Half Dome, Yosemite National Park, in detail
A detailed view of the vertical cliff face of Half Dome, the spectacular and distinctive exfoliation dome in Yosemite National Park.
Half Dome consists of a coarse-grained granite mass which forms part of the batholith of the Sierra Nevada mountain range. The rocks were formed deep underground in 'plutons' of molten magma during volcanic processes, then lifted to the surface by subsequent earth movements. The distinctively rounded profile of Half Dome is a result of scouring by glaciers during the Sherwin glacial period, around a million years ago. Weathering (notably freeze-thaw action) of the domed surface layers has caused them to break up into plates, creating one of the world's most notable exfoliation domes.
(One of a pair of images in this gallery. This is a high-resolution scan from a 35mm original in my pre-digital archive).