Five stages and three substages of weathering of rock material have been recognized in the granite from Hingston Down, east Cornwall, England. Changes involved in the seven stages have been characterized quantitatively by petrographic modal analysis of thin slices of the rock and determination of a micropetrographic index Ip. A second quantitative index is the microfracture index, Ift.
Mass weathering grades may be characterized in terms of petrological changes in granite materials comprising each grade, and may be quantified in terms of the various micro-petrographical indices.
- © The Geological Society, London 1978