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The features in Yosemite Valley are made of granitic rock emplaced as plutons miles deep during the late Cretaceous. Over time the Sierra Nevada was uplifted, exposing this rock to erosion at the surface.

The oldest of these granitic rocks, at 114 million years, occur along the Merced River Gorge west of the valley. The El Capitan pluton intruded the valley, forming most of the granitic rock that makes up much of the central part of the valley, including Cathedral Rocks, Three Brothers, and El Capitan. The youngest Yosemite Valley pluton is the 87-million-year-old Half Dome granodiorite, which makes up most of the rock at Glacier Point, the Royal Arches, and its namesake, Half Dome.
Half Dome from Washburn Point

For the last 30 million years, glaciers have periodically filled much of the valley. The most current glaciation, the Wisconsinian was not, however, the most severe. Ice ages previous to the Wisconsinian were colder and lasted longer. Their glaciers were huge and covered nearly all the landmarks around Yosemite Valley except Half Dome, Eagle Peak, Sentinel Dome, and the top of El Capitan. Wisconsinian glaciers, however, only reached Bridalveil Fall in the valley. The glaciers widened the valley, but much of its width is in fact due to previous stream erosion and mass wasting along vertical joints in the valley's walls.
After the retreat of many of these glaciers, a stand of Ancient Lake Yosemite developed. The valley floor owes its flatness to sediment deposited by these stands (the last glaciers in the valley were small and did not remove much old lake sediment). The last stand of Lake Yosemite was about 5.5 miles (8.9 km) long and was impounded by a terminal moraine near the base of El Capitan. It was later filled by sediment, becoming a swampy meadow.

The parallel Tenaya Canyon and Little Yosemite Canyon glaciers were, at their largest, 2,000 feet (600 m) deep where they flowed into the Yosemite Valley near the base of Half Dome. They also formed Cloud's Rest behind Half Dome as an arête.

Near Glacier Point there are 2,000 feet (600 m) of mostly glacial sediment with at least six separate sequences of Lake Yosemite sediments. Here, huge and highly erosive pre-Wisconsinian glaciers excavated the bedrock valley floor, and much smaller Wisconsinian glaciers deposited glacial debris.