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The solid granite rocks of Yosemite Valley appear to have been there forever and look as if they will be there forever. Yet this photo holds clues to the amazing changes that have taken place in the geologic history of Yosemite Valley and clues to what will lead to the Valley’s eventual demise. The rounded domes are the way granitic rock breaks as pressure is released as it rises through the crust. Fractures seen in the granite expose weaknesses in the rock that can lead to boulders breaking off. Those boulders lie in the bottom of the valley.

Bridalveil Creek flows through a notch in the granite before plunging over a cliff as Bridalveil Falls. The creek has eroded a V-shaped valley for itself within the U-shaped valley that was once filled with a glacier. The falls plunge into another larger valley, Yosemite Valley, which also has a U-shape from the glacier that once flowed through it.

On the far left side of the photo is what’s left of a granite dome that split in half. What will be left when the other half of Half Dome is gone?


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