Massive rocks like granite generally to not contain planes of weakness whereas layered sedimentary rocks have bedding planes that can be easily pulled apart and infiltrated by water. A rocks structure also affects its susceptibility to weathering. Water dissolves calcite more readily than it does feldspar, so calcite is considered to be more soluble than feldspar.ģ. Different minerals show different degrees of solubility in water in that some minerals dissolve much more readily than others. Mafic silicates like olivine and pyroxene tend to weather much faster than felsic minerals like quartz and feldspar.

Different minerals weather at different rates. The mineralogy and structure of a rock affects its susceptibility to weathering.Ģ. (b) Physical Weathering is when rocks are broken apart by mechanical processes such as rock fracturing, freezing and thawing, or breakage during transport by rivers or glaciers.įactors Which Control the Rates of Weatheringġ. Oxygen oxidizes minerals to alteration products whereas water can convert minerals to clays or dissolve minerals completely. (a) Chemical Weathering results from chemical reactions between minerals in rocks and external agents like air or water. Over time, that mountain or hill is gradually worn down. As weathered products are carried away, fresh rocks are exposed to further weathering. Erosion relies on transporting agents such as wind, rivers, ice, snow and downward movement of materials to carry weathered products away from the source area. After the physical breakup and chemical decay of exposed rocks by weathering, the loosened rock fragments and alterations products are carried away through the process of erosion.ģ. The process of weathering typically begins when the earths crust is uplifted by tectonic forces.

Weathering is a term which describes the general process by which rocks are broken down at the Earths surface into such things as sediments, clays, soils and substances that are dissolved in water.Ģ.

Ice wedging water falls diagram