 Pillars and columns , such as Washington Column and Lost Arrow , are created by cross joints . Erosion acting on master joints is responsible for creating valleys and later canyons . The single most erosive force over the last few million years has been large alpine glaciers , which have 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 creating domes such as Half Dome and North Dome and inset arches like Royal Arches . 
