Wednesday, June 3, 2009

Where in the West: Death Valley

Death Valley Cian Dawson, a hydrogeologist who can be found on Twitter as @cbdawson, correctly identified the June WITW as Death Valley, the "hottest, driest, and lowest" of our National Parks. The photo was taken about eight to nine miles north of Furnace Creek, on Highway 190, at about -200 feet below sea level looking south toward the Owlshead Mountains in the far distance, with the distinctive shape of the Mormon Point turtleback visible to the left and in front of the Owlshead Mountains.
It was early May (the 2nd, to be exact), and MOH and I had come into Death Valley through Titus Canyon. We were on a several-day roadtrip, and having spent so much time stopping and looking at things on the Titus Canyon part of the road, we zoomed through Death Valley, heading south toward Baker as fast as we could. The first photo, above, was taken at 1:14 pm, from the mouth of Titus Canyon looking south.
Yellow flowers were highlighting some of the alluvial fans, so we stopped, at about 2:00 pm, under the semi-cloudy sky, so I could shoot a few photos.
There are fantastic alluvial fans everywhere in Death Valley - for example, here, here, and here.
These are the only type of flower we saw in Death Valley.

After passing through Furnace Creek without stopping, at 2:25 pm we finally got to a little hill where we could look south into Badwater Basin. Badwater is just this side of that first dark brown turtleback ridge on the left, the Badwater turtleback. The Mormon Point turtleback is the distinctive ridge behind that, and the Copper Canyon turtleback is tucked away between the two.

The Badwater turtleback with the Mormon Point turtleback behind it.
All three turtlebacks of the Black Mountains - the mountains on the east side of Death Valley - are described in this paper, which has geologic maps and photos.
Here, we've stopped at the Natural Bridge parking lot, and I've unwittingly taken a photo of part of the Badwater turtleback with Badwater Basin barely in the picture.
We made a rather fast hike up the canyon to Natural Bridge: a bridge in older alluvium. Overhead, the bridge is cracked in several places. I don't know the development history or age of these cracks, but I personally wouldn't spend a huge amount of time beneath the bridge, especially during or after a rainfall.
Walking back down the canyon, I took this obligatory photo of Telescope Peak across Death Valley in the Panamint Range (3:15 pm). Viewing Badwater from Telescope Peak is #46 on the Geologist's 100 Things list; I have only viewed the peak from the basin.
We hurried down the road, driving past the crowded and hot Badwater, then pulled over suddenly when coming to this great view of the fault at the edge of the Copper Canyon turtleback. [It's really kind of hard to hurry at 45 mph.] The upper plate or hangingwall rocks are reddish to tan, mostly Miocene to Pliocene alluvial fan sediments with some volcanic and intrusive rocks (Drewes, 1967; Holm et al, 1994 a,b). The lower plate or footwall rocks are greenish, consisting of "quartz-feldspar gneiss and marble with minor amounts of pelitic schist... intruded by a host of igneous rocks that date from the early to late Tertiary" (Miller and Pavlis, 2005).

A closer view of the Copper Canyon turtleback fault.
It was 3:50 pm when I took the turtleback photos; we made Baker by 6:00 pm, and then had dinner at the local Big Boy (which was called Bun Boy in the 1980's).

Some References:Drewes, H., 1959. Turtleback faults of Death Valley, California, a reinterpretation. Geological Society of America Bulletin 70, 1497–1508.

Holm, D.K., Fleck, R.J., Lux, D.R., 1994a. The Death Valley turtlebacks reinterpreted as Miocene–Pliocene folds of a major detachment surface. Journal of Geology 102, 718– 727.

Holm, D.K., Pavlis, T.L., Topping, D.J., 1994b. Black Mountains crustal section, Death Valley region, California: Geological investigations of an active margin. In: McGill, S.F., Ross, T.M. (Eds.), Geological Society of America, Cordilleran Section, Annual Meeting: Guidebook, pp. 31– 54.

Miller, M. B, and Pavlis, T. L., 2005, The Black Mountains turtlebacks: Rosetta stones of Death Valley tectonics: Earth-Science Reviews, v. 73, p. 115– 138.

Troxel, B. W., and Wright, L. A., 1987, Tertiary extensional features, Death Valley region, eastern California: in Hill, M. L., Ed., Centennial Field Guide, v. 1, Geol. Soc. Amer., Cordilleran Sec., p. 121-132 [a field trip I was on!].

More Info:Death Valley at Geotripper

Geologic Map of the Mormon Point turtleback, Map #6.
Geologic Map of the Badwater turtleback, Map #7 (same link as above).

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