The NOVA Geology Department has organized a Wilderness First Aid (WFA) Training Session for May 22-23 here on campus. Our goal is to give our field trip leaders (geology and otherwise) the skills they need to handle medical emergencies. If you're interested in getting WFA Training, please join us. The cost for the 2-day certification course is $250. Contact Nancy Chamberlain for registration information.

Labels: field trips, nova

Snowball Earth. The Pleistocene Ice Age was the proving ground for our species. But an earlier episode of glaciation, dubbed Snowball Earth, stretches our conception of what the limits of climate change are: the ice reached from the Earth's poles to its equator! Scientists infer that the freezing event was ended due to volcano-induced global warming. The course examines the geologic, chemical, and biologic evidence for Snowball Earth. This course meets 8/4 to 8/10: three evenings (MWF, 6-9pm) and one Saturday field trip to local Snowball glacial deposits. GOL 299, section 071N: 2 credits. More details

Labels: appalachians, geology, nova, teaching

At the end of the northeastern GSA meeting yesterday, we loaded our NOVA crew up in the van and drove up to see Niagara Falls itslef. Here's the students (Laura, Victoria, Spencer, and Jason) at the American Falls. There were huge masses of ice built up down in the Gorge as the mist froze: quite a scene. The place was practically empty though -- very few visitors. Good to get up here and check it out. The flow you see here is 25% of the Niagara River's actual discharge. 75% gets diverted into electricity-generating projects on both the US and the Canadian sides of the river. (The buildings you see in the background are in Canada.)

We have another half-dozen talks to go to this morning, but then we hit the road back to NOVA. I just looked out the window -- and there's a couple inches of fresh snow on the ground!

Labels: falls, nova, water resources

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

On Tuesday afternoon, four students and I drove from Annandale, VA, up to Buffalo, NY, for the NE section meeting of the Geological Society of America. On the way, we crossed the Pennsylvanian Appalachians, and pulled over to examine some beautiful redbed exposures on the Pennsylvania Turnpike. I think these are in the Hampshire Formation, but I could easily be wrong about that, considering I've never been here before. Here's a few photos. First, some beautifully rhythmic alternations between sand and mud, now preserved as alternating layers of sandstone and mudstone:

Then, some nice "ball and pillow" structures, as heavy sand sank downward into squishy mud. In places, the mud skooshes upward in "flames":

And lastly and most amazingly (for me), some awesome exposures of flute casts. These are erosional scours into a layer of sediment by a current, which then fills in the scours (called "flutes") with sand, making these flute casts on the underside of the overlying layer of sand:

The flutes "point" upstream, and open up (and shallow) in the downstream direction. More later!

Labels: appalachians, meetings, nova, pennsylvania, primary structures, sediment, teaching

Cool folds (in metamorphic foliation) in this sample:

Here's the real prize: a big chunk of peridotite (upper right) that's partly surrounded in a crinkly foliated matrix of chlorite schist (lower left):

I'm off to Buffalo, NY today with four Honors students to attend the northeastern section meeting of the Geological Society of America. If anyone from the geoblogosphere happens to be up there, I hope you'll say "howdy." Posting may be sporadic over the next few days... we'll see what the Internet connectivity issue is like up there.

Labels: appalachians, iapetus, meetings, nova, piedmont

Check out yesterday's excellent post by Geotripper about the recent arrival at Earth of light from a supernova that happened 7.5 billion years ago.

Labels: blogs, planetary geology

Three days ago, NPR aired a segment about how geology students can make lots of money.

Here's the description: All Things Considered, March 21, 2008. With the price of oil, gold and other metals at near record levels, these are heady times at the Colorado School of Mines. Employers are falling all over themselves to hire new graduates. Who'd have thought that being a geologist would make you so popular - and bring you $80,000 a year to start?

Labels: geologists, oil

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

On one of my field trips last week, I collected this cobble of sandstone (penny for scale):

And here's the other side:

There's a delicate but telling geopetal indicator here in this sandstone: it shows us which way these sandstone layers were oriented in space when they were deposited as loose sand. Geopetal indicators give us "paleo-up," sometimes called the "younging direction." Classic examples include graded bedding, cross-bedding, and mudcracks. Here, it's a bit more subtle: small erosional "divots" in the layers of sand. These "divots" may be caused by something pushing down into the sand (the trace of an organism's trail), or may be caused by small amounts of scouring erosion. We only get to see them in two dimensions, so it's unknown whether they are simple pinpoints in three dimensions, or linear features -- perhaps even branching linear features. Reviewing the cobble's many layers, I've found three types of "divots":

Type 1 is a simple deflection of the the dark layers. It is more likely that the layer is deflected downward, but there is no guarantee: it could be a little lump of sand poking up from the bottom, too. In other words, Type 1 is not a completely compelling clue for paleo-up. Type 2 is more convincing as a geopetal indicator: here a lower layer or two has been actively scoured, and then an upper layer is draped over the scoured-out hole. Type 3 can also be seen though, and it's a weird one: I'm having a hard time coming up with a reason why two successive beds would both have a "divot" in the same location. Is this a squishing downward effect? For instance, were I to go stand on my bed, my weight would push downward on my comforter, but also the sheets underneath. They would both deflect from the bed's horizontal surface in the same downward direction. (Would this be a "duvet divot?")

See if you can find examples of all three in the photos above.

Labels: coastal plain, primary structures, sediment

A year or so ago, I picked up this nice sample of limestone in the Shenandoah Valley of Virginia (easternmost valley of the Valley and Ridge physiographic province). It was a cobble in a stream, not in situ, but it can't have come very far (by natural means anyhow) since it's quite angular. I liked it because of the alternating colors of its layers. I was not totally sure why they are different colors, but I strongly suspected it had something to do with different reactions to weathering (perhaps different calcite / aragonite ratios, or an increased silica / clay content in some layers?). I also liked the patterns of sedimentary layering, thinking back to undergraduate discussions of Flaser bedding and the like, but not remembering the details clear enough to interpret this one. Perhaps one of the sedimentary geologists can help clue me in? Still, I suspected it had something to teach me, so I brought it back to my lab at NOVA. Side view:

There, I sawed it in half. Top view:

To my chagrin, but not my surprise, the interior showed the layering less clearly. In the sawn section, I could clearly see where the weathering "front" had penetrated a short distance into the rock along the lighter-colored layers. While they were yellow-tan on the face of the sample, they were merely light gray in the interior. I decided to try and create a little weathering of my own, and reached for one of the students' acid bottles. I dropped about ten drops of acid on the sawn face, let it fizz for a bit, rinsed it off, and repeated the acid application. Almost instantly, the different layers jumped out into high contrast. The light-colored one was much more reactive than the dark colored one. Here's a view from the scanner which offers a comparison between the un-acid-treated sample (left) and the one I gave the brief acid bath to (right):

Not only does the layering jump out at you, you can see some micro-faulting too. Here's another view, from the camera, of the two samples, one stacked atop the other. I'm astonished at how 30 seconds of acid produced such a remarkable difference in their appearances:

As soon as I had documented the efficacy of the technique, I treated the second sample the same way as the first. One is now in the NOVA teaching collection, and the other is a proud new member of the CB office deskcrop collection.

Labels: limestone, nova, teaching, valley and ridge

About a year ago, I watched "The Blob" (the original 1958 version) via Netflix. As you're probably aware, it deals with an alien lifeform coming to Earth, a little blob of goo that assimilates human beings into its body and grows, eventually getting large enough to engulf a diner where Steve McQueen is hiding. My favorite moment came at the end of The Blob, when they discover that the blob doesn't like cold. So they spray it with CO2 fire extinguishers & freeze it. Then the Air Force comes in and air-lifts it up to "the Arctic." The police chief character says to Steve McQueen: "At least we've got it stopped." And McQueen replies, I kid you not: "As long as the Arctic stays cold." Oh, Steve, if only you knew! Looks like we've got one more hazard that climate change is going to unleash...

Labels: climate change, global warming, movies

Last week on one of the many field excursions, I found a nice cobble of amygdular basalt. Amygdules are vesicles (bubbles in degassing lava that didn't get the chance to pop before the lava solidified into igneous rock) that have been filled in with mineral deposits. In the mid-Atlantic, most amygdules are found in the Neoproterozoic lava flows of the Catoctin Formation, from which my cobble was presumably derived. The amygdules are typically filled in with zeolites, quartz, and jasper. This one doesn't show any jasper, but the basalt still appears to be basalt, too -- whereas the Catoctin typically is metamorphosed to greenstone / greenschist. I've noticed an association between jaspery amygdules and epidote formation in the metaingeous rock.

As with Skolithos-bearing Antietam Formation quartzite cobbles, clasts of the Catoctin deposited in the river gravels atop the Piedmont/Coastal Plain unconformity indicate a Blue Ridge provenance for the cobbles, and therefore a eastward-flowing river to deposit them 100 million years ago.

I took the cobble back to the lab and sliced it open on the rock saw. The brown circle in the background is a penny for scale.

Here's what the sawn surfaces look like after I sanded them down a bit and then scanned them:

Right purty, ain't it?

Labels: basalt, blue ridge, coastal plain, primary structures, sediment, virginia

Being outside with my students last week was great. Now that the weather is warming up, I'm looking forward to the start of "field trip season," which for me starts next week. This photo (by a friend of a friend) summarizes my attitude towards field trips:

My translation: "Field trips! Cue the singing angels! It's great to be outside! It's great to be a geologist! It's great to live on planet Earth! Love it, people: Play on your planet! Get out there and experience the one & only planet that you will ever know!"

Labels: field trips

I've already introduced you to two of my Honors students' field projects. Now for the last of the three -- Jason's project on the strained metaconglomerate of Klingle Road. Klingle Road is a "road" in D.C. that was damaged by a storm some years back, and never repaired. Some people have started using it as a park, while others clamor for the road to be fixed. Geologically, it's interesting because it exposes a rock unlike any other nearby: a distinctly foliated metaconglomerate. Because I am so clever, I call it the Klingle Road Metaconglomerate. It's part of the "Laurel Formation," which is one of many flavors of metagraywacke / accretionary wedge complex that make up the bulk of the Piedmont in this area. Here's some of the squished clasts that Jason is interested in:

We know these rocks got heated up a fair bit. How do we know this? Well, they flowed out into elongated shapes all oriented in the same direction for one (see the additional photos here). The outcrop is peppered with clusters of little plus-shaped protuberances: they are clusters of sericite (cryptocrystalline muscovite) in the shape of staurolite porphyroblasts. Staurolite is a reasonably high grade metamorphic mineral, and when we see the three-dimensional shape of staurolite, but it's been turned into relatively-low-grade sericite, it's an indication of "retrograde metamorphism." Basically, after hitting the peak of its particular metamorphic conditions (high temperature and pressure, growing staurolite), the rock is readjusting to lower temperatures and pressures, and those staurolite crystals are reacting to a mineral that's more stable at those lower temperatures and pressures: sericite.

But anyhow -- back to the metaconglomerate. It's made of clasts, and those clasts have been stretched. The question is: how much have they been stretched. Sometimes when strain estimates are made, we assume an initial sphere shape, and then measure the lengths of the various axes of the resulting ellipsoidal shape (the "strain ellipsoid"). But is the assumption of initial sphericity valid? Jason is testing this issue by measuring the axes of cobbles and pebbles from the metaconglomerate as well as loose cobbles and pebbles found in nearby Rock Creek. We want to get a sense of how ellipsoidal cobbles are before they experience orogenic shortening/stretching. Here's a shot of Jason, Spencer, and Victoria measuring cobble axis lengths on a gravel bar near the National Zoo:

And a shot of the crew close-up:

And, just for fun, here's one more shot from Victoria's field area on Broad Branch. We hiked up to the contact with the Kensington Tonalite (a ~464 Ma felsic intrusive rock -- essentially a granite) and found a series of small waterfalls over this resistant rock unit. In the sequence of cascades were a series of deep pools. I submerged myself in one of them:

Labels: appalachians, dc, field trips, nova, piedmont, sediment, structure, teaching

Lastly, in this final picture, you can see (on the left and in the foreground) what a lot of the large bodies of migmatite looks like: mostly granite with wisps of mafic residue strung out as thoroughly-foliated xenoliths. Their common alignment is oriented in the same direction as regional foliation. This granite yields U/Pb ages of ~460 Ma, which is Taconian in age.

Labels: appalachians, migmatite, piedmont, virginia

Last Friday, I had a fun local field trip, in search of ultramafic rocks included in the Piedmont's metamorphosed accretionary wedge complex. My companions on the trip were David and John, both of whom are retired gentlemen pursuing geology as a hobby. Because they're doing geology for fun, they are among the most dedicated and interested students I've met at NOVA. Friday's trip was something I've been meaning to do for a while, and both of them thought it sounded like an eye-opener, so they came along too.

Our goal was to find some new outcrops that we hadn't seen before. Of primary interest were several mafic and ultramafic bodies included in the larger metasedimentary complex of rocks that we know today as the Piedmont. As I've mentioned before, these Piedmont rocks are interpreted as being the rocks of an ancient (Neoproterozoic - Paleozoic) ocean basin. When the ocean basin closed during Appalachian mountain-building, the sediments of the ocean got squished and squeezed between North America and Africa. Mixed in with them were chunks of the ancient Iapetus Ocean crust, which would probably be recognizable as ophiolites if it weren't for that pesky regional metamorphism they endured as a result of the collision. Up and down the east coast, there are outcrops of these mafics and ultramafics along the presumed "suture" zone between ancestral North America and terranes (blocks of crust) that were once a volcanic island arc in the Iapetus Ocean. As with most geology field trips, we also found some other stuff worth noting, even though it wasn't our primary objective.

Our first stop (located thanks to Diecchio & Gottfried (2004) in USGS Circular 1264) was in Clifton, Virginia, where we went to see the unconformity between the Piedmont metamorphic rocks and the Triassic sedimentary rocks which overlie them in an ancient rift valley called the Culpeper Basin. Tragically, instead of a beautiful outcrop, we found freshly graded surfaces and several new McMansions. There was only a small strip of undeveloped land, about 20 feet wide and 50 feet long which had any rock left. But in that area, we found an outcrop of soapstone. Here, John scratches the soapstone (talc) with his fingernail. It's soft!

In this case, the soapstone is interpreted as being metamorphosed ultramafic rock. Close to it, we found this piece of conglomerate:

The conglomerate is the base of the sedimentary sequence in the Culpeper Basin: it's the Reston Member of the Manassas Sandstone Formation. Notice that it contains clasts of foliated metamorphic rocks -- these were derived from the older Piedmont rocks it unconformably overlies. The Piedmont rocks got metamorphosed during Appalachian mountain-building, and then when Pangea broke up, the Culpeper Basin (one of the Newark Supergroup basins) opened up and got filled in. The source for the infilling sediment was the neighboring area, not surprisingly including pieces of the Piedmont. Up-sequence, the conglomerate is overlain by the regular Manassas Sandstone, which is a rich brick red in color (classic Triassic red beds), and contains a wealth of primary sedimentary structures. I found this one piece, which unfortunately broke into chunks when I picked it up:

It displays ripple marks, raindrop impressions, and a few horizontal branching trace fossils. Anyhow, that was about it for the Clifton stop. We were bummed about the development destroying the outcrop. On to the next location, Indian Run, on the east side of Annandale. There, using the geologic map that accompanied Drake & Lyttle (1981), we walked along the creek bed looking for exposures of rock. We didn't have to go far before seeing some heavily-rusted green rocks:

The above photo is dominantly chlorite, but check this out:

Pyroxene-rich inclusions (xenoliths? olistoliths?) were observable in the heavily-weathered exposures. The outcrops here were saprolitic, meaning they were essentially "rotten rock." David was struck by how soft they were. He said "It feels like velvet!" We turned our attention to the more coherent specimens which were weathered out and deposited as cobbles in the streambed. I got a watermelon-sized specimen that's about 40% massive peridotite and 60% greenschist. (I showcased this leprechaun-colored specimen last night in Historical Geology lecture, when we were discussing the Taconian Orogeny.) We also found intriguing hints of mountain-building in clasts like this:

That's a couple of beautiful folds in gneissic metamorphic foliation. As above, the bright green minerals are chlorite. We also found some cobbles of sedimentary rocks mixed in with the locally-derived metamorphic rocks. For instance, here's a nice semispherical cobble of flint, likely derived from the flint-bearing limestones of the Shenandoah Valley:

How did this flint nodule travel ~50 miles from its source area to its current resting place in Indian Run? Likely, it was transported by an ancestral version of the Potomac River, which brought many westward-derived cobbles eastward during the Cretaceous. About 100 million years ago, this river deposited a layer of cobbles all over our local area, preserved today as the Potomac Formation. It unconformably overlies the Piedmont rocks, and can be found today as the basal layer of the Coastal Plain. It's even found as a layer topping our highest local hills. The exposures in Indian Run actually offered a nice view of the unconformity surface, with foliated metamorphic rocks below, and unlithified Cretaceous gravel deposits on top:

Just to close out this post, I'll show a few other cobbles found in the streams. Here's a gneiss containing big, beautiful porphyroblasts of garnet:

And here's a Skolithos-bearing boulder of the Antietam Formation (quartz sandstone / quartzite), which I originally posted a few days ago, but is so gorgeous it should be shown again if I'm talking about boulders.

Finally, as a preview of tomorrow's post, I'll show a boulder which hints at the complex relationship between the foliated metamorphic rocks (gneisses) of the Piedmont and felsic igneous rocks (granites) which were derived from the partial melting of the gneiss. In other words, this is a boulder of migmatite: rock that has experienced partial melting. We'll explore this in more depth with some in situ photographs tomorrow.

Labels: appalachians, culpeper basin, field trips, geology, nova, piedmont, virginia

Yesterday I was working on some reading for my MSU MSSE class, when Lola called me over. It was a reading day for her too, and she had just opened the most recent National Geographic. "Check this out," she meowed. The magazine had put a one-page story about "designer" mice (genetically modified for research) right across from a cat litter ad, and both the cat and the mouse were looking inward (towards the magazine's fold or "gutter"). This made it appear like they were looking at one another. The advertised cat apparently had other things on its mind than hunting mice, but I thought the overall layout was too funny to be a coincidence. Lola, on the other hand, was disgusted, feeling that the whole composition was disgraceful to catkind.

It reminded me of a time last month when Lola was reading the previous issue of National Geographic. This time, she was intensely reading, sounding out the big words, concentrating hard. I looked over her shoulder and saw this:

As part of that issue's focus on animal intelligence, it was a small photo of a baboon teaching a cat to sit upright. The photographed cat didn't want to sit upright, but Lola thought it was a great idea. For the next several days, she sat upright constantly, reading the New Yorker and Wine Spectator, puffing her meerschaum pipe and looking contemplative. But then she lost interest in sitting upright when she read about fossil ammonites. Admiring their graceful sprials, she promptly curled up into a ball. Immediately, she began purring. "It's much more comforable," she told me. "Ammonites must be smarter than baboons."

I pointed out her lack of exoskeleton. "Ammonites have shells, Lola," I said, admittedly a bit condescendingly. An hour later, I found she had taken over my office wastebasket:

Labels: humor, lola

Picking up with my series of posts introducing the work my Honors students are doing this semester: today we'll take a look at Spencer's project, which involves field work on a bedrock terrace (strath) of the Potomac River near Chain Bridge (which can be seen in the background of this photo). As before, ignore the datestamp in the lower-right of the photo. These pictures were taken last week, not in 2004.

This is in the westernmost corner of DC's "diamond" shape. The bridge leads across the river into Arlington, Virginia. As you can see, there's a lot of rock exposure here -- the sort of thing we go crazy over here in the east. As noted before, this is metagraywacke (sometimes metamorphosed to schist, sometimes to gneiss, sometimes just strongly foliated, and sometimes so lightly metamorphosed / deformed that it even preserves original sedimentary structures like graded bedding. The interesting thing about the Chain Bridge locality is that in amongst the metagraywacke are big chunks of other rock types. I'll refer to these as "clasts." Some geologists have interpreted them as sedimentary deposits; others as "olistoliths" (tectonically emplaced chunks in an accretionary wedge complex). Spencer is in charge of documenting the variety of these clasts, in hopes that it may tell us something about their ultimate source. Here's a big elongate clast of gneiss:

We had a good little field routine going: Victoria and Jason would go scout out clasts, and then mark their location with a chalk arrow. Then Spencer would document each clast's lithology and characteristics (e.g. foliation at an angle to regional foliation) and then photograph it. Once he'd photograph it, he "checked it off" with chalk. All of this chalk graffitti gets washed away with the next big rainstorm.

Some of the clasts are no longer in their original condition. The one below, for instance, bears a multitude of garnets, metamorphic minerals which reflect how the clast's original composition reacted to the higher temperatures and pressures of Appalachian mountain-building.

Another thing we saw a lot of in the Chain Bridge locality is erosional features related to the incision of the Potomac River into bedrock. Here's Jason showing off a pothole that drilled all the way through one outcrop:

Next time, we'll take a look at Jason's project.

Labels: dc, field trips, geology, nova, sediment, teaching

Here's a view in the creek bed of Spencer and Victoria looking for kink band outcrops. (Ignore the date stamp in the lower right: it is not accurate.)

A nice kink band. Width of photograph is ~25 cm.

Victoria takes the strike of the metagraywacke's foliation:

Here's a Z-fold in the foliation -- more of a kink "knot" than a kink band. The kinematic sense of motion in this photo is top-to-the-right (right-lateral):

Here, Jason and Spencer measure the orientation of a kink band:

A nice little outcrop of crenulation cleavage, showing porphyroblasts of chlorite (green/blue) and garnet (red/brown). The pencil is parallel to crenulation "wrinkles".

Next time, we'll take a look at the projects that Spencer and Jason are working on.

Labels: field trips, geology, nova, sediment, structure, teaching

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

What would it look like if Napolean Dynamite designed a website to promote energy conservation by switching out lightbulbs? Maybe something like the "Unscrew America" website. The navigation is a bit of a head-spinner, though. Take your Dramamine before you start moving that mouse around.

Labels: environmental, websites

A fresh location for the new round of A.W.o.G.E. This time we're visiting a syncline that was exposed in a roadcut about 20 years ago. I've blocked out the data source, since that could help narrow the search, and I'd also like to point out that I should have put an "s" on "geologist" in the lowermost annotation. Oops.

In the comments section below, be the first to name the mountain the roadcut goes through, and you will win a "GEOLOGY ROCKS" bumper sticker.

Labels: contest, google

It's almost cherry blossom season, so that means it's also time for the annual DC Environmental Film Festival. For two weeks, lots of interesting films are hosted by dozens of libraries, theaters, embassies, NGOs, and the like. Many of them are free. If you live in the DC area, this is an excellent opportunity to see some movies that you won't otherwise get access to. Even if you're not in the Capitol area, you can check out some of these films: this year, several of the films (like tonight's snow leopard movie) are available for watching free via the Internet. Enjoy!

Labels: dc, environmental, movies

Over the first half of the semester, I've been reading Vaclav Smil's comprehensive book The Earth's Biosphere. It's an incredible work of scholarship, and I recommend it to anyone with a solid foundational understanding of both biology and geology who's ready for "the big picture": an overall review which will give contextual perspective on each of the details of how the living portion of our planet works. It's a remarkable book, really. It covers so much, in such a precise, well-written manner, that it makes my head spin. It has forty pages of references (in small type)! As an example of the multidisciplinary nature of the book, I offer the following graphic from page 134:

In one image, Smil integrates information about seven variables: clay varieties, latitude, biome type, depth of weathering in the crust, precipitation, temperature, and evaporation! That's an incredible accompishment graphically, but he does the same thing in just about every sentence.

I read the book originally because a potential student recommended it as providing a "balanced" look at climate change. Curious to see what that meant, I checked it out of the library here on campus, and read it. It has an excellent and comprehensive scientific discussion of climate change, with a particular focus on how the Earth's biosphere will effect it, and be effected by it.

I feel obliged to give an example of something I learned, so here's amazing fact #3546 from the book: photosynthesis is really inefficient! Plants vary in how photosynthetically efficient they are, but the values range from plants that capture 0.1% of incoming solar radiation to the really efficient ones, which max out at capturing about 2% of incoming solar radiation. That's so not efficient! I had no idea.

Of course, no book is perfect, and I'll offer two complaints about The Earth's Biosphere: (1) A general theme is woven throughout the book of examining the work of neglected Russian scientist Vladimir Vernadsky, who made critical advances to our understanding of the biosphere, but hasn't gotten enough credit. Smil goes overboard in giving Vernadsky his due: it's Vernadsky this, Vernadsky that, every couple of pages through the whole book. I got sick of reading about him, and wished Smil could stick to the (excellent, fascinating) science, divorced from the persons who wrought it. (2) Every now and again, he threw in a superflous graphic, like this one:

Is the fish really supposed to be ~16 m tall? What's the point of this graphic anyhow? To show that fish live below the ice? Seems to me you could just say so. (Plus, the graphic needs the scientific name italicized, as in the caption.) I don't mean to snipe -- most of the book is super, but stuff like this irritates me. A fly in the ointment, I guess. The book's worth reading regardless.

Labels: books, climate change, global warming

DC Metro area residents, you're hereby invited to join me (NOVA) or Phil Justus (NRC) or Michelle Arsenault (NSF) on a geology hike along the Billy Goat Trail, a popular and rugged hiking trail upstream from DC on the Potomac River, downstream from Great Falls. Michelle and Phil and I take turns leading this excellent hike. You'll learn about the Iapetus Ocean, Appalachian mountain-building, and the incision history of the Potomac River. You'll see potholes, amphibolites, metagraywacke, migmatite, and the mysteriously-straight Mather Gorge. The Park Service has just posted the spring schedule online here. Reserve your space today!

Labels: appalachians, dc, geologists, piedmont

The New York Times reviewed a new book about birdwatching this weekend. If you can agree with the statement, "I can't think of any activity that more fully captures what it means to be human in the modern world than watching birds," then you might enjoy Jonathan Rosen's The Life of the Skies. The review (by Robert Sullivan, who wrote the book Rats, which has the best cover of any book ever) is astonishingly well-connected (in the Internet sense of the word): it weaves in allusions to Robert Frost, Jack Kerouac, and Theodore Roosevelt. I haven't read The Life of Skies yet, but it is now on my list.

I love running into birds. The other morning, when it was relatively warm, Casey and I went for a walk in the Zoo, and saw a pair of red-shouldered hawks (wild, not caged) building a nest in one of the big old orthern red oak trees there. It was cool to see: they were collecting sticks several feet long and doing short fly-hops through the canopy as they maneuvered into their nest site. Today, we went back and looked for them again, but there weren't there. Maybe out hunting?

In DC, the winter weather persists. It was cold and windy this weekend, and daylight savings time didn't help much. Soon, (very soon, I hope), the weather will warm and the birds will return. Right now, there's nothing to look at except rocks, cold rocks. Some of my Honors students and I got out in the field today to do measurements for their various projects, and when the sun was out, it was pretty nice. Still fleece and jeans weather, but you can sense spring is on the way.

Labels: birdies, books, nova, teaching

Later this spring, I'm teaching a geology course for a "Natural History Field Studies" certificate program offered by the USDA Graduate School and the Audubon Society. A friend informed me today that the course listing is online. NOVA's a better deal for students (and professors, frankly!), but I'm hoping to tap into a new population of students this way. Our field trips will be to (1) Shenandoah National Park, (2) the Shenandoah Valley and Massanutten Mountain, and (3) the Billy Goat Trail. As such, these NFHS students will get a nice cross-section of Appalachian geology, as recorded in three separate physiographic provinces (Blue Ridge, Valley and Ridge, and Piedmont, respectively). Just thought I'd mention it.

Labels: geology, nova, teaching

Juliet Eilperin reports in today's issue of the The Washington Post about the Ken Caldeira study I mentioned a few days ago. She also mentions another recent modeling study by Andreas Schmittner, who wrote (with others) a February 14 article in Global Biogeochemical Cycles that suggests that if global emissions continue on a "business as usual" path for the rest of the century, the Earth will warm by 7.2 degrees Fahrenheit by 2100. Schmittner's study continues: If we don't get to zero emissions until 2300, the temperature rise at that point would be more than 15 degrees Fahrenheit. (FYI: I haven't yet read the Schmittner, et al., study myself.)

Anyhow, the Post article reminds me of something I've been mulling over, and meaning to post since then.

I view climate change from two main perspectives: (1) as an earth scientist, and (2) as a citizen. As a scientist, I find it fascinating to watch how all this plays out. As a scientist, it presents an opportunity for learning, for greater understanding of how the Earth works. You see, geologists are limited scientifically: we often don't have the option of running controlled experiments on our topics of study: continents are too big, the spans of time are too vast. But with global warming, we have a colossal experiment that's being run, even though no one intended it as such. I offered this quote back in January, and I think I'll put it up again to give some context to my "scientist views climate change" perspective:

• "Human beings are now carrying out a large scale geophysical experiment of a kind that could not have happened in the past nor be reproduced in the future. Within a few centuries, we are returning to the atmosphere and oceans the concentrated organic carbon stored in sedimentary rocks over hundreds of millions of years."

-- Roger Revelle and Hans Seuss, 1957

In other words: The timescale of carbon storage is ~7 orders of magnitude larger than the timescale of carbon release. That's a large difference. Humans are thus changing the atmosphere's composition; but what effect will it have on the climate? Those who practice science can make some logical predictions based on our understanding of the natural world:

(A) It has been demonstrated for over a century that certain gases, like CO2, absorb energy in certain wavelengths of the electromagnetic spectrum. The gases that absorb in the infrared portion of the spectrum are the ones we call "greenhouse gases," since the majority of the energy re-radiated upwards from the Earth's surface is infrared, and absorption of this energy keeps the planet warmer than it would otherwise be.

(B) It has been demonstrated that in the presence of oxygen, biogenic carbon can be oxidized to release energy. Whether it's a campfire or gasoline (derived from petroleum derived from Paleozoic planktonic photosynthesis), organic carbon burns. When it does, carbon and oxygen combine, and CO2 is a product of the (exothermic) reaction.

(C) At numerous locations around the world, we have measured precisely the rising concentration of CO2 in our atmosphere. We have even measured precisely a corresponding decline in free atmospheric oxygen, as oxygen is consumed through the combustion of fossil carbon.

(D) These facts predict that the Earth's temperature will rise on average as a result of the greater concentration of greenhouse gases. That too can be measured, with multiple thermometers in multiple locations over a long period of time. What we find is that on average the temperature is going up (it's risen 0.7 of a degree Celsius, or ~1.4 degrees Fahrenheit over the past century), as is logically predicted by (A), (B), and (C).

So, as a scientist, I think it's really interesting: Here you've got some knowns, and some unknowns, and a logical structure linking them. Hypotheses yield predictions, and those predictions are being tested. Wow, scientist-me thinks, it's fascinating to see how the Earth system works when you alter a variable like atmospheric CO2 concentration.

On the other hand, I'm not just a dispassionate observer watching this all play out on an experimental planet: I'm also a person who lives on that planet and will be subject to the consequences of the experiment. It's from that perspective, the "citizen" point-of-view, that global warming scares the hell out of me. The Earth's fate is not in question here: our planet has endured far greater fluctuations in the past (both warmer and colder). The issue is for those of us who live on the surface of the planet Earth (humans and other species): as conditions change, will we be able to adapt? I'm concerned that some of the consequences are potentially too large for ecosystems to maintain their coherency. I'm worried about the huge proportion of my fellow human citizens (of the Earth) who dwell on the low-elevation coastlines of the world. The Earth will endure quite a lot of temperature variation; but I'm not sure about the organisms on its surface (of which I am one).

Last week, one story in the news was about the opening of the "Doomsday" seed vault on Svalbard. I was struck by the scientific parallels between the seed vault story and global warming, yet how very differently people were treating it. Science suggests that biodiversity is declining, and is subject to numerous threats, and we humans depend on viable seeds for our survival as a species. So, we're taking action by making this vault to keep our seed stock safe. It's totally uncontroversial. You don't see any Seed Vault Skeptics publishing editorials or holding conferences. Yet with climate change, there is a substantial voice in public life suggesting that the science is flawed, and thus that no action is required. Obviously, there's a HUGE difference between the relatively simple matter of creating a seed bunker in the Arctic and retooling the world economy's energy source, but those are both matters of political action. The science underlying each issue is strong and compelling. Whether we choose to act on the conclusions of that science is another thing: do we take action only when it's easy? Or do we take action when the science suggests that, for our own benefit as a species, we must?

Perhaps this is the third perspective with which I view climate change: as a "social scientist" intrigued would how people sort out complex issues like this. Will we be able to pull if off, as a society? Maybe it's already too late.

Some quotes from the Post article:

• "People aren't reducing emissions at all, let alone debating whether 88 percent or 99 percent is sufficient. It's like you're starting off on a road trip from New York to California, and before you even start, you're arguing about where you're going to park at the end."

--Gavin Schmidt, NASA Goddard Institute for Space Studies

• "[Global warming] is a classic inter-generational debate, where the short-term benefits of emitting carbon accrue mainly to us and where the dangers of them are largely put off until future generations."

-- Steve Gardiner, University of Washington

• "Each unit of CO2 emissions must be viewed as leading to quantifiable and essentially permanent climate change on centennial timescales."

-- Damon Matthews, Concordia University

Labels: climate change, CO2, global warming, politics