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:

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

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 girlfriend 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