Weathering, erosion, and mass-wasting effects

Weathering, erosion, and mass-wasting decompose and deposition processes on the earth’s surface. Topographical changes, such as landscape changes and some landform growth, are caused by these processes (Pipkin, Trent, Hazlett, & Bierman, 2014). Weathering is the physical or chemical deterioration and alteration of rocks near the surface of the earth. Erosion is the process of wind, ice, water, or gravity transporting already withered materials from the earth’s surface to lower ground. The transportation of rocks or soil to reduce floor mainly by gravity is known as mass-wasting (Dutch, 2013). This paper examines a Capital News article about a landslide in Malaysia on October 21, 2017. The relationship between this article and the three processes is that Landslides are among the events directly caused by either small or large scale mass-wasting, the weathering of rocks leading to instability of hills, or abrupt erosion, especially by gravity. According to Presse (2017), the landslide occurred in Gorge Town and led to the death of more than 14 workers working at a construction site which was badly affected.

Scientists raised concerns that the reason for the landslide was as a result of the increasing rate of development and constructions being conducted in the hillslope areas (Presse, 2017). It was verified that the right slope cutting measures. However, weathered materials and rocks affected the stability of the hill slopes leading to the inevitable abrupt collapse of the slope by gravity (Presse, 2017). There was also some speculations that the wet weather could have also played a role in the landslide.

Weathering

Weathering, Erosion, and Mass-wasting play an essential role in the formation of new sedimentary rocks in the rock cycle. Over geological time the processes transform hard rocks into smaller sediments and soil leading to redeposition (Pipkin, Trent, Hazlett, & Bierman, 2014). According to Presse (2017), the Malaysian landslide was partially caused by the weakening of hill slopes’ due to weathering of rocks. It is however not clear on the type of weathering There are various types of weathering, each leading to different results The first one is Mechanical Weathering which is the physical wearing off without a change in the chemical composition.

Examples of chemical weathering include; Exfoliation whereby the pressure in the rocks is released along alignments and slabs of the rock leading to their break off. Another one is the Frost Wedging whereby water freezes and expands hence applying pressure to the surrounding rocks leading to gradual weakening and breaking in cycles. Next is the change in temperatures which causes the expansion and contraction of rocks and its continuity leads to weakening and cracking of the rocks. In most cases, temperature changes speed up the weathering process. Salt wedging is also a mechanical weathering form whereby salt crystallization and the growth of the crystals exert pressure to surrounding rocks causing them to weaken and eventually crack (Dutch, 2013).

The second category of weathering is the decomposition and weakening of rocks due to chemical reactions and processes. There several types of chemicals with the first being carbonation. This happens when rainwater mixes with carbon dioxide to form a weak carbonic acid that simultaneously reacts with the rock. Other forms include; oxidation, hydration, and hydrolysis (Dutch, 2013). Biological weathering is the third category. This is the disintegration of the rocks that have already started decaying to smaller particles. This is caused by the growth o plants and the spreading of roots between rocks’ cracks (Dutch, 2013).

Erosion

After the weathering of rocks, erosion transports the sediments from their natural location to another. The agents of erosion are water, wind, ice, and gravity. Erosion by water which is also called fluvial can be broken down into splash, sheet or gully erosion. Water eases the loosening of particles and transports them forming gully-like channels. Wind, on the other hand, picks the particles and transports them through air or sand-blasting processes (Pipkin, Trent, Hazlett, & Bierman, 2014). Ice erosion occurs in form of periglacial and glacial processes. As ice moves downslope it causes abrasion and friction with rocks and hence eroding their surfaces and leaving scrapes or groove-like structures. Finally, gravity erosion facilitates the movement of withered particles without the help of neither water, wind or ice. These agents can, however, act as a catalyst (Dutch, 2013).

Mass-wasting

Mass- wasting is the sudden and rapid erosion of materials under the influence of gravity. Mass wasting occurs very fast as compared to erosion and is catalyzed by the landscape and topography of the area. The Malaysian landslide was majorly a mass-wasting event in with the indirect help of other erosional agents (Presse, 2017). Landslides are the natural movement of withered particles at an incredibly fast speed often causing destruction to anything along its way. Most landslides are triggered by either rainfall, snow, ice or an earthquake. However, according to Presse (2017), none of these caused the Malaysian landslide.

Other forms of mass-wasting include; rock falls, mudflows, slumps, and creeps. Rock falls are as a result of a higher potential energy of dislodged rocks which transforms to kinetic energy and thus rolling downhill (Pipkin, Trent, Hazlett, & Bierman, 2014). The dislodging of rocks may be caused by either of the above weathering causes. Mudflows, on the other hand, are caused by heavy rainfalls that erode huge segments of soil, sediments, plants or any other debris down valleys. They are a major threat to any obstacle on their flow path. Another form of mass-wasting is the slump whereby there is a collapse or break off of rocks or soil chunks from hill slopes. Finally, creep is the gradual movements of a complete unit of a slope. This is the slowest mass-wasting event (Dutch, 2013).

Conclusion

The above three depositional processes lead to the formation of several topographic features such as gullies and formation of new sedimentary rocks. However, they are also dangerous and destructive when not planned for. For instance, the Malaysian landslide led the death of more than a dozen people. Such occurrences can, however, be predicted and people cautioned especially for those leaving in low grounds. The three processes also portray a sense of interrelation and interdependence amongst themselves.

References

Dutch, S. I. (2013). Earth science. Earth materials and resources. Ipswich: Salem Press.

Pipkin, B. W., Trent, D. D., Hazlett, R. W., & Bierman, P. (2014). Geology and the environment. Belmont: Cengage Learning.

Presse, A. (2017). Fourteen feared dead in Malaysian landslide » Capital News. Capital News.

Retrieved 29 November 2017, from https://www.capitalfm.co.ke/news/2017/10/fourteen-feared-dead-malaysian-landslide/