Geography & History Notes | KCSE, NECTA, ZIMSEC & GCSE

Rocks are the accumulation of minerals in a solid state. However, rocks include substances like clay, sandstone, shells, and corals. Rocks that contain metallic compounds are called ores. The rocks of the crust are made up of eight main chemical elements; oxygen, silicon, iron, aluminum, calcium, potassium, sodium, and magnesium. The following are values of rock to man: Rocks are very important in the formation of soils that can be used for agricultural production.  Rocks are used for building purposes: some rocks such as limestone, sandstone, gravel, and sand are used for building houses, construction of roads, etc. Some rocks are used as sources of energy or fuel such as coal and petroleum (mineral oil). Limestone is widely used for cement manufacturing. In Tanzania, cement is produced at Tanga, Mbeya and Wazo Hill. Salt extraction: salt usually originates from rock accruing strata, for instance, in Tunisia and Morocco there are large deposits of salt. Manufacturing of chemicals:...

what is weathering in geography? WEATHERING refers to the process of weakening, breaking up, and disintegration of the rock that forms the surface of the ground and that lie exposed to the weather. The process results from forces of weather such as changes in temperature, frost action, and rain action. The following are the importance of weathering to human life. Weathering is the initial stage in the formation of soil. It breaks down the initial rock mass into smaller fragments thus preparing the rock material for the formation of the soil. The depth of the soil, therefore, depends on the extent to which rocks have been weathered. Weathering produces other natural resources such as clay which is used for making bricks. Clay is also used for pottery. Another natural resource found from weathering is bauxite which is aluminum ore used in the extraction of aluminum Another significance of weathering is that weathering weaken rocks making them easier for people to exploit for example by m...