Devotees of cosmetics, who may cherish their exfoliation scrubs designed to peel away a thin layer of skin, will understand intuitively what the word means to a geologist: the weathering of granite rocks in great sheets, instead of through grain-by-grain erosion. Stone Mountain in Georgia and Independence Rock in Wyoming are fine examples of exfoliation; the classic case may be Yosemite’s Half Dome.

Bill McKibben