This is the eastern side of the Spring Mountains, as seen from Cottonwood Valley, a little W-SW of Las Vegas, southern Nevada, USA.  Most of the rocks seen in this view are Mesozoic in age.  The reddish-colored, slope-forming unit at the base of the mountains is the Chinle Formation (Triassic).  The Chinle here is overlain by a thick, light brown-colored, cliff-forming unit of Navajo-equivalent quartzose sandstones (Jurassic).  These two units are in a lower thrust plate.  A major thrust fault occurs at the top of the brown, cliff-forming sandstone unit.  Above the fault, in the upper thrust plate, are dark-colored Paleozoic rocks.  The upper thrust plate moved eastward (from left to right in these pics) during the Sevier Orogeny (Cretaceous).




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