Back to granite on Cima Dome

March 17th, 2011

A granite exposure near Teutonia Peak on Cima Dome. Note our jackets and hands in pockets!

ZZYZX, CALIFORNIA–Our last stop of the rapidly-cooling day was on the huge Cima Dome east of Zzyzx in the Mojave National Preserve. The dome is so large (about 70 square miles) that it is impossible to detect when you are actually on it, but easily visible from miles away. It apparently is the eroded root of a granitic intrusion formed during subduction in the Jurassic to Cretaceous. The alkali granite exposed here is very similar to that of the Granite Mountains we saw yesterday.

Potassium feldspar crystals in the coarse alkali granite of Cima Dome.

The soil of Cima Dome is derived almost entirely from the underlying alkali granite.

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