Although Half Dome formed deep within the Earth, near-surface processes are responsible for the Dome’s familiar profile.
The steep vertical face of Half Dome formed from vertical cracks, called joints,that developed in response to tectonic stresses in the Earth’s crust.
The spherical side is a result of exfoliation, a weathering phenomenon in which thin, concentric sheets of rock spall off the exposed surface.
Both phenomena are the result of the uplift of the granite pluton, erosion of the overlying rock layers and the accompanying release of pressure as this overburden was removed.
Ice-age glaciers flowed down the valley, clearing away the weathered debris, but the glaciers themselves did not carve out Half Dome, they just accentuated what had already been given shape by weathering.
Photo: spheroidal surface developed on granite at Yosemite
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