Decomposed granite of silica sand, silt particles, and clay. Different specific granite types have differing propensities to weather, and so differing likelihoods of producing decomposed granite. The parent granite material is a common type of igneous rock that is granular, with its grains large enough to be distinguished with the unaided eye (i.e., it is phaneritic in texture); it is composed of plagioclase feldspar, orthoclase feldspar, quartz, mica, and possibly other minerals. The chemical transformation of feldspar, one of the primary constituents of granite, into the clay mineral kaolin is one of the important weathering processes. The presence of clay allows water
Exfoliating granite a couple hundred feet thick, separates from the underlying granite along an expansion joint to form a shell. As this continues, several concentric shells may form to depths of feet or more. Concentric slabs/shells of rock begin to break loose, onion-like layers subparallel to the exterior called exfoliating, sheet jointing, or fractures. As the granite expands the outer, most shells become susceptible to weathering by water pressure, freeze/thaw cycles, and functioning vegetation is a process called physical weathering. The sheets of granite are large enough to shave off sharp edges on the granite’s surface creating a dome shape. The overall