structural:reformatting
Rocks and erosion

Almost all of the landforms are cut from the granitic rock of the Sierra Nevada Batholith (a batholith is a large mass of intrusive igneous rock that formed deep below the surface). About five percent of the park's landforms (mostly in its eastern margin near Mount Dana) are metamorphosed volcanic and sedimentary rocks. These roof pendants once formed the roof over the underlying granitic magma.

Erosion acting upon different types of uplift-generated joint and fracture systems is responsible for producing the valleys, canyons, domes, and other features. These joints and fracture systems do not move, and are therefore not faults. Spacing between joints is controlled by the amount of silica in the granite and granodiorite rocks; more silica tends to form a more resistant rock, resulting in larger spaces between joints and fractures.

Pillars and columns, such as Washington Column and Lost Arrow, are generated by cross joints. Erosion acting on master joints is responsible for shaping valleys and later canyons. The single most erosive force over the last few million years has been large alpine glaciers, which turned the previously V-shaped river-cut valleys into U-shaped glacial-cut canyons (such as Yosemite Valley and Hetch Hetchy Valley). Exfoliation (caused by the tendency of crystals in plutonic rocks to expand at the surface) acting on granitic rock with widely spaced joints is responsible for producing domes such as Half Dome and North Dome and inset arches like Royal Arches.