Here's a couple of more photos from my travels out west this summer. This is in Jackson Hole, the large valley that abuts the Teton Range immediately to the east. If you've never been to the Tetons, you must go and check them out for yourself. They are an awesome, singular mountain range in the United States. Their shapes and sheer relief remind me of the Karakoram, or Torres del Paine, or some other awesome mountainous region of the world. It's really jaw-dropping.

Here's a shot of the Tetons from the northeast, visually pairing them with a line of coniferous trees in the foreground. Photographically, I like this parallelism in their shapes:



So what's up with the Tetons? What geologic processes give rise to their readily-apparent awesomeness? There's two main things going on here: faulting and glaciation. First, there's a major normal fault along the base of the range. The Tetons have moved up as a block while the Jackson Hole basin has dropped down as a block. As the rocks of the Tetons (some as old as 2.8 Ga) have been eroded, sediment was generated, and that dropped down to fill in the hole to the east. Jackson Hole is full of of sediment (over 20,000 feet deep), and then the peaks of the Tetons rise an additional 7000 feet beyond that. Based on offset of the Cambrian Flathead Sandstone on either side of the fault, total displacement is estimated to be 30,000 to 35,000 feet (Love, 1987). Even relatively young geologic units in Jackson Hole, like the Yellowstone-erupted Huckleberry Ridge Tuff (2.1 Ma), dip significantly towards the fault (Good and Pierce, 1996). Movement along this fault is ongoing, raising the mountains on average ~1 centimeter per year, with most movement having taken place over the past 9 million years. The Tetons are generally regarded as the youngest range in the Rockies.

Here's a shot coming north from the Gros Ventre landslide area (subject of a future post) towards the main road. A photogenic herd of bison was grazing on the grassy sagebrush flats, purposely maneuvering between me and the mountains so they would have a nice backdrop:



Once the Pleistocene ice ages began, the tall Tetons accumulated a lot of snow, which packed into glacial ice. Alpine glaciers started flowing downhill, and carving the rock of the mountains as they did so. That created the distinct U-shaped valleys seen in these photos, and left pointy little nubbins between them: the glacial horns like the Grand Teton and Mount Owen. The rocky debris scraped off the Teton block was deposited in Jackson Hole along with till from the Yellowstone ice cap to the north. These piles of glacial till are easily demarcated by the coniferous trees that grow on them, unlike the grasses and sage of the outwash plain.

References:

Good, John M., and Kenneth L. Pierce (1996). Recent and Ongoing Geology of Grand Teton and Yellowstone National Parks, Grand Teton Natural History Association, Moose, Wyoming, 58 pages.

Love, J. David (1987). "Teton mountain front, Wyoming." In: Geological Society of America Centennial Field Guide - Rocky Mountain Section, Stanley S. Beus, ed. Geological Society of America, pp. 173-178.

Labels: faults, geology, glacial landforms, travel, wyoming

Just now getting around to reading last month's issue of National Geographic, but it's a good thing I got to it yesterday rather than tomorrow -- because today's the day I talk about comets, asteroids, and meteors in Physical Geology class, and one of the topics that people always love to talk about is what happens when those big dumb space chunks smack into Earth.



The article's a good read, and illustrated with magnificent images, like this classic 1972 image of a fireball over Jackson Lake, Wyoming. That's the Tetons in the background. Check it out.

Labels: meteors, news, wyoming

On Saturday, June 14, I drove from Fort Collins, Colorado northwest across Wyoming, ending up just west of Cody in Shoshone Canyon.

Here's a few photos I took along the way:

Hogbacks (or "incipient hogbacks?") north of the Interstate (not sure whether this qualifies as the Laramie Mountains or the Medicine Bow Range, or some other range altogether).

Regardless, what you're seeing here is what happens when tilted sedimentary strata are incised by streams. The stream valleys develop at regular intervals along the slope, and notch the sedimentary layers, which themselves have different resistances to erosion. As a result, these triangular-shaped slabs end up poking up along the flanks of the mountains (the Flatirons outside of Boulder, Colorado, are perhaps the best known example).

The Wind River Range appears in the distance. Seeing big bad mountains makes me happy.


Road trip man!


The Prius at the southern (upstream) end of Wind River Canyon, between Shoshoni and Thermopolis:


...And looking downstream (north):


Unconformity between Archean basement rocks and overlying Cambrian sandstone:


The Wind River:


An outcrop on the way north, somewhere south of Meeteetse. Got some cool green concretions here, and coasted downhill for more than ten miles:


Camp at the end of the day. This is at Buffalo Bill State Park, between Cody and the eastern entrance to Yellowstone (Sylvan Pass, subject of a photo I put up yesterday). The body of water seen here is the Shoshone Reservoir. I enjoyed a pleasant evening here of drinking wine, writing a letter, and watching grebes in the water.


Dark clouds came over later, hastening nightfall over the park. Note the addition of the rainfly to the tent. Turns out we just got a sprinkle, no real downpour.


Life on the road is (was) good. Months later, it makes me happy to look at these photos and think about rolling along across the great North American continent, checking stuff out, seeing new places. Classes start on Monday for me, and I'll be locked down in DC for a bit... a fair trade, it seems to me, if my job allows me to go out and see places like these during the summers.

Labels: birdies, travel, wyoming

...No kidding!

This photo was taken in early June, when I drove through Yellowstone for the first time this summer... there was still snow eight feet deep along Sylvan Pass at that time!

Labels: snow, travel, wyoming, yellowstone

This summer, I saw "the Great Unconformity" in a couple of locations.

An unconformity is a break in the local geologic record -- a period of time which elapsed without being recorded by the deposition of rock units. Often unconformities mark places where erosion has erased part of the local rock record, but sometimes they just mark periods of non-deposition. (Analogy: You can get a blank page in your diary two ways. You can either take a day off from writing, or you can write that day's entry and then later go back and erase it. Either way, you end up with a day going by and no journal entry.) People call the major break between metamorphic and igneous "basement" rocks and overlying sedimentary layers the "Great" Unconformity, though it's not the same age everywhere. It's just shorthand, really.

Anyhow, here it is in the Grand Canyon (photos provided below are both unadorned and annotated versions):





Give or take, there's about 1.2 billion years missing along this ancient erosional surface. Intuitively, this probably makes sense, since metamorphic rocks like schist and 'distilled' intrusive rocks like granite are characteristics of mountain belts, where they form at depth. In order to get those interior-mountain-belt rocks to the surface takes lots of erosion over lots of time (though not necessarily that long -- in DC, for instance, we have interior-mountain-belt rocks exposed that 'only' took 360 million years to make it to the surface). In the above photos, the metamorphic rocks and granites below the unconformity formed about 1.7 billion years ago, during the Mazatzal Orogeny, and the sedimentary layers on top (both quartz sandstones) were deposited in the Cambrian period, about 543-488 million years ago. They represent passive margin sedimentation along an ancient transgressive seashore, something like modern day beach sands along the east coast of North America. So, to get something like the Great Unconformity, take something like coastal Maine (Acadia National Park, say), and bury it beneath something like Virginia Beach.

And here "it" is again, in Wyoming's Wind River Canyon (between Thermopolis and Shoshoni):





A zoomed-in look at this same outcrop:





This time, however, the rocks below the unconformity are much older* metamorphics (schist & amphibolite) and granite. According to Maughan (1987), these are the oldest rocks exposed in Wyoming, having formed about 2.9 billion years ago. They were then metamorphosed at 2.75 billion years ago. These truely ancient rocks (Archean) were then eroded and exposed at the surface, where quartz-rich sand was laid down atop their burnished roots. Aside from the difference in the age of the underlying basement rocks, the story is very similar to the one at the Grand Canyon.

* Thanks very much to Kim, who pointed out my error in under-stating their age in an earlier, more-poorly-researched version of this post.

Reference:
Maughan, E.K. (1987) "Wind River Canyon, Wyoming." In: Geological Society of America Centennial Field Guide - Rocky Mountain Section. S.S. Buess, ed. p. 191196.

Labels: archean, cambrian, dc, grand canyon, primary structures, proterozoic, wyoming

Here's a quick recap of my cross-country journey, for those who are interested in such things.

I left Bozeman on Saturday morning, July 26, and drove east on the Interstate to Billings, then diverged southeast towards Little Bighorn. There, I verified a comment from a Lakota friend at MSU that with my new bushy mustache (see change in icon above), I look a wee big like George Armstrong Custer (Custer & his men were killed by Lakota and/or Cheyenne warriors). After a short picnic there, I kept driving across southeast Montana, and into northeast Wyoming. My goal for the night was Devils Tower, where I have positive memories from my "North by Northwesty" roadtrip two years ago. I got to Devils Tower in mid-afternoon, just in time for a wicked-looking thunderstorm to roll in. Pendulous looking mammatus clouds were hanging down, and the skies turned a darker grey than Lola. Rain and wind came through, and a big dead branch from one of the cottonwoods in the campground came crashing down, but not on anyone's car or tent. When the skies cleared up, I drove up to the visitor's center and took a walk around the tower. It's awesome: massive columns, some of them twenty feet across. The rock is a porphyritic phonolite, and it's quite pretty to look at: big feldspars (5mm) set in a fine-grained grey matrix. Lovely.

The next morning (Sunday), I headed for Red Bird, Wyoming (along Wyoming's eastern border), where Cruisin' the Fossil Freeway suggested there would be oodles of ammonites in concretions in the Pierre Shale, some a foot across. When I visited the Denver Museum of Nature and Science earlier this summer, Kirk Johnson reiterated to me that Red Bird was the place to go for ammonites. But once I got to where Red Bird should be (according to my road atlas), there were no highway signs indicating that the town existed. Worse, there were no outcrops, and no sign of public land. (And one thing that an amateur fossil collector does not want to do in Wyoming is trespass on a rancher's land.) So, no Red Bird ammonites for me. Oh well, no worries: I had collected ammonites from a tongue of the Pierre Shale (the Bearpaw Shale) earlier in the summer on BLM land near Glendive, Montana, and scored some good specimens there. I cruised south, stopping at the Sierra Trading Post outlet in Cheyenne, Wyoming, and dropping some cash on some new duds (STP is mainly a catalog business, famous ten years ago for their amazing deals, but the company seems to be shifting to more mainstream business nowadays, including multiple brick-and-mortar locations). Then another hour on the road brought me to Fort Collins, to the house of Larry Wiseman, where I stayed earlier in my trip. He and I got some pizza and 90-Shilling Ale (Odell's) and traded tales about our summers.


The next morning, we had coffee on Larry's front porch and watch the sun rise. I packed up and hit the road, heading for Kansas. In my rear-view mirror, the Rockies shrank and vanished from sight, a melancholy fade. Out into the plains... In mid-afternoon, I rolled into Oakley, Kansas, where I headed for the Fick Museum. The Fick Museum is interesting on multiple levels: it's got some stellar fossils from Kansas's Smoky Hill Chalk (member of the Niobrara Formation), like a Xiphactinus (massive fish) and a Tylosaurus skull (even more massive mosasaur). But it's also got some whacked-out art: the founder, Vi Fick, was into making art with local "art supplies," and so the walls show his portraits of eagles rendered entirely in rattlesnake tails (see image at right, from this online gallery), or his geometric arrangements of thousands of fossil shark teeth. There's even an oil painting Fick did of "God making the Cretaceous seas," which shows a bearded diety surrounded by flames (it kind of reminded me of Hindu art) making pleisiosaurs and pterosaurs. Not the usual way you see fossils displayed, or paleontology depicted!

At the Fick Museum, I met up with Ron Schott, doyen of the geoblogosphere, who graciously agreed to show me some cool Kansas geology. Ron and I headed south from Oakley towards Monument Rocks, an outcrop of the Smoky Hill Chalk. Ron was eager to gigapan the outcrop, and he set up the little device: essentially a robot that directs his camera to take high-resolution photos in a systematic grid. Pretty cool, really -- I guess I hadn't realized what a Gigapan really was before seeing it in action. I got to meet Ron's two little plastic elves that he uses for scale, and personally placed them on a ledge of chalk for the photograph. The grid of pictures eventually gets digitally stitched together by software, and available for sharing online.

From there, Ron and I headed back up to Oakley, stopping en route so I could collect a couple samples of the aquiferiferous Ogallala Formation, and then headed east, then south again, towards Castle Rock, another chalk outcrop. Here, we tested out my Prius' shocks on the dirt tracks, and checked out the largest cliff in Kansas (nearly getting blown off it by the intense wind), and then prospected for fossils below. I found some fish scales, and a shark tooth! Also inoceramid clam fragments, encrusted with oysters (apparently a common feature of the bottom of the Western Interior Seaway). No mosasaurs, though... Back to the road, and into Hays, Kansas, where Ron put me up in his guest room. We had dinner and a few beers at the Lb. Brewing Company, and thought about recording a PodClast, but then it slipped our minds. We discussed field trips, tenure, publications, and related topics. A good time! Thanks again to Ron for being such an excellent host.

The next two days (Tuesday and Wednesday) were essentially just driving. On Tuesday, I made it to Indianapolis, Indiana, and spent the night in a hotel there. On Wednesday, I turned north, and drove up into Michigan, and crossed into Ontario at Port Huron / Sarnia. Why go to Canada on my way from Montana to DC? Well, I'm teaching my Snowball Earth class this week at NOVA, and some of the rock samples I needed were stuck at Brock University in St. Catherines, Ontario. Usually they get shipped to educators who want to use them, but because of alleged border complications, I had to go get them myself; a five hundred mile detour! Fortunately, I have good friends who leave in Waterloo, Ontario, so I went and stayed with them. Mike and Natalie Leuty have been friends since 1996, and we had a good evening catching up. They have a sweet house in a suburb full of professorial types who teach at one of the several universities in town.

On Thursday morning, Mike and I had coffee on his front porch while his kids played in the yard, and then I packed up my kit and got rolling. I made it to Brock by 11am, and got the Snowball Suite. Because it's in a giant black case that looks suspiciously like a rifle case, I packed it under a pile of other gear in my car. At any rate, I crossed back into the United States without any static from customs officials, and rolled through Buffalo, New York (twice in one year!) I made my destination for the night Ithaca, New York, where I have a friend who's going to grad school at Cornell. I've never been to Ithaca, but I hear that it's "gorges" from many people. So I called my friend, Kathryn Werntz, and she was indeed around and accepting visitors, so I drove through the finger lakes region (five subparallel glacial troughs now filled with water), and found my way to her bungalow. Kathryn and I took a walk through Cornell's campus (two amazing gorges cutting through it), had some Indian food, and went to get dessert at Purity Ice Cream.

In the morning (Friday), I got up and we went to Gimme! Coffee for some caffeine. Thus fortified, I hit the road for my final day of driving. East to I-81, then south through Pennsylvania. At Harrisburg, I turned onto I-83, which took me to Baltimore, and from there it was a familiar zoom down the B-W Parkway into northeast DC. The dome of the Captiol was visible to my left, and then the comfortable sights of Florida Avenue and U Street. Up the hill, and a left on Harvard Street, and I was back in Adams-Morgan. Home! Finally!

Labels: appalachians, canada, chalk, colorado, field trips, glacial landforms, kansas, montana, national parks, new york, snowball earth, structure, travel, wyoming

A quick note here, just for the sake of completeness, on my final MSSE class of the summer: "Examining Life in Extreme Environments." This was a cool class, but structured in a different way from my other MSSE courses: it was set up more like a conference, with a variety of different speakers on different topics, interspersed with activities. The organizers, Susan Kelly and Monica Brelsford used a grant from NASA to help fund the course, which meant they had the money to fly speakers in from NASA Ames, the University of New Mexico, and the Wrigley Marine Science Center on Catalina Island, California. We also had a presentation piped in from Woods Hole. The goal of the class was to look at living organisms that manage to survive in 'extreme' environments, like really salty, really hot, really cold, really acidic, and so forth. Why study these bacteria and archaea? We're hoping they will give us insights into (a) the origins of life on Earth, and (b) the possibility of life on other planets or moons elsewhere in the universe. We had a field trip to Yellowstone National Park to look at microbial mats; we looked at cultures of hyperthermophiles; we listened to excellent talks by Mark Young (viruses as a source of genetic diversity), Ed Adams (new subzero lab tour), and Robert Szilagyi (thermodynamics of the origin of life). As you can see, it was pretty diverse -- all week long, always something new and interesting. I really enjoyed it!

Labels: archean, astronomy, cold, hot springs, montana, msse, wyoming, yellowstone

After I got off the river at the Grand Canyon, I drove to Moab, Utah, where I have a friend from my days working outdoor education in southern California. Pete and I went swimming in Mill Creek (water + slickrock = awesome plunge pools) and checked out the sunset from the top of a dome of the Navajo Sandstone north of town. We had dinner at the Moab Brewing Company, which was delicious. The next morning, I checked my e-mail and got an oil change, then went up to Arches National Park to pay homage to Edward Abbey by taking a hike to Delicate Arch. They even have a small exhibit in the visitor center about Cactus Ed -- a nice acknowledgment on the part of the park that his book Desert Solitaire piqued interest in the park for many people.

After my hike, I got back in the car, and headed north to the interstate, then east into Colorado. Past Grand Junction and Delta, to the little town of Montrose, where I got final supplies for a couple of days in Black Canyon of the Gunnison National Park. I pulled in relatively late in the day, so just settled into the campsite. It felt good to be camping at high elevation, with cool temperatures, again. The next day, however, July 4th, I spent in exploring the park. I was surprised to learn that there is no trail down to the bottom of the canyon from the rim, but they do let people descend via "the Gunnison Route," a steep-ass ditch full of loose scree and talus. It was pretty sketchy, and pretty exhausting: not much fun. I kept thinking "there has to be a better way to do this." The reward was at the bottom, where the Gunnison River runs cool and fast. The Gunnison has carved an incredible gorge here: steep, deep, and with a steep river profile. It's a classic case of steam superposition over a buried Laramide uplift. During the recent episode of uplift, the Gunnison cut down through overlying sedimentary strata (including the Entrada Formation's pink sandstone, visible on the north rim) and into the underlying Mazatzal-aged (~1.7 Ga) igneous and metamorphic complex. This resistant rock is what makes up most of the canyon. It looks a lot like the Grand Canyon's inner gorge, with pink ribbons of granite leaping through the amphibolite-grade metamorphics. Anyhow, the river was very refreshing. I rested there for a while, and ate some lunch (tortillas from nearby Olathe, Colorado, wrapped around mozzarella and turkey pepperoni.) The hike back up was a big slog, and about as enjoyable as the hike down ("There has to be a better way of doing this!") Up top, I drove the road along the south rim, admiring the various viewpoints into the chasm and taking small hikes.

The following morning, I packed up camp early, and drove all day. I went west back to Grand Junction, and took a cool little road (Route 139) north over Thompson Pass and through some cool BLM land, replete with pictographs. I got some GREAT gas mileage after Thompson Pass, basically crusing downhill at 100 m.p.g. for over an hour. Awesome! Then through Dinosaur, into Vernal, Utah, and then into Wyoming at Flaming Gorge.

At Rock Springs, Wyoming, I went north on 191, through Pinedale (nearby Fremont Lake is the type location for Pinedale Till, the Rocky Mountain version of the Wisconsin Glaciation), and up to Jackson. Man, Jackson's a tourist trap! Yikes! Not as bad as Vegas, but I definitely didn't linger with the sunburnt hordes there. I had a date with the Gros Ventre landslide. Just northeast of Kelly, Wyoming, this is a classic location in the study of mass wasting events. I camped on the lake created by the 1925 landslide, and spent the next morning photographing the scar and debris pile which dammed the Gros Ventre River. Unlike the Madison River's landslide and resulting "quake lake," no one was killed with the initial earth movement at Gros Ventre, but when the dam failed two years later, the resulting flood drowned six people in Kelly. I first learned about the Gros Ventre slide as an undergraduate, and I teach about it today, so it was a real pleasure to see it firsthand.

Next morning, a ho-hum commute through Grand Teton and Yellowstone National Parks and up into Bozeman.

Labels: colorado, montana, national parks, travel, utah, wyoming

Sooo.... I've been "delinquent" about posting (if five days off counts as delinquent). But the long and the short of it is that I made it to Bozeman, and started classes, and have settled into life up here. After leaving Denver, I spent a couple days in Fort Collins, Colorado, staying with my undergaduate mentor professor Larry Wiseman. When I was at William and Mary, I forged a strong relationship with Larry, and that persisted even though I defected from biology (he's a developmental biologist, and chair emeritus of the department there) to geology (basically because they had more field trips). Anyhow, he and I would gather once a month or so for coffee and talk about life, the West, Ed Abbey, art, and science.

Now he's retired and pursuing bird rock art and also teaching cell biology at Colorado State University (in Fort Collins). We drove up to Rocky Mountain National Park and toured the various microbreweries and restaurants of Fort Collins (and Lyons). It was, in short, a good time.

Departing there on Saturday morning, I drove north through Wyoming, and camped at the end of the day at Buffalo Bill State Park, on the east flank of Yellowstone. On Sunday morning, I drove through the park, marvelling at six-foot-deep snow on Washburn Pass, and cruising along past tourists and bison galore. I stopped once, to look at the single petrified tree there, and then rocked and rolled on up the Paradise Valley to Livingston, and thence westward on the interstate to Bozeman.

In Bozeman, I'm enrolled in the Master of Science in Science Education program at Montana State University. It's essentially all science educators who are taking graduate coursework to become better science educators. And it's fun! This week, I'm taking Dave Lageson's class on the geology of the northern Rocky Mountains. More on that later, perhaps, but the point for now is that I'm enjoying it, and enjoying interacting with my fellow MSSE educators.

Tonight, I had a bonus, when we had a mini-conference of geobloggers. I guess there's somewhere around 50 geobloggers out there now, but we had four of them sitting at one table in Montana Ale Works, talking rocks and fossils and blogging and whatnot. That's got to be a record for the geoblogosphere. It was a lot of fun. Thanks to Mel, Brian, and Jeannette for making it happen!

Labels: field trips, montana, msse, travel, wyoming, yellowstone

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