Eagle Peak, Yosemite National Park

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Hide... Half Dome looms nearly due east over the valley, and the square cross section of the valley is quite obvious (caused by burial of the lowest ~1500' of the glacial valley). Royal Arches is at the edge of the sunlit area, above that is North Dome and above that and across Tenaya Canyon is Clouds Rest. Lost Arrow is deep in the shadows to the left, while Yosemite Falls hides just out of view. To the right of Half Dome, the lower part of Liberty Cap is lit (it is above Nevada Falls, which is in view to the right but barely flowing at this time). The edge og Glacier Point is at the far right. On the skyline above and to the right of Liberty Cap is Mt. Clark, anchoring the Clark Range to the right. The Cathedral Range stretches from behind Half Dome above the forested area left of North Dome. Mt. Hoffman is at the left, with the Mt. Conness area on the Sierran crest visible in the distance right of Mt. Hoffman. 11 December 1990.

Geologically there are two main stories here: the formation of the granitic rocks, and the glacial history. From Half Dome to nearly the Sierran crest bedrock is the Tuolumne Intrusive Suite, one of the youngest and largest intrusive masses in the range at just over 80 million years old. Somewhat more chaotic and somewhat older intrusions are closer, near Yosemite Falls. The glacial history here combines the Merced Glacier, that came down from behind Half Dome, and the Tenaya Glacier, that overrode the divide with the Tuolumne drainage from the right. Together they met below Half Dome, grinding down far below the modern valley floor. Although an early geologist (J.D. Whitney) supposed Half Dome must represent the remaining half of a huge collapse that formed the valley, no evidence of such a fault was ever found and the dome (which is nearly as steep on its south side as its north) has been assumed to be a purely erosional feature ever since.