There are many forces that originate from the earth’s core and mantle. There are many theories that tend to explain these processes such as the convectional theory. When these massive movements occur, massive forces are transmitted, that end up moving the earth’s crust. Due to these occurrences, the huge continental plates are forced to move, which causes them to collide. One continental plate can slide to rise above another, or push against each other to result to uplifts such as folds. Mountain ranges such as the Himilayas were formed in this manner when the Eurasian and Indian plates collided. This form of uplift is known as the orogenic uplift.
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On the other hand, when there is erosion on the mountain range that gradually removes the crust materials from the surface, this surface becomes lighter as a result of the removal of weight and the pressure within will force the land to bulge outwards resulting to uplift. This is referred to as the isostatic uplift. It can be experienced during the post – glacial rebound after the melt of the ice sheets or glaciers.
Plate tectonics can also result to the massive continental plates moving away from each other. When this occurs, there are fault lines (lines of weakness) formed between them. This eventually leads to a sink between the plates creating low land levels and valleys that could even be below the sea level. In other words, these geographical processes results to the creation of landscape uplifts and even valleys that structures or shapes the appearance, shape, profile or the topography of the landscape. However, these creations on the earth’s surface are usually reshaped by some other artificial and natural processes all together – the processes of erosion and deposition. They also lead to the formation of sedimentary and metamorphic rocks (Fowler pg 313).
Erosion is the process by which broken or weathered crust materials are moved from one surface to another. Weathering refers to the breaking down of rocks and minerals found in or on the crust to smaller particles that can be carried away easily. Unbalanced and extreme heating and cooling of the earth’s crust, water, ice and human activity are all factors contributing to weathering; it can be physical or chemical in nature of occurrence (Partheniades & Emmanuel pg 9).
Erosion of these materials can also be caused by a number of factors i.e. the blowing wind can carry away light and loose materials from one land surface to another, this form of erosion is rampant in open areas without wind barriers and erosion obstacles. Water especially the moving river can carry these materials downstream where they get deposited. More severe forms of erosion like landslides and mudslides involve rapid movement of large landmasses by gravity over a steep landscape. When it occurs gradually over a long time, it is referred to as a creep. These forms of erosion remove the protruding uplifts with the aid of weathering to flatten the tops and form plateau like structures, or even wipe the whole formation; hence reshaping the landscape by changing the surface elevation (Toy, Terrence , George & Kenneth pg 171).
The other process that works hand in hand with weathering and erosion in shaping the landscape is deposition. It is the laying down of the eroded materials or sediments on a different region. It occurs when the river or the wind slows down in the cases of water and wind erosion respectively (Thorpe and Showick 441). This normally happens in the valleys and other low altitude surfaces where sediments are usually carried, hence, raises the sunken surfaces.
Therefore, the external forces of erosion and deposition help in the landscape development after uplift and other plate tectonics processes (Briggs and Smithson 307).
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Fowler, C M. Richard. The Solid Earth: An Introduction to Global Geophysics. Cambridge, UK: Cambridge University Press, 2006. Print.
Partheniades, Emmanuel. Cohesive Sediments in Open Channels: Properties, Transport, and Applications. Amsterdam: Butterworth-Heinemann/Elsevier, 2009. Print.
Thorpe, Edgar, and Showick, Thorpe. Pearson General Studies Manual: For the Upsc Civil Services Preliminary Examination. Chandigarh: Pearson Education, 2009. Print.
Toy, Terrence J, George R. Foster, and Kenneth G. Renard. Soil Erosion: Processes, Prediction, Measurement, and Control. New York, NY: Wiley, 2002. Print.