The second full day of our trip included an exploration of several significant sites east of Death Valley National Park, including a trilobite fossil locality near Emigrant Pass, a welded tuff exposure on the Charles Brown Highway (178) east of Shoshone, and sediments from the Plio-Pleistocene Lake Tecopa. We then traveled north and had our first look at the Death Valley graben from Dante's View at the top of the Black Mountains. Late in the day, we did an environmental geology exercise at Zabriskie Point, and looked for Paleozoic fossils east of the park as the sun set.
Sunrise from our campsite at the edge of the RV park at Tecopa Hot Springs.
Searching for the elusive Olenellus...
Success!
Tecopa Lake formed around 2 million years ago when a canyon to the south was blocked by faulting or landsliding. It persisted for more than a million years until the blockage was breached by erosion. In that time, hundreds of feet of sediments filled the Tecopa Valley, including volcanic ash from as far away as Yellowstone National Park!
The sediments contain unique structures, and fascinating fossils have been found near by. A wooly mammoth skeleton is now on display in Shoshone, a short distance down the road.
Our next stop was several miles east on the road to Pahrump, Nevada. One of the more famous roadcuts in California geology can be seen here. It exposes not only a spectacular example of the interior of a welded tuff, with a layer of remelted obsidian, but also a fault exposure that has been used in many basic geology texts.
Is it normal or reverse? Be careful, even a few textbook authors got this one wrong....
The ignimbrite (welded tuff) has been thought in the past to be a coal seam, an obsidian dike, and who knows what else?
The day continued as we headed west towards Death Valley. See the pictures here!