Weathering and erosion are some of the major contributors to the shape and features of the landscape. The formation of the landscape's features involves actively collaborating to sculpture the earth’s physical features and provision of debris for the formation of deposition features. By definition, weathering refers to the process of disintegration and decomposition of rocks without moving (in-situ) (Bowen & Pallister, 2001) . Erosion refers to the process of removal of the weathered material by the various agents of erosion and transporting them to a different location other than the point of origin. Water in its liquid state and solid (ice) forms one of the most powerful agents of weathering and erosion in areas that at some point experienced glacial activities (Bland & Rolls, 2016) . This paper discusses weathering and erosion in glaciated areas by focusing on the processes involved in the formation of various features, the resultant, an example of the geographical location of the features.
There are four main processes that facilitate weathering in a glacial environment. They include freezing and thawing, hydrolysis, carbonation, and pressure release. Freezing and thawing are experienced where the diurnal temperature ranges from below to above the water’s melting temperature. When the temperature ambient is above the melting point water, water flows and accumulates in the rocks’ cracks when the water freezes as a result of the drop in prevailing temperature, ice in the cracks increases in volume widening the cracks. The water is then refilled during the next thawing, and the crack widens with the progressive cycles of thawing and freezing. In the long run, the rock is broken down into debris (Guyton, 1998) .
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Hydrolysis involves the replacement of the potassium ions with hydrogen ions in feldspar one of the most abundant rock that forms the continental crust. The process results in the formation of Kaolin. The modification of the chemical composition of the bed-rock compromises its strength exposing it agents of erosion. The process is almost similar to carbonation. Carbonation involves the dissolution of carbon IV oxide in water under low temperature as a result of its increased solubility in water at low temperatures. The solution forms weak carbonic acid that dissolves the carbonates such as those found in limestone. Finally, pressure release is the process by which the bedrock develops crevices as a result of a reduction in the overlying weight caused by erosion of weathered material and thawing of the overlying ice. The crevices are widened and the rock weakened by other processes such as freezing and thawing. The processes of weathering expose the rocks and debris to erosion. Erosion is achieved abrasion and plucking in glacial areas. Plucking involves the physical transportation of debris embedded in ice while abrasion is the removal of debris as a result of the debris being transported in the ice scraping against the bedrock. The activity of erosion and weathering form various feature across the landscape ( Guyton, 1998) .
Some of the features that form as a result of glacial weathering include tors, scree and block field. Tors are a product of weathering and form when a rock outcrop from the process of hydrolysis. The outcrop varies in height, but the typical height range is several meters. Examples of tors include Tors of Datmoor in England. Scree is a collection of sorted pedestals that results from weathering under a vertical cliff. The sorting of the scree is done in a manner that the pedestal increase in size as one head down the slope due to the deposition of the weathered pedestals after thawing. An example of screes includes the screes at the bottom of Mount Yamnuska in Canada. Block field, on the other hand, is a collection of larger shattered boulders that remain in their original positions after weathering. They result in a landscape that is littered with boulders. An example includes those found in the summit of Ben Macdui, the Cairngorms in Scotland ( Guyton, B. (1998) .
The combined action of weathering and erosion on glacial areas also result in distinct features such as the formation of cirques, u- shaped glacial valleys, tarns, and arête as illustrated in figure 1. A cirque forms after accumulated ice starts to move and leave a depression as a result of plucking away debris and abrasion. The formation of the cirque is enhanced by debris breaking off its headwall and then being used through abrasion to improve the depressions depth. Examples of a cirque include the Dana glacier of the Yosemite national park in the USA. When the cirque is filled with water to form a dam or lake, it is called a tarn; examples include the Paternoster lakes in the Alpines. As the glacier flows down the slope, it utilizes the plucking and abrasion to develop a large U shaped valley. The valley is called a U shaped valley unlike the V-shaped river valley, and the glacial U-Shaped valleys have a wide base with overhanging stip cliffs. An example includes the Bridalveil Falls of the Yosemite national park in the USA. The formation of several cirques around a peak forms a narrow ridge of rock separating the cirques. The narrow ridge is called an arête. The arête can also form when two U shaped troughs erode parallel to each other. An example of the arête is the Half Dome arête of the Yosemite national park in the USA ( Guyton, 1998) .
Figure 1: A figure indicating the various glacial erosion features
Note: Adopted from officers IAS academy. Copyright 2018. Retrieved from http://officersiasacademy.blogspot.com/2016/04/landforms-created-by-glacier.html
In conclusion, weathering and abrasion play a crucial role in the shaping of the landscape. The two processes work together in the realization of many of the physical feature. For instance, in glaciated areas, weathering contributes to the formation of tors, scree slopes, and block fields. The features are mostly formed as a result of hydrolysis, carbonation, freeze and thawing and pressure release. However, the weathering and movement of the debris results in formation of other features such as the cirque, u-shaped glacial valleys, tarns, and arête. Ice erosion mainly utilizes plucking and abrasion of the weathered material to form the mentioned features. The features of the glaciated areas are spread across many conservancies such as the Alpines and the Yosemite national park in the USA.
References
Bland, W., & Rolls, D. (2016). Weathering: An Introduction to the Scientific Principles . Routledge.
Bowen, A., & Pallister, J. (2001). A2 geography for AQA specification A . Oxford: Heinemann Educational.
Guyton, B. (1998). Glaciers of California: Modern glaciers, ice age glaciers, origin of Yosemite Valley, and a glacier tour in the Sierra Nevada . Berkeley: University of California Press.
Landforms created by glacier. (2018). Retrieved from http://officersiasacademy.blogspot.com/2016/04/landforms-created-by-glacier.html
