umpteen gazillion columnar joints, and whole feeder canyons plugged up by basalt. Pretty cool!

Our final morning, we were helicoptered out of the Canyon to a ranch on the rim. This was my first time in a helicopter, and it was giddy and amazing. I want to fly! From the ranch, we transferred to small fixed-wing planes, and I said goodbye to my family. They went back to Vegas, and I flew back to Cliff Dwellers, where my Prius (and a shower!) awaited.

Labels: fossils, geology, grand canyon, minerals, primary structures, rivers, sediment, travel, volcano

I left Bozeman on Saturday morning, and drove for about seven hours. I headed south through Ennis, Montana, along the western side of the Madison Range, passing by the Madison Earthquake Site landslide (from the 1959 Hebgen Lake earthquake), and then south into Idaho. I went through Island Park, Idaho, site of the caldera of one of the three big recent eruptions of the Yellowstone volcanic center. Then into northern Utah, where I got a glimpse of the Great Salt Lake. I headed up into the Wasatch Range to spend the night, just east (and several thousand feet above) Ogden, Utah. I did some birding on the reservoir there, observing the mating rituals of both the woodcock (amazing humming noise produced during flying dives) and the western grebe (neck bobbing following by synchrnonous running across the water).

The next morning, I headed west from there, into the basin, across a range, into another basin, across another range -- you get the idea. I initially intended to go hunt for trilobite fossils in the Wheeler Shale in the House Range, but the 20-mile dirt road rattled me (quite literally) and I turned around after only four miles. I got spooked: what would happen to me if the Prius broke down out here? It's really quite desolate country. I've only ever had that feeling once before, when my Dad and I drove across the Namib Desert. It's a mix of agoraphobia and anxiety over feeling inept at repairing mechanical things, like Prii and other automobiles. I chickened out -- no trilobites for me. But there was a consolation in Great Basin National Park, which was where I headed that afternoon. I did a short hike there in the Snake Range, and toured Lehman Caverns there (my third guided cave tour in two weeks!). I had my best campsite of the trip at Great Basin: montane forest, with a gurgling stream running fifteen feet from my tent. Lovely.

When I woke up, I packed up the car and coasted downhill for eight miles into the town of Baker, Nevada, where I had a great breakfast and coffee at a little cafe there. Then up and over the Snake Range, and down the next valley to the west, south for 93 miles of some of the most empty country I've ever seen in America. In an hour and a half of driving, I saw only 20 vehicles. I crossed back into Utah, and then made my way south to the edge of the Colorado Plateau, and drove up into Zion National Park. Zion is a great canyon cut into a series of sedimentary rocks. The last time I was here, 13 years ago, I walked up the Narrows, and my first order of business was to repeat that hike. There's a new shuttle system in the park now, so after parking at my campsite, I hopped on a shuttle into the park and rode it to the end. I waded into the Virgin River and shuffled upstream. In the Narrows, the Virgin River has cut down through the Navajo Sandstone, but not quite down into the weaker underlying Kayenta Formation, and so the canyon is deep but narrow. (Downstream, when it gets deep enough to tap into the Kayenta, it undermines the sandstone cliffs, and the valley widens.) "Hiking" here is one of the more unique outdoor experiences I've had. Being immersed in the cool river, surrounded by towering rock walls -- it's magical. The further upriver you hike, the less people there are, and it's like a cathedral. I went up and around several entrenched meanders, and marvelled at the alcoves, cross-bedding, and variety of cobbles in the riverbed.

Today, I'm staying in the park and heading up to Angel's Landing, a legendary hike in its own right. Tomorrow morning, bright and early, I'm off to Las Vegas to pick up my Dad and brothers for our Grand Canyon rafting trip. Not sure if I'll be able to post again until after I get out.... late next week.

Labels: birdies, fossils, grand canyon, idaho, montana, national parks, stratigraphy, travel, utah

Roadtrip update:

Yesterday was a good one. I started off the day at the Sternberg Museum of Natural History in Hays, Kansas. I was the first one in the door, and had the place essentially to myself. Massive mosasaur skeletons, supercool Uintacrinus slabs, plesiosaurs, and all kinds of other neat stuff. They had some less spectacular mineral displays, but the locally-derived fossils were world class. I was very impressed.

Then, driving. I made good time when the wind wasn't trying to stop me, and listening to Bill Bryson's A Short History of Nearly Everything on my iPod, I crossed into Colorado. Eastern Colorado looks a lot like Kansas, of course, but before too long had passed, I got my first view of the Rockies in the distance, "rising from the plains." I got to the Denver area around 2pm, which meant I had plenty of time before the 7pm "Geography Goes Digital" event at the Denver Museum of Nature and Science (DMNS). So I headed southwest, towards Morrison, Colorado, and "Dinosaur Ridge." Dinosaur Ridge is a hairpin driving loop on/over the Dakota Hogback, showing Mesozoic sedimentary rocks shed off the Laramide Orogeny and into the Western Interior Seaway. There's an excellent display of dinosaur tracks, and lots of cool ripple marks, trace fossils, concretions, and stratigraphy. Looking out over the crisp dry air of the Denver Basin, I really felt like "Aha! I'm finally in the West!" It was a good feeling. After hiking and exploring there, I toodled into Morrison, Colorado, and went the Morrison Museum of Natural History. There, I had the terrific good luck to run into Matt Mossbrucker, who I mentioned reading about in Smithsonian magazine back in April. The museum's volunteers were on vacation, so I had the good fortune to have a personal tour from the director! Matt showed me a wealth of incredible fossils, including the type specimen of Stegosaurus, and footprints of baby Stegosaurus and Apatosaurus -- the latter tracks were the subject of the Smithsonian article. In case you (still) haven't read the article, it looks like these baby sauropods were capable of running on their hind legs like a basilisk lizard. Matt walked me through the logic, pointing at specific pieces of evidence on the massive slab of rock. Then we were out of time, because I had to get over to the DMNS for the "Geography Goes Digital" event.

At the DMNS, I was met by Kirk Johnson, the author of a book I mentioned here a month or so ago: Cruisin' the Fossil Freeway. My friend Michelle knows Kirk, and put us in touch. (Thanks, Michelle!) Kirk has been at the DMNS for more that fifteen years, starting as a curator of paleontology, and now as a vice-president. It was very cool of him to make time to see me. Immediately, Kirk introduced me to Bob Raynolds, the speaker for the "Geography Goes Digital" event. Bob and I talked a bit about geology and teaching, and then we scooted over to the Planetarium for the main event. I took a seat, leaned back and was amazed. It was like Google Earth on steroids; a feeling like looking down from the space station on Earth. Bob led us on an exploration of areas of the world that are showing the strain of coping with climate change. He has an astonishing amount of geographical knowledge (apparently, he has traveled to more than 50 countries to do geology) and it was a real treat to tour the planet with him and 150 of the DMNS's closest friends. Afterwards, Kirk took me and another friend-of-a-friend visitor on a tour of the museum. I saw the world's second-largest gold nugget, a massive crystal of rhodochrosite, and the incredible tour through time exhibit that Kirk put together when he first got to the museum. Starting with the Ediacaran, the exhibit went through time in a series of sub-exhibits. Each started with a diorama, and then showed the fossils that the diorama was based on. There were some INCREDIBLE fossils there -- absolute stunners. Kirk confided that's just how he wanted it -- not a thousand small fossils, but a few massive ones that just knock your socks off. It was very impressive. Around 10pm, I bade Kirk farewell, and left the museum. I drove up to Boulder, Colorado, and holed up in a hotel for the night.

I feel really lucky to have visited three amazing paleontological museums in one day, and to have had personal tours from the elite of Denver paleontology. Many thanks to Matt and Kirk for making time to show me around!

Now I'm off to check out Boulder, and maybe hike in the Flatirons above town. More later.

Labels: colorado, dinosaurs, fossils, kansas, minerals, travel

In preparation for my time out west this summer, my friend Michelle loaned me her copy of Cruisin' the Fossil Freeway, by Kirk Johnson and Ray Troll. It's a great read, and it's got me really psyched to start driving around the west, looking at geology. It also makes me wish for an informed local guide to clue me in to good outcrops.

I really liked this book. Johnson, a paleontologist with the Denver Museum of Nature & Science, narrates a 5,000-mile roadtrip travelogue about zipping around the western U.S. in search of fossils. Joining Johnson is Troll, a celebrated artist who makes clever art in several media. The book is light-hearted, well-informed, funny, and relaxed. I really liked it, and would recommend it to anyone with an interest in natural history, fossils, roadtripping, or Ray Troll's art.

Coincidentally, Geotimes reviewed the book in their May issue.
...And NPR beat them to it last fall.

Labels: books, colorado, fossils, kansas, nebraska, wyoming

Here's a few more photos from the recent field trip to the Massanutten Synclinorium in the northern Shenandoah Valley, Virginia.

Some more Arthrophycus (?) trace fossils in the Massanutten Formation:

Outcrop of the Massanutten Formation on Route 678, south of Waterlick, VA. Note that the bedding is dipping to the south (reflecting the overall "canoe"-shape to the structure of the Massanutten Synclinorium... this is the "bow" of the canoe...):

Shelly horizon in the Mahantango Formation. Mainly brachiopod debris, but also crinoid columnals:

Cross-bedding in the Martinsburg Formation's Bouma sequences. This is a sample I collected on Saturday. I sawed it open on Monday, then polished it and gave it a coat of clear acrylic. Sample length is about 5 cm:

Ditto. As above, we can see clear cross-bedding here, reflecting current flow in these ancient turbidites:

Bedding / cleavage relationships expressed at an instructive outcrop in the parking lot of a pet store north of Front Royal, Virginia. Bedding is clearly visible running subhorizontally across the picture, but the rock breaks vertically: a tectonically-induced cleavage:

You could hardly ask for a better outcrop to teach bedding / cleavage relationships. Here's a medium-sized anticline in the same outcrop (note quarter, center, for scale). It clearly displays a fan of cleavage orientations. Lovely!

Lastly, on that same note, here's a sample I collected fromthat locality, with bedding planes and cleavage planes highlighted through the magic of CorelDraw. The stripes you see on the face of the sample are formed by the intersection of bedding and cleavage planes, shown schematically in red:

Labels: appalachians, field trips, fossils, primary structures, valley and ridge, virginia

Last week, I mentioned some cool conglomerates I saw when NOVA adjunct instructor Chris Khourey and I did some field scouting. The main purpose of that trip was not to focus on the Culpeper Basin's boundary conglomerates, however, but the "Great Valley" of Virginia's Valley and Ridge province. The "Great Valley" is usually called the Shenandoah Valley in Virginia, because the Shenandoah River flows north through it. (Topographically, it continues north into Maryland, but the Shenandoah River isn't found there.) Sitting in the middle of the valley is a mountain range, Massanutten Mountain. And in the middle of Massanutten, there is another valley, the Fort Valley. As you can see below, Massanutten is a fence-like ridge separating the higher Fort Valley from the lower Shenandoah Valley:

In fact, rumor has it that the name "Massanutten" is a native American term for "basket." This describes the overall shape of the mountain/valley quite well. It probably won't surprise you to learn that this valley-in-a-mountain-in-a-valley pattern is due to differential weathering of folded sedimentary layers. In fact, the entire Great Valley is one big downturned fold, a syncline. Actually, it's not a perfectly smooth fold -- there are some wrinkles and minor folds within the overall down-turned structure, so we call it a synclinorium. The oldest rocks are therefore at the eastern and western edges of the Great Valley, and the youngest rocks are at the center of the Massanutten Synclinorium, up in the Fort Valley. It turns out that some of these rock layers are easily eroded, and some are tough. Of particular note is the Massanutten Sandstone, a quartz-rich, well-indurated rock that is responsible for the ridges of Massanutten Mountain. It weathers away more slowly than the shales and carbonates (limestones) above and below it. Here's a cross-section view to show how the subterranean structure influences the surface topography:

The map view up above (using Google Maps' super-cool new terrain feature) and this cross-section also show the difference in landscape texture (and geologic cause) of the Blue Ridge province in the SE corner of the images.

In discussing the geology of the area, I'm going to mix my pictures from Thursday's scouting expedition with photos from Saturday's actual field trip with my Audubon class.

Let's start at the beginning. The first stop was in the Conococheague Formation, a late Cambrian limestone. Our field trip stopped at a nice exposure near Mulberry Run, west of Strasburg, VA. Here's the crew looking close at the outcrop, and trying out their geo-interpretive field skills for the first time:

Albert tests the outcrop with some dilute hydrochloric acid. It fizzes!

Soon, we spot the first of several stromatolites:

There are also some nice spherical grains of calcite called ooids (or ooliths). These form in wave-influenced carbonate banks today, like the Bahamas.

Interpretation of this environment then? Looks like a nice passive margin, far from any major terrigenous inputs (i.e. mud or sand). Warm tropical temperatures leading to the chemical precipitation of lime mud from seawater.

What comes next? On to stop #2, the Tumbling Run section* south of Strasburg, we see a nice long exposure of the New Market, Lincolnshire, and Edinburg Formations, a series of Ordovician limestones, all dipping nicely towards the axis of the synclinorium. (Last semester, one of my Honors students looked at silicified trilobites in the Edinburg Formation.) As you walk downhill (and up-section), you see a change in the limestones. They get darker in color, and they start splitting into thin sheets along clay-rich layers. Uh-oh, we're getting an increasing clastic influence on these sedimentary rocks. They no longer record pristine, Bahamas-type environments. Now the limestone is mixing with shale. Where is all that mud coming from? A hint may be found in several bentonite layers, weathered volcanic ash deposits. There's some volcanoes getting closer to the area, it looks like.

In the late Ordovician, the east coast of North America experienced the first of three episodes of Appalchian mountain-building. Geologists infer that the Taconian Orogeny was caused by the collision of a volcanic island arc (like modern day Indonesia) with the east coast. The Tumbling Run section shows well the increasing clastic influence of the growing Taconian Mountains to the east.

It's also good for some small but interesting tectonic structures. Check out this conjugate pair of en echelon tension gash arrays:

The black nodules you see along bedding in the above image are flint nodules, very characteristic of the Lincolnshire Formation. If you get close to them, you'll find that they exhibit different mechanical properties than the limestone that surrounds them. They are more likely to break (brittle behavior) than flow (ductile behavior):

But let's get back to the stratigraphy, shall we? (It just doesn't do to get distracted by these minor structures!) Our next stop was to look at the Oranda Formation (calcareous shale), indicating heavy clastic influence (but still a bit of carbonate). Then, after a lovely lunch at the Strasburg Emporium, we headed off to the Buzzard Rock Trail, to look at the Martinsburg Formation. The Martinsburg is a nice thick batch of fine sand and mud interpreted as turbidite deposits. Various pieces of the Bouma sequence can be seen throughout the formation, including graded beds, ripple marks, and cross-bedding. This picture conveys these alternating lithologies, representing fluctuating current strength as turbidity currents periodically brought coarser sediment into the deep (low-oxygen, as indicated by the dark color) basin.

Now, keep in mind that all these sedimentary layers later got folded during the final phase of Appalachian mountain-building, the Alleghenian ("Alleghany") Orogeny. At that same time of intense deformation, some of these mud layers began to convert to slate. The outcrop on the Buzzard Rock Trail shows this pretty well, in spite of being covered by lichen, algae, moss, and other horrible rock-obscuring growths:

The sandy layers outcrop as stiff, blocky strata. But look to the right of the quarter: in the muddy layers, a penetrative cleavage has developed, subperpendicular to the compressive stress. Here, let me draw for you what I saw at this outcrop:

The clay minerals in the mud are more susceptible to being alligned by tectonic forces than the grains of sand in the coarser layers. So the shaley intervals exhibit a more pronounced cleavage than do the sandy intervals.

But again, I'm getting distracted by the tectonic overprinting! This trip is supposed to be about stratigraphy, pure and simple. Doggone it! Okay, moral of the Martinsburg: no more carbonate by the late Ordovician. Instead, this sedimentary basin is getting filled with clastic debris shed off the Taconian Mountains** to the east.

Next layer up is the Massanutten Formation: mainly quartz sandstone, but also some quartz pebble conglomerate. We see it by entering the "basket" via a water gap near Waterlick, VA. Driving south (uphill) along Passage Creek, we were soon surrounded by looming cliffs of quartzite. It represents fluvial and beach facies as the depositional basin was filled to the brim. Here's a boulder of the conglomeratic portion:

Here's some nice cross-beds in the sandy portion exposed near Blue Hole, about 4 miles south of Waterlick, VA:

Other Massanutten Formation features include some fossils. Here's some poorly-preserved brachiopod external molds:

And here's some Arthophycus horizontal trace fossils, probably made by polycheate worms:

Okay, I can't resist this tectonic structure: an awesome anticline exposed along the Veatch Gap Trail (eastern part of the synclinorium, where a small anticline in the Massanutten Formation is superimposed on the larger synclinal pattern):

Beyond the Massanutten Formation, we are in the Fort Valley proper, inside the "canoe" shape of the Massanutten Mountain ridge system. Next layer up is some upper Silurian / lower Devonian carbonates, representing a return to passive margin sedimentation after the end of the Taconian Orogeny and the erosional beveling of those ancient mountains. Unfortunately, there are no good places to stop on the narrow Fort Valley Road, so I don't have a picture of them to share. Trust me, though: they're there.

The next good stops are of Devonian shales. There's some nice ones exposed across the road from Elizabeth Furnace. More mud? From whence does it come? We interpret this again as the onset of an orogeny, in this case the Devonian-aged Acadian Orogeny, which dumped a big thick wedge of sediment into the Appalachian Basin. Here's a shot of the Needmore Formation, one of these shales with distinctive trace fossils highlighted by iron oxide:

The overlying Mahantango Formation (Devonian) is a siltstone that bears a decent number of body fossils, like these brachiopods:

Here's something that may be the back of a trilobite (if I'm not imagining the lobe to the left of the central line of knobs), or maybe a crinoid (if the "central" line is all there is):

Here's what appears to be the (vertically-oriented) trace fossil Daedalus, which I learned for the first time this spring in Silurian rocks near Buffalo, New York:

Finally, at the top of the stack, near Seven Fountains, there are exposures of more bentonite, in this case the Tioga Bentontite, a major stratigraphic marker bed throughout the Appalachians. Here's a shot of the bentonite exposure on the Fort Valley Road near Seven Fountains:

Here's Chris looking at the outcrop:

To summarize the Fort Valley portion of the story: after the Taconian Orogeny ends, we get a brief period of tectonic calm and passive margin sedimentation (carbonate), and then a return to orogenically-induced clastic sedimentation (augmented with volcanic eruptions). In the sedimentary sequence of the Massanutten Synclinorium, this records the onset of the Acadian Orogeny. The actual deformation of all these sedimentary horizons into a synclinorium shape was accomplished by the Alleghenian Orogeny: the much bigger mountian-building episode triggered with Africa and North America collided in the latest Paleozoic.

Hope you enjoyed joining us on this trip. Virginia's got some great geology, eh?

* For the Tumbling Run section, I highly recommend this excellent field guide:

Fichter, Lynn S., and Diecchio, Richard J., 1986, "The Taconic sequence in the northern Shenandoah Valley, Virginia." In: Geological Society of American Centennial Field Guide - Southeastern Section, p.73-78.

** Note I don't say "Taconic." The Taconic Mountains are a modern topographic feature in New York. They exhibit Taconian rocks well, and the orogeny is named for them, but the Ordovician Taconian Mountains would have been much bigger and more areally extensive.

Labels: fossils, primary structures, sediment, stratigraphy, structure, teaching, valley and ridge

This one's a good one to assign to Historical Geology students who don't have time to read The Map That Changed The World. It's part of the series "On the Shoulders of Giants" by NASA's Earth Observatory: William Smith.

I love the way these pages are laid out: a single column of text with illustrations of different sizes and dimensions interspersed with the content. It's like a Dorling Kindersley book. NASA must have some good web designers on the payroll.

Labels: books, fossils, geologists, history, stratigraphy

Labels: dinosaurs, fossils, geologists

Holy cow. Check out this dude, who's seeing dragon fossils in Cambrian rock slabs in Utah (video below). You probably don't want to waste half an hour watching the whole thing, but it's worth 5 minutes or so to get a flavor for how imagination and pseudoscience can yield some interesting results. Also, it will give you a new appreciation for running spellcheck.

My favorite lingo from the presentation is "duckbill horseshoe snoutic configuration" although I am also partial to the presenter's elucidation of "internal growth genetic substructure of the zoria repeating biological structure."

Labels: fossils, pseudoscience

On Wednesday, two students and I participated in an excellent field trip examining the sequence stratigraphy of the Niagara region. We saw uppermost Ordovician rocks (the Queenston Formation) and then a dozen Silurian formations, some of them only 3 meters thick, stacked atop on another in a stereotypical layer cake fashion.

The trip was led by Carl Brett, who did a great job. I wanted to showcase here a few of the photos I took that day. Here's Carl showing us Arthophycus trace fossils (interpreted to be the burrows of polycheate worms):

At Outwater Park, we found fossil stromatoporoid reefs. Stromatoporoids were primitive, layered sponges. These ones show glacial striations across their surface, a result of the outcrop being scraped by glaciers during the recent Ice Ages:

At another stop (on Lockport Junction Road) , there was a Leperditia ostracode-rich layer. Ostracodes are small arthopods, kind of like krill, but with bean-shaped shells.

At Pekin Hill, we looked at the Goat Island Formation, which showed ripped-up stromatoporoids deposited within it.

Here's a stromatoporoid that tumbled loose from the slope. I'm bringing this one back to Annandale to use as a teaching specimen. Note the upward-bulging dome of the stromatoporoid's internal layers.

One of our most amazing stops was hiking up into the Niagara Gorge. This is at the downstream end of the Niagara Escarpment, where the Falls once were. The adjacent town is Lewiston.

Here's Laura and Victoria in the Gorge, overlooking the Niagara River:

Now for some fossils from the Rochester Shale and other units exposed in the Gorge. Carl brought these out to show us what we might find. Here's a mouthwatering slab showing Dalmanites trilobites:

And a golf-ball sized cystoid (relative of crinoids, blastoids, and other echinoderms):

He had some Lingula dwelling traces, too. Lingula is a common inarticulate brachiopod that dwells / dwelled in vertical burrows beneath the seafloor mud:

Here's a shot of a crinoidal grainstone. This limestone is almost entirely made up of "sand" generated by broken up crinoid skeletons:

Some spectacular trace fossils (ichno-genus unknown) on a slab that was catching the rays of the sun just right:

And a close-up of the same slab:

And lastly, a nice slab showing tool marks:

It was really a great trip -- perfect weather, fascinating rocks, good company, and I felt nice and tired at the end of the day.

Labels: fossils, meetings, new york, nova, primary structures, sediment, silurian

This is the image on the cover of the April 2008 issue of Geology:

Wow, eh? Here's what they have to say about it: "The image shows a perfectly preserved Devonian phacopid trilobite, which was collected at Hamar Laghdad in Morocco (cephalon is 10.2 mm diameter). The shell is silicified with a high iron content, while the lenses retained their original calcitic composition, hence the color difference. This can probably be explained by the different crystal size and the porosity of the shell. Photo by: Christian Klug and Hartmut Schulze."

Labels: art, fossils, minerals

Walking around the mid-Atlantic Piedmont (my home territory), we find a lot of these fellows lying around. They are cobbles of the Antietam Formation (a Cambrian quartzite from the Blue Ridge) which were weathered out and transported eastwards (~60 miles or so, as you can probably deduce from their rounding). They were then deposited as part of the Potomac Group (Cretaceous river gravels draped over the metamorphic rocks of the Piedmont; preserved today on Piedmont hilltops and as the basal layer of the Coastal Plain). The cobbles display the vertical trace fossil "Skolithos" (sometimes spelled "Skolithus"), usually interpreted as a worm burrow. Each burrow is 2-3 mm in diameter. Here I've got a few photos: a cross-sectional view, a "plan" view, and a shot of one of the boulders in a stream in Arlington, VA.

Labels: blue ridge, coastal plain, fossils, piedmont, sediment

The New York Times has a piece this morning about dinosaur tourism in Argentinian Patagonia. Basically the gist of the article is that Jorge Calvo, an Argentinian geologist & paleontologist, is encouraging tourists to get involved in excavating dinosaur fossils as a way of paying the bills and getting the beasts out of the ground. Not everyone agrees with the approach, and the article quotes another Argentinian paleontologist who call's Calvo's tourist-extracted fossils "hostages."

It's also accompanied by a slideshow of photos.

Labels: dinosaurs, fossils, south america, tourism

National Geographic has an article online about a cool new fossil from Spitsbergen, Svalbard (the Arctic island achipelago belonging to Norway). It's a plesiosaur, a marine reptile from the Jurassic period of geologic time. The front flipper is almost ten feet (3 m) long! The online article includes a picture gallery (the site, the fossils, and National Geographic's beautiful reconstructions).

Labels: fossils, norway, websites

Yesterday I found my cat Lola pondering a fish fossil from the Eocene Green River Formation. Because she's more of an Appalchian cat, I explained to her that this fish was preserved in flat-lying lacustrine deposits in southwestern Wyoming. The formation is notable for bearing impressions/carbon-films of many species, essentially an entire fossil lake ecosystem. She seemed interested, so I referred her to a travel article I wrote on the topic once for Geotimes. She padded off to read it.

Later, Lola conveyed to me that during a cat nap, she dreamt of her own fossilization in the Green River Formation style:

I replied, as I'm sure you would, that I'm not into the idea of pet cryo-preservation or taxidermy, and that I hoped she'd remain unfossilized for the foreseable future. That made her purr. I also reminded her that most cats don't like water, and hence are unlikely to fossilize in their usual habitat.

Ahh, Photoshop: even better than Facebook for wasting away the hours...

Labels: art, fossils, humor, lola

This is an amphibian that you wouldn't want to meet in a dark alley: Beelzebufo, a monster fossil frog from Cretaceous sediments in Madagascar. It resembles the ceratophryine family of horned toads (sometimes dubbed "pac man frogs") that are now unique to South America, which the authors of a new study published in the Proceedings of the National Academy of Sciences.

Here, artist Luci Betti-Nash's whimiscal painting of Beelzebufo has it facing extant species Mantidactylus guttulatus, the largest frog in modern-day Madagascar.

The discovery of the big croaker suggests that South America and Madagascar were linked landmasses for much later than previously deduced from other lines of evidence. However, the newly-implied gap in time is substantial. Previously, it was inferred that the two landmasses separated 120 million years ago (Aptian), but the interpretation of this new fossil is that it must have been after 80 million years ago (Campanian). I'm not sure I buy that huge jump in separation dates based on a single genus of fossil frog: 40 million years is a substantial amount of time. On the other hand, sometimes "small" pieces of evidence like this lead to the development of new paradigms in scientific thinking. It has the potential to be the proverbial thread which unravels the sweater.

My caution: It's important to remember that fossils which resemble one another don't necessarily imply a continuous population: there's convergent evolution to consider, as well as the possibility of a highly conserved morphology over time. Both of these phenomena could maintain similar looking populations of "pac-man-esque" frogs on unconnected landmasses. And, I suppose, there's even the less-likely possibility of a "rafting" incident, where a few individuals ride a mass of vegetation across the ocean(s) from South America to Madagascar well after the two have separated. It happened to iguanas, after all: getting from South America to the Galapagos. Actually, with amphibians, their eggs can sometimes hitch a ride on bird feet too, colonizing distant new areas with ease. I'd like to know more about the presence or absence of relevant fossil frogs in Africa during the Cretaceous in order to better evaluate this new interpretation.

Read more about it in this New Scientist article. (I couldn't find the "cited" original article in PNAS, for some reason.)

Labels: amphibians, evolution, fossils, plate tectonics

We've had a cold week in the mid-Atlantic this week, and increasingly my thoughts turn to warmer conditions and the summer. Last year, this year, and next year, I'm scheduling time in Bozeman, Montana, to take classes at Montana State University. I'm working on a second master's degree in science education. It's a pretty cool program which mixes educational practice and "action research" with science elective courses, including plenty of geology offerings.

Today in the blog, I thought I would begin the process of share some images from my time out west last summer. I'll start with the Bridger Range, north of Bozeman. Here's a meadow where we parked the vans before hiking up into the hills on Dave Lageson's excellent Alpine Field Studies seminar:


Once we had huffed and puffed up about tree line, we started to see some pretty cool geology. Here for instance, you can see tilted, folded, faulted Mississippian-aged strata that have been carved into by a glacier. A few minutes after this photo was taken, the class walked straight down into this cirque and climbed up the other side: there's some serious gravity-fighting going on with a route like that. We had lunch on the other side at the top of that orange-colored chute in the upper left:


In the photo below, my hands bracket a tilted zone of paleo-karst in the Mississippian-aged Madison Limestone. With massive limestone above and below, this orangey zone speaks of a time when the limestone deposits of this area were exposed at the surface. Caves and sinkholes developed, as did an iron-rich paleo-soil. It probably looked a lot like modern-day Florida, without the strip malls and retirees. Later, the sea returned and deposited more limestone on top. The paleo-karst is obvious because it contains big blocks of limestone from cave-roof collapse, and is stained by hematite and limonite:


Fellow DC resident and geology educator Nez Nesbitt follows Dave Lageson (the instructor) south along the crest of the range. The drop to either side was substantial, including the headwall of a cirque to the left (east). The loose scree we were walking over added an additional challenge:

In all that scree on the slope we're walking over, there were some cool fossils, including this awesome crinoid calyx ("head" region) - front and back views:


Atop a peak, we paused for a break, and Dave unfurled his Tibetan prayer flags to flap in the wind. I was struck by how a simple little string of cloth imparted a really cool aesthetic to the mountain-top:


This is the trail leading down Sacagawea Cirque. There's some substantial switchbacking going on here:


Here's me atop the highest peak in the Bridger Range, Sacagawea Peak. The views are pretty good from up there:


The class spent the next day mapping glacial landforms in Sacagawea Cirque: it was fun, but I didn't take as many pictures then. When the mapping was over, I prowled through the lateral moraines for fossiliferous chunks of limestone, and found some awesome rugose corals and other treasures. These samples now reside in the NOVA Historical Geology teaching collection.

Labels: fossils, geology, glacial landforms, montana, msse, structure

Labels: canada, fossils, humor, tv

A cool new pterosaur fossil was reported this week in the Proceedings of the National Academy of Sciences. Like so many interesting fossils of recent years, it's come out of China's Liaoning Province, which must be one big Lagerstatte. Unlike previously discovered pterosaurs, it had strongly curled toes, which indicate that it spent some of its time in trees, clutching cylindrical branches. It's small, too: really small, with a wingspan of only 25 cm, about the same as a barn swallow. Even so, it appears to be related (in a basal, primitive way) to the largest pterosaurs that ever lived, giants like Quetzalcoatlus.

Labels: china, fossils

Saw this video yesterday on the "How Stuff Works" website. It shows a crazy number of mammoth fossils being unearthed in Siberia (due to thawing of the permafrost there). I was kind of astonished how casually the fossils were being treated: at one point, a Russian scientist takes two mammoth teeth and grinds them together with vegetation in between, to demonstrate how they chewed. This strikes me as kind of rough treatment for specimens like this.

Labels: fossils, global warming, tv

OK, if you watch LOST and haven't seen this week's episode yet, then go do something else. Honestly, what are you doing reading geology blogs anyhow?? There are more important things to be doing... Like catching up on LOST.


(Are you gone yet? DON'T KEEP READING. I warned you. Don't.)


For those of you who watch LOST, umm, wow. Thursday night was what the season opener should have been. Major new insights, major new questions. And: son of a gun, some of them have geological tie-ins. Who'd-a thunk it?


I mean, those of us who've made it through Season 2 know that the island has a weird magnetic anomaly, a feature which not only crashed Oceanic flight 815, but also apparently shields the island from outside observation. Geotimes even wrote a piece on this geological plotline. At the end of Season 2, a team of (apparently) polar scientists in the employ of Penny Widmore even remotely detect a magnetic pulse from the island.


Among the new insights from this week's episode: the location of a sunken Oceanic 815, complete with tail section and wedding-ring-less pilot Greg Grunberg. And not only is it discovered by robotic submersibles, but they show a map of a major subduction zone to show where they found the plane. (See below for a screen capture.) But is it really the real Ocean 815? Or a decoy? Regardless, when was the last time the Sunda Trench appeared in a fictional TV show?

Labels: fossils, plate tectonics, tv

Last week, I put up some pictures of the folded strata at "the Whaleback" outside of Shamokin, Pennsylvania. Today, I'll augment those with some images of the fossils found at that site and at another outcrop of the Llewellyn Formation near St. Clair, Pennsylvania. Here's a fern impression to start with:

Labels: appalachians, fossils, pennsylvania

An interesting piece on NPR discusses how joshua trees (Yucca brevifolia) will react to climate change. It revealed a fact I had not previously recognized: that during the Pleistocene, joshua trees habitat expanded thanks to the digestive efforts of the Shasta ground sloth (Nothrotheriops shastensis). Sloth dung deposits are full of j-tree nuts, and since the sloths expired 13,000 years ago, the trees haven't been able to move as far or as fast. Half of their current habitat in California and Nevada may be too hot and too dry within the next 50 to 100 years. The graphic above is from NPR, which produced the story as part of their "Climate Connections" series.

Labels: california, fossils, global warming, national parks

Last weekend, I went to see Sea Monsters 3D: a Prehistoric Adventure, an IMAX movie about Mesozoic marine reptiles. It's playing in the IMAX theater down at the Smithsonian's Natural History Museum.

I kinda liked it. I must admit, I'm a sucker for a Tylosaurus leaping out of the water with a writhing Squalicorax shark in its mouth. I was disappointed by T-rex: Back to the Cretaceous in the same venue, so it was pleasing to check out this feature's relative quality. Unlike the unabashed fiction of T-rex (the heroine inhales hallucinogenic dust from a dinosaur egg, causing her to see a museum's specimens as they were in life), Sea Monsters is more of a straight shooter. It examines the story of the life of a female Dolichorhynchops in the Cretaceous seas of the Western Interior Seaway. As she grows up, you see nearby predators and relatives, and eventually encounter their fossils. The fossils are discovered in the modern day, sometimes in the early 2000s, sometimes back around the turn of the previous century. The techniques of field paleontology, I noted, don't seem to have changed much during that time.


Anyhow, the various creatures lived and ate each other and died and were fossilized, and the various paleontologists, driving their model Ts or their Suzukis, drive out into Kansas or Montana or the Dakotas and excavate these ancient creatures. These "paleontologists" are patently actors, and not especially good ones at that. Six Feet Under, it's not. But the digitally-recreated scenes of the Mesozoic seas were pretty cool. I liked seeing ammonites squirt ink on the Dolichorhynchops ("Dollys," in the film's parlance), and I liked seeing a lone placodont swim weirdly towards the camera. Because the movie is in 3D, you have to wear dorky glasses (it's dark; no one can see), but that means that the toothy snouts of Styxosaurus and its ilk poke out right into (seemingly) the center of the theater. Pretty dang cool.

Labels: fossils, movies

A paper in the new issue of Proceedings of the Royal Society announces the discovery of fossil evidence of the largest rodent yet recorded by science. The fossil reported is a skull, found in Uruguay. Of course, South America is home to the largest living rodent (the capybara, Hydrochoerus hydrochaeris), and it's no surprise that the continent should also have been home to the largest fossil rodent. The reason is that South America was a hotbed of mammalian evolution from about 65 million years ago (Ma), when it separated from North America, until about 3 Ma, when it reconnected with North America via the narrow Isthmus of Panama.

The new species, dubbed Josephoartigasia monesi, is closely related to another large extinct rodent called Phoberomys pattersoni as well as an extant (still living) species known as a pacarana (Dinomys branickii). The image at right, from the paper, shows a reconstruction of the head of J. monesi and a comparison with a pacarana.

P. pattersoni (from Venezuela) is estimated to have weighed about 700 kg, while J. monesi's bulk (extrapolated from the relative size of the skull) must have been about 1000 kg, a full metric ton.

As a continent hosting an independent trajectory of mammalian evolution, South America offers a beautiful contrast to Australia. Both continents were isolated from other continents for tens of millions of years, and their particular blend of mammals (& other species) evolved into unique & interesting forms. The South American experiment ended when it reconnected to North America at 3 Ma. At that time, mammals from North America trooped southward through Panama, and mammals from South America trooped northward. This flux of biodiversity is referred to as the Great American Faunal Interchange, and it dramatically reshaped South America's mammal assemblage. Saber-toothed cats (Smilodon sp.) was one of the turistas from the north, and it likely fed on big fat critters like J. monesi.

Other southward-bound groups included deer, bears, squirrels, rabbits, raccoons, and camelids (which went on to diversify into llamas & their kin). Northward-bound groups colonizing North America were fewer in number: the armadillos, the opossum, ground sloths (now extinct), and porcupines. Today, about 50% of South American mammal species have a North American origin, while only 20% of North American mammals have a South American origin. One of the reasons suggested for this lopsided distribution was that North America had been periodically connected to Eurasia (both east and west) via landbridges during the Cenozoic, and therefore North American mammals had been continually tested against the biggest continent's most competitive species. The North American mammals had already been forced to prove their mettle. South American mammals were living a life of blissful ignorance & luxury, and they experienced a rude awakening when their neighbors from the North came stampeding in. The competition between the two groups resulted in a lot of extinctions, and one of those appears to have been J. monesi. The fossils were found in a sedimentary unit usually interpreted to be about 2 Ma.

The image below shows the sheer size of the J. monesi skull by comparing it to a handheld rat. (Maybe a Norway rat? I can't tell, and the image from New Scientist doesn't specify the species.) It's a pretty extreme difference, of the same order of magnitude as the difference between an elephant and a hyrax.


Evolution can be really fruitful given a sufficient easing of competitive pressure. Island biogeography gives us some weird creatures (Komodo dragons, dwarf elephants, and Homo florensis come to mind as three Indonesian examples) if isolation is maintained over time. This new discovery from South America confirms the larger pattern by showing us that gigantism has happened in the rodent family, too. Discoveries like this (and the recent giant ape reported from China) prompt me to imagine other possible evolutionary trajectories: what about giant bats, or mouse-sized whales? Could evolution produce arboreal deer, or bears the size of Chihuahuas? I welcome your thoughts & creative speculations on potential record-breaking mammals.

Reference: Rinderknecht, Andres, and Blanco, R. Ernesto. The largest fossil rodent. Proceedings of the Royal Society, B. doi:10.1098/rspb.2007.1645 Published online.

For those without a subscription to the Proceedings, you can check out New Scientist's write-up of the research here.

Labels: evolution, fossils

The Smithsonian's department of paleobiology has a webpage devoted to displaying some art that was used in some old scientific papers on fossils. There's a beautiful variety of images there, like this frontal view of a Triceratops skull that was used to prepare a lithograph, which then appeared in a paper by legendary paleontologist Othniel Charles Marsh (archnemesis of Edward Drinker Cope). Check out the full variety of art here.

Labels: art, fossils, smithsonian, websites

In the week between Christmas and New Years, my friend Casey and I took a trip to Northern Ireland. We stayed with her friends Jodie and Rory in Portadown, and on our first full day, Jodie took us out to Armagh (pronounced "Ar-maa"), where she teaches at a primary school. Saint Patrick apparently decided that Armagh was going to be the seat of Irish faith, and he decreed that the Archbishop of Armagh would have preeminence over the rest of Ireland. Of course, Northern Ireland is a land still strongly divided along religious lines. Though it's no longer violent, there is still strong "us and them" sentiment among the Northern Irish people I spoke to. Jodie took us to visit Armagh's two cathedrals: one Catholic, one Protestant. They occupy the two highest hills in town (of course!).







Flatscreen television monitors inside the Catholic cathedral, so that worshippers can see what's going on behind those massive columns.










I was delighted to note a bunch of geological details in the two buildings. This image is of the limestone that makes up the exterior of the Catholic cathedral. It's full of fossils. Here's some spiral-shelled creature. Not sure what exactly. Width of fossil is about 1 inch.












Fossil coral colony on the exterior of the Catholic cathedral. Pound coin for scale.











The Protestant cathedral (Church of Ireland) is made of a greater variety of stones. Most of it is sandstone, and the sandstone hosts deposits of iron oxide (hematite) in precipitated horizons called Liesegang banding. Though it looks strongly layered, the Liesegang banding is not sedimentary bedding. In this block, bedding is horizontal, and the Liesegang banding was deposited by groundwater at an angle to the bedding. Pound coin for scale.


The lower part of the Protestant cathedral is made of conglomerate/breccia. The large clasts are fairly angular, indicating that they did not travel far from their source area before they were deposited. This makes it more a breccia than a conglomerate. Unlike a lot of true breccias, however, this rock is pretty well stratified (layered), indicating that it was deposited by moving water: a characteristic of conglomerates. Pound coin for scale.



Here's one particular clast from the conglomeratic lower part of the Protestant cathedral is made of conglomerate/breccia. In it you can see fossil fragments, apparently of the same coral visible in the Catholic cathedral's stone. Pound coin for scale.






Of greatest interest to me was the fact that James Ussher was the head of the Church of Ireland (the full title is "Primate of All Ireland") from 1625 until 1656. As I mentioned earlier, this means that he was the Archbishop of Armagh. Ussher has a reputation as the most scholarly of the historial archbishops, and he is particularly known to geologists because he attempted to calculate the age of the Earth using the Bible. By estimating generational times and tracking geneaological lineages in Scripture, Ussher proposed that moment of the Earth's creation was the evening immediately before Sunday, October 23, 4004, B.C. It is from his work that the specific notion of a young Earth arose. According to Ussher and his subsequent legions of young Earth creationists, our planet is only 6000 years old (well, 6011 years, to be precise.) Of course, this caused some tension with geologists of the time like James Hutton, who realized that if the uniformitarian concept is correct, the Earth must be vastly older than 6000 years (or, to be precise, 5750 years old at the time Hutton himself was mulling it all over in the mid-1700s). Later discoveries by the many geologists inspired by Hutton, in particular that of radioactive decay, provide quantitative evidence that the Earth is in fact much older than 6000 years. Three different lead isotope systems, for instance, provide ratios of radiogenic lead to non-radiogenic lead that suggest the Earth is about 4.5 billion years old. That's approximately 6 million times older than Ussher calculated -- a vast, vast difference. In spite of the overwhelming physical evidence for an ancient Earth, I still find that many students enter my classes with a perception that the Earth is less than 10,000 years old. I have James Ussher to thank for that. It was a pleasant moment for me to visit his cathedral and ponder his lasting effects.

Labels: armagh, fossils, geology, northern ireland, ussher

Gigantopithecus blacki is the name of an extinct species of giant ape that existed in China 300,00 years ago. It was between 9 and 10 feet tall! Imagine seeing that as an early human expanding into that area -- easily imaginable as the source of our legends about giants. Because it apparently ate bamboo and fruit, it may have competed with pandas, too.

Labels: fossils