Physical Weathering

Part 1

This is the kind of weathering where the earth’s atmosphere acts on masses of large rocks and breaks them down into smaller sizes of the same rock material. A good example can be pieces of granite at the bottom of a granite cliff.  This weathering leads to change of the rock size but does not change the kind of the rock. This process of weathering is caused by temperature change, hydro fracturing and frost wedging or by roots of trees and shrubs. Summer high temperatures cause the expansion of the rock material and low temperatures of winter makes the rock to contract. This expansion and contracting weakens the rock over the years making it to crack and break off. For hydro fracturing and frost wedging, water freezes inside tiny rock cracks, beginning from outer surface towards the inside. This freezing causes the pressure from trapped water and ice to increase and freezing of water continues deeper in the rock and thus splitting it. In addition as plants grow, they push their roots against the rocks cracks in surface, weakening and thus breaking them off (Petersen, Sack and Gabler, 373).

Part 2

Sedimentary rock is the most material that is most susceptible to physical weathering since it is more porous and water can permeate through such rocks easily and the cement it is made of is a mineral that can easily be dissolved in water. Physical weathering is most likely to happen in humid climate where there are a wide range of annual temperatures. It leads to breakup of materials and detachment of fragments thus making the rocks very unstable and these rocks becomes susceptible to external influences that may lead to landslide (Petersen et. al 373).

 

Part 3

A river or stream can transport materials in three different ways which include; in solution form, in suspension and in the rivers or streams bedrock. In the first case, mineral matter that are have been dissolved by water from the bedrock is transported in solution. Such common minerals consists of magnesium, calcium and bicarbonate. Most of the solution comes from the groundwater that has seeped into the stream or river. Before reaching the stream, this groundwater travels through bedrock fractures eroding the rock chemically along the way. In the suspension form, the water appears muddy since it is transporting rock materials. These materials consist of fine sand, clay and silt. Though the materials are heavier than water, they are stirred up by water turbulence, preventing them from sinking.  A river or stream can also transport materials in bed load. The bed load has pebbles, sand and boulders which cannot be transported in suspension since they are too heavy. They are moved along the bed especially by floods (Stephen, 1892).

Part 4

The difference between stream competence and stream capacity is that stream capacity is applied in the measurement of the size of particles that form the sediment while capacity is applied in the measurement of the quantity of the sediments. In other words, stream competence refers maximum size of particles of a rock that a can be transported by a stream and whose measurement is done through the diameter of the particle in inches or centimetres. Stream capacity refers to the total amount of materials that a stream can transport and whose measurement is done in terms of weight per each unit time (Stephen, 1892).

 

 

Part 5

Mass movement is divided into four types namely creep, landslides, frozen ground phenomena and subsidence. Creep happens due to superficial materials of rock debris or soil moving slowly downslope and this is usually shown by accumulation of the materials at the upper slope side of trees or field boundaries by posts bending , trees’ leaning or by tuff roles. It happens after particles are displaced at right angles. The frozen ground phenomena result from inter bedding of different rocks and saturation of sediments that are fine-grained like clays cause squeezing of bigger beds that involve cambering of tree faces which are exposed in a slope and the bulging of the beds below the valley floors. Landslide involve various types of occurrences which depend on failure along a plane beneath the surface. Landslide consist of various types such as block slide, rockslide, mudslide and debris slide. Subsidence results from various causes which include mining, subsurface solution, marine erosion, ground ice melting and subsurface erosion. Settlement of the layers of the ground surface may lead to may cause sinking of the surface due to consolidation resulting from surface loading (Derbyshire, Gregory, and Hails, 64).

 

References

James Petersen, Dorothy Sack, Robert E. Gabler. Fundamentals of Physical Geography: Cengage Learning.2. (2014).373-374

Butz, Stephen D. Science of Earth Systems. Australia: Delmar Learning, 2004. 188-195

Derbyshire, E, K J. Gregory, and J R. Hails. Geomorphological Processes.  1981. Internet resource.64-65