Yosemite National Park (3)

The geology of the Sierra Nevadas, and it is in these mountains that the Yosemite Valley sits, is a huge block of the Earth’s crust that has broken free on the east along a fault system and been uplifted and tilted westward as a result of the Pacific tectonic plate subjecting under the North American tectonic plate.  This process which is still going on today.  

Unlike the Grand Canyon where all rocks were sedimentary deposits almost entirely sandstone and limestone with a few layers of volcanic ash.  Yosemite’s rocks are almost exclusively granite which is formed deep within  the Earth as molten rocks cooled very slowly.  This as a opposed to the basaltic rocks we saw in the deserts of Arizona and California which is form by molten rock rising quickly to the surface and cooling quickly.  

The uplift of this granite started about 25 million years ago.  As the world grew colder about 2 million years ago the Sierras began hosting glaciers and ice fields.  As these cooling events came and went the advancing a receding glaciers carved out this remarkable valley.  

Today we went out and looked at all this Geology.

Views of Yosemite Falls, the water fall we see from our window

Half Dome and the Cathedral.  

El Capitan, zoom in on the last picture; rock climbers, many take at least two days to get to the top.

Bridal Vail Falls and views down the Merced River.  (The river that is still forming the shape of the valley.

The People of the "Big Gaping Mouth" This is the mouth.