WEATHERING AND SLOPES
Weathering transforms solid rock into smaller fragments. It is an important process because these fragments eventually form the soil on which we depend for agriculture and food supply. Other products of weathering provide valuable minerals such as bauxite (for aluminium) and kaolnite (or china clay’ for pottery).
Rocks disintegrate and decompose when they are exposed to the atmosphere. The rate of weathering depends upon both the climatic conditions and the nature of the rock. The process is slow, although in some places it occurs at a faster rate than in others. For example, in an English churchyard, 200 years old gravestones made from sandstone might be so weathered that the lettering in impossible to read. Yet, in Egypt, granite columns have lettering that has remained virtually unchanged for 2000 years or more.
Chemical pollutants in the air, from vehicle exhausts and from industry, speed up the process of weathering. Industrialized regions suffer from air pollution far more than less developed regions. This is one of the reasons why the rate of weathering is faster in England than in Egypt.