America Day 4 - Tuesday 8th October

On Tuesday we headed to Red Hill across the Mojave Desert, where we arrived at 10:45am. Here we looked at Late Pleistocene (0.1 to 0.01 million years ago) volcanic deposits south of the Red Hill Cinder Cone. The deposits were made of primitive (young) basaltic lavas, had a variety of minerals included in them, and their texture suggested that when they were forming, they were moved slowly, but cooled rapidly. The origin of their melt was most likely to have been from a thin section of crust where extension occurred. 

Red Hill Cinder Cone

We then headed around to the corner to Fossil Falls, which consisted of the same basaltic lava, but here it had been cut by water after the last glacial maximum 20 thousand years ago. The lakes in the surrounding area would have filled up with melt water and over spilled into the valleys where it was able to carve through the rocks. We also found some black obsidian, which has a glassy texture as it cooled very rapidly and would have been used to make spear heads and tools. We also saw some petrogliths, which is art that has been scratched into the rocks, most often shamans and animals. These would have been made from 1000BC to 1300AD.

Fossil Falls

Petrogliths

At 2:30pm we arrived at Alabama Hills and examined the Cretaceous (145 to 66 million years ago) granites which had been brought up from depth by extension, which can be shown by the fractures. The temperature of exhumation would have been at between 350 and 500^oC (this can be seen from deformation in certain types of minerals and not others).

Fractured Granites

We then headed over to the Lone Pine Bajada, which is home to the 1872 Fault Scarp that formed during an earthquake. Here we tried to determine its nature and look at its history to see how and when it formed, and if this could be related to the East California Shear Zone. As we continued to work here on the 9^th, I’ll explain our findings then. At 5:45pm we headed down to the Dow Villa Motel in Lone Pine, which is where we stayed for two nights.

Lone Pine Fault Scarp