This view of Landscape Arch was taken in the afternoon. Note the fracture line that is roughly parallel to the underside of the arch. Cracks like this form by exfoliation, the process of the peeling off of bedrock slabs or shells in a series of concentric layers. Arches in the massive sandstone of the Entrada Sandstone form from exfoliation ("the peeling off from bedrock of slabs" of stone "in a series of concentric layers" (Harris, Tuttle, and Tuttle, 2004, p. 81). This is in conjunction with other weathering and erosion processes including freezing and thawing, erosion during rare thunderstorm downpours, and wind abrasion and atmospheric exposure (Lohman, 1975). |