Geological Agents

After a miner has obtained some understanding on how minerals and rocks are formed, he or she should then also learn about the crustal movements of the earth. The types of crustal movements of the earth include gradation, vulcanism, and tectonism.

Gradation has to do with the breaking down of surface rocks due to water, ice or air. This is broken down into two main subdivisions, which are degradation – a wearing down and aggradation – which is a building up by deposition.

In most cases these two effects are conferred combined under the terminology, weathering, because there is really not any way of separating them effectively. A lot of these forces continue to take place and the process has been occurring for millions of years now.

Physical weathering envelops the development when the rocks have been reduced into little fragments without having gone through a chemical composition change. 

One of the most important reasons of physical weathering is when there are formations of ice in cracks. These, under geological terms are more commonly known as glaciers and their actions are known as “ice”. Ice formations that take place on a yearly basis, are known as “frost” and this is a process of expansion. The action of frost is divided into two subdivisions, which are frost wedging – in which the ice forms depressions or pockets and makes use of a sideways force, and there is frost heaving that refers to the process when ice is formed in cavities under the earth and makes use of an upward pressure.

If you were to look at the fissures or crack and potholes you would be able to see wedging. One of the biggest effects of heaving is how it lifts the surfaces of roads during winter. Because of the expansion and contraction that takes place, rock little by little becomes disintegrated over a period of years.

Even in cases where the rock does not have a porous area to take in water for the frost action, different type of heating and cooling can facilitate the disintegration of rocks. The alternate expansion and contraction of a surface of rock, even though it is most likely not a big force of disintegration that will cause a lot of influence, will cause there to be little fissures and cracks where frost can get into and can make the process go a lot quicker.

Even though water mostly consists of an agent of deposition, it is also one of the greatest suppliers to gradation. Everybody is aware with how water can cut a small pothole in solid rock, and this occurs due to thousands of years of dripping. So even though water is usually an agent of deposition, it at the same time additionally causes the rock to become eroded.