Exploring the Grand Canyon: Nature's Deepest Gorge - Essay Sample

Introduction

The canyon is a deep gorge in which a river flows. A canyon is a landscape of degradation formed when the rate of denudation exceeds the deposition of materials. An excellent example of a canyon is the Grand Canyon in Arizona. The cross-section of the Grand Canyon consists of layered bands of red rocks that can possibly reveal a very long time of its geological history. The depth of the Grand Canyon has been estimated to be one mile and the width 10 miles. Moreover, it is 277 miles in length (Pitty, 2020). River Colorado flows through the Grand Canyon forming numerous rapids and sweeping vistas.

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The Grand Canyon was formed by a combination of various external processes such as weathering of rocks, mass wasting, and erosion of loose materials by water and ice over a long period of time (Huggett, 2016). The geomorphic agents involved in the formation of this landscape were water and ice. These agents were capable of corroding and transporting the weathered materials downstream causing the gradual formation of a deep valley.

The following is the possible reason for the formation of the Grand Canyon landscape. The massive falling of rain and ice in northern Arizona provided the morphological agents. Water and ice are well-known morphological agents whose capability cannot be underestimated. Water and ice have a high capacity to erode land surface by loosening the rock materials on the surface of the ground. As the water flows down the valley, it gains a significant force that is able to sweep away loosened materials downstream. Meanwhile, as the river flows downstream, the water continuously erodes the river banks and river beds loosening more earth materials. The eroded materials are carried away and transported to faraway destinations downstream (Huggett, 2016). The persistent external processes of erosion and transportation of eroded materials led to the formation of a vast region of a deep valley. Currently, the erosion and transportation of materials still continue and the Grand Canyon is believed to widen and deepen continuously.

River Meander

A river meander is a landscape of both degradation and aggradation. It starts with a small bend in the course of a river due to differential erosion of the river bank. When such a bend occurs, the water flowing on the outer side of the bend tends to have a higher rate of flow as compared to the flow rate to the inner bend (Bursztyn et al., 2015). Swift flow of water encourages active erosion of riverbank while slow water flow encourages the deposition of eroded materials. Therefore, the river deposits materials carried from the upper stream to the inner bend where the flow rate is slow. At the same time, the faster flow of water on the outer side of the bend causes more erosion making the river to advance outwards (Pitty, 2020). As this process continues, more bends occur and get closer to each other leading to the development of a morphological landscape called river meander. Suppose the river rejuvenation occurs, water may overflow and cause two bends to come together (Anton et al., 2015). In such situations, the water will flow through the shortest distance created leaving a curved valley with stationary water. The section of the meander cut and left remains with water and can be described as an ox-bow lake.

The Horseshoe Bend in the course of River Colorado is an excellent example of a meander. The Colorado River cuts into the bedrock as it advances downstream forming this spectacular site just below the Glen Canyon Dam (Anton et al., 2015). The landscape formed here is best described as the incised meander since the river cuts into its bedrock. It was formed through external processes of degradation of the riverbank by the water flowing along the stream (Pitty, 2020). The interplay between weathering, erosion, and transportation of the weathered rock materials led to success in the formation of the incised meanders.

Possible reasons for its formation of the Horseshoe Bend landscape along River Colorado may be due to a significant fall in the river's base level behind the Glen Canyon Dam (Bursztyn et al., 2015). The fall in the river's base level provided an excellent power for vertical erosion enabling the river water to downcut into the bedrock. The persistent cutting of the bedrock led to the formation of this breathtaking landscape.

Knickpoint - Niagara Falls

A knickpoint is part of a stream where the gradient changes abruptly due to change in the rate of erosion (Anton et al., 2015). At the knickpoint, usually falls occur. An excellent example of this landscape is the Niagara Falls to the southern end of the Niagara Gorge (Huggett, 2016). Knickpoint is a landscape of degradation where the river actively degrades its bed cutting it deeper to form a fall. As the water drops down the depth of the fall, it generates more water power by which it pounds onto the river's bedrock causing a continuous cut.

The Niagara Falls were formed by external processes of active river erosion and transportation of materials downstream. It has an elevation of approximately ninety-nine meters and a height estimated to be fifty-one meters. At this point, the flow rate of water is approximately 2,400 m3/s (Huggett, 2016). The speed of water is large enough to carry the suspended materials over a long distance. It can also cause additional abrasion of the river bed and riverbanks to cause more erosion. The persistent abrasion and active erosion of water deepened the riverbed leading to the formation of deep falls - the Niagara Falls.

The possible reason for the formation of the Niagara Falls was due to glacial recession at the end of the last ice age. It is believed that after the last ice age, large volumes of water from the Great Lakes flowed through the Niagara Escarpment towards the Atlantic Ocean. The large amounts of water caused tremendous erosion at the Niagara escarpment (Pitty, 2020). At the southern end of the Niagara Gorge, the soft rocks were easily eroded, leading to the formation of deep falls as the water advanced downstream (Anton et al., 2015). The digging deep into the riverbed was due to the persistent effects of glacial activities as well as erosion by water. The ice played a part in weathering of rocks through differential freezing and thawing. The loosened rocks were swept away by the water power downstream, thereby creating more room for continuous weathering. The process of weathering and erosion over a long time deepened the falls making them as they are today.

References

Anton, L., Mather, A. E., Stokes, M., Munoz-Martin, A., & De Vicente, G. (2015). Exceptional river gorge formation from unexceptional floods. Nature communications, 6(1), 1-11. Retrieved from https://www.nature.com/articles/ncomms8963?origin=ppub

Bursztyn, N., Pederson, J. L., Tressler, C., Mackley, R. D., & Mitchell, K. J. (2015). Rock strength along a fluvial transect of the Colorado Plateau-quantifying a fundamental control on geomorphology. Earth and Planetary Science Letters, 429, 90-100. Retrieved from https://www.sciencedirect.com/science/article/pii/S0012821X1500477X

Huggett, R. (2016). Fundamentals of geomorphology. Routledge.Pitty, A. F. (2020). Introduction to geomorphology. Routledge.