Chemical Weathering

ADRIANNA R. PETERS

814001312

GEOG 1231

5th November, 2014.

Describe the agents and processes involved in the chemical decomposition of rocks. Which of the processes identified is likely to be most effective in eroding a terrain composed mainly of limestone and why?

The decomposition of rocks by various chemical processes is called chemical weathering. It is one of the most important processes in the formation of soils. During chemical weathering, the mineral composition of the rock is altered. Primary minerals, the original silicate minerals of igneous rock, are converted into secondary minerals. As the surface area of the rock increases, chemical weathering becomes much more effective. Also, the mineral composition of the rock has an impact on the rate of weathering. Certain minerals can withstand the effects of chemical weathering better than others, for example, quartz responds much more slowly to chemical attack than olivine or pyroxene. Water is the dominant agent in the processes of chemical weathering. In this essay, the agents and processes involved in the chemical decomposition of rocks will be described and the process which is most effective in eroding a terrain mainly composed of limestone will be identified.

As mentioned before, water is the most important agent in chemical weathering. Water is usually introduced as rain. Rainwater, which is usually mildly acidic, enters through micro-openings and cleavages in the structure and when in contact with the minerals in the rock, a series of chemical reactions occur which disrupts the mineral’s orderly atomic arrangement. This in turn causes weathering to occur. Chemical weathering occurs via different processes such as; hydration, hydrolysis, oxidation, reduction, carbonation, complexation and solution.

Hydration is the combination of water molecules with a particular substance or mineral. This combination leads to a change in structure. Hydration occurs in arid environments...