Spring [Field Trip] Fever

Here at ESRU we've been enjoying some unseasonably warm weather, even hitting the 80's last week. Although the cold nights have returned, this amuse-bouche of spring has sent my brain into desert field trip mode.

As a undergraduate, my first extended field trip was to the Colorado Plateau. The trip was at the end of my freshman year, we left TMLAC in early May, and spent the next two weeks all over the Plateau. As you might imagine this was a watershed moment in my professional life, although my geoscience experience at the time was limited to one introductory course, but by halfway through the trip (camping in the snow on the north rim of the Grand Canyon), I knew I was going to be a geologist. I've returned to the Colorado Plateau a few more times, including a family trip (my graduate present from my parents), and my honeymoon (belated, but incredible).

In graduate school I either TA'd or hung out on a Death Valley/Owens Valley/White Mountains spring field trip many times. Depending on the course and professor this trip would change specifics, but at its base always involved a week in the desert. The timing of this trip is really perfect. It was usually smack dab between two academic quarters, a time when you were definitely ready for a break. More importantly, the weather this time of year is amazing. If you are lucky, your trip will coincide with the brief but colorful bursts of wildflowers. The high elevations are still cool (cold even, you can find snow fields once you get over a few thousand feet), and the low elevations are not yet absurdly hot. Most of the campsites cool off enough at night to allow for comfortable sleeping, but once the sun rises you can get away with shorts and Tevas. Plus, you beat most of the crowds. Win-win-win.

The desert is one of the things I've missed most since moving out here. In truth the region around ESRU is beautiful and scenic, especially this time of year, don't get me wrong. But it is not the same. Thoughts of these trips have inspired me to post some of my random pictures from the deserts, a sort of virtual field trip.

To fully put myself into the desert, I suppose I could wake up early, make coffee, and fry a bagel in butter (seriously, try this, fry the cut side of the bagel, then add cheese and guacamole, and make into a sandwich.....most amazing breakfast ever.)

So the pics

The end of Monarch Canyon in the Funeral Mountains, looking west into Death Valley.

Racetrack playa, Death Valley National Park

Mono Craters, Owens Valley California

Wildflower preserve east of Arvin, CA, California Golden Poppies in the foreground

Picture taken by moonlight (long exposure) in Arches National Park. Thanks to my brother for suggesting the technique.

Standard issue picture of Delicate Arch, Arches National Park

View looking into Death Valley

Ripples in sand dunes in Death Valley

The Boundary Canyon Detachment Fault, Funeral Mountains, Death Valley National Park. View is looking north, fault is at a low angle (it has actually been overturned) right at the break in color.

Deskcrop #3 - Ventifacts

Today's deskcrop is a ventifact. A ventifact is a rock that has been abraded by the windblown particles: sandblasted if you will. They typically have a heavily grooved or polished surface. Large ventifacts can have the grooves aligned with the prevailing wind direction. Small ventifacts, like mine, appear to not remain stationary, and therefore can develop a "brainy" texture. Ventifacts are not all that common, reflecting the relatively small importance of wind erosion. Water (both solid and liquid) is far and away the most powerful erosive agent around; wind is much less significant. In order to see well developed ventifacts, it helps to look in places where the wind is absurdly strong, there are abundant loose and abrasive particles (i.e. sand), erosion from water is relatively minor, and you don't have to worry about plants or soil covering things up. My samples are from Ventifact Ridge, in Death Valley National Park. (legal note, these were collected by someone who had the proper permit to take a few chunks). The rock itself is a basalt, Pliocene in age I believe (but cannot confirm right now).


Besides general interest, ventifacts and other eolian-erosion related features are the best earth analogs we have for many of the images sent back from the different martian landers. Below are images taken by the Viking and Pathfinder landers thought to represent Martian ventifacts (from Greeley et al., 2002.) Greeley et al., is an interesting paper that compares images sent back from the Martian landers to eolian features in the Mojave Desert and in Iceland.


In addition to dry environments, ventifacts need time to form. I haven't found any references for the average amounts of time needed to create well-developed ventifacts, but I imagine it is strongly dependent upon wind speed, lithology, and the type of particulate matter being thrown through the air. References would of course be appreciated.

Greeley, R., Bridges, N.T., Kuzmin, R.O, and Laity, J.E., 2002, Terrestrial analogs to wind-related features at the Viking and Pathfinder landing sites on Mars. Journal of Geophysical Research, v. 107, n. E1, 10.1029/2000JE001481.

Red Rock Canyon State Park

Red Rock Canyon State Park, in southern California, is usually the first stop on the Death Valley field trip my graduate department used to run over spring break. I had the chance to TA this trip once, and went on the trip a few other times. These pictures are from the apring of 2006, the last time I went on the trip, and the last time I've been in the area.

The Red Rock area has some spectacular exposures of Miocene fluvial sandstones, eroded in many areas into badlands style topography. During the Miocene, basin and range style extension was active all throughout western North America, eventually creating the corrugated morphology we see today. As I mentioned in this post, as the crust was stretched apart, it was broken into upflited ranges and downdropped basins.

The ranges are beautifully exposed, from California to Utah. Many geologists have made their careers understanding the ranges. The basins though, are buried, and therefore much more difficult to study. There are a few places where the basins have been dissected or are otherwise well exposed, and Red Rock Canyon is one of them.

The pictures are various views of the area, showing the Ricardo Formation dipping to the west. The beds have variable dips, reflecting their deposition during basin formation. In the first picture, I am standing on one of the interbedded basalt flows. In the background of the image you can see a more gently dipping surface.




And a close-up of the actual rocks

The Ricardo Formation is famous for it's fossils. This page is dedicated to the paleontology of Red Rocks, and includes boatloads of images of some of the finds. And to finish, some scenery from near the Ricardo campground.

A Joshua Tree

And a student on his way back to camp.

From the shore of Lake Manly

These are images from what used to be the northern shore of Lake Manly, the Pleistocene lake that once occupied what is now Death Valley. Lake Manly was roughly 600 feet deep, and over 100 miles long. Pretty impressive. I took these pictures in the evening on a field trip, if you are ever in Death Valley, this is the time to see things in the main part of the park. Spend the afternoons in the mountains surrounding the valley, and save the central valley for beautiful and cool evenings like this. Like with all of my pictures, please contact me if you'd be interested in higher resolution copies.

The Racetrack, Death Valley, California

So, Many of you will recognize these. Well, when I say many of you, I mean me, who is the only person really reading this blog. But, just in case you stumbled across this page, and know the answer to my question......the Racetrack, in Death Valley, these immense rocks "mysteriously" move across one end of a playa. Allegedly, no one has ever seen these rocks move. They can be quite large, much heavier than even I, with my superhuman sterngth, could not move. I have seen other geologists present theories on how they move, and anyone who has walked on wet playa mud or been in Death Valley during heavy winds can imagine them being blown all over the place. My question is, are there other places in the world with the same "moving rocks?" Anyone? Thanks.