Gphy102 lecture 15 weathering and mass wasting: the physical or chemical alteration of rock, usually involving disintegration to smaller elements. Can all be happening on same material. Chemical weathering: causes the decomposition, decay or rotting of minerals, chemical changes occur, caused by internal disruptive forces. Eg reaction of mineral to water: hydrolysis. Causes chemical alteration, but expansion as well, which contributes to breakdown of rocks. Feldspar hydrolysis yields clay minerals and (bi)carbonates: oxidation. Occurs when minerals in rock react with oxygen. Opposite reaction is reduction" (removal of oxygen: hydrolysis and oxidation tend to soften rock, weakening it and promoting further weathering, particularly along fractures and cracks, acid action. Creation of weak acids when compounds such as co2 dissolve in h2o (carbonic acid) Eg when carbonic acid comes in contact with carbonate rocks such as limestone it reacts to produce calcium bicarbonate, which is water soluble and is removed in solution.