The Relationship Between Denudation and Climate - Essay Example

Chapter Two Summary Chapter Two Summary Chapter two of the book is based on the geomorphic system. The topography of theearth originates from numerous processes, some from the inside of the planet while others are from the outside and other processes are on the planet. The chapter specifically deals with the cycles associated with rocks and water, the processes in which the land surface wears away and builds up, as well as the forces of erosion, tectonics, and the climate. The first part deals with the global cooling and uplift of the earth. The uplift of the mountains has been one of the earth’s most active processes with the Tibetan plateau rising by approximately 4,000 m in the last forty years. The period of mountain rising is directly linked to global climate change through weathering and airflow modification. The geomorphic processes are significant in climatic change because the weathering processes release carbon dioxide into the atmosphere that has great impacts on the climate. The chapter also discusses the cycles of rocks and water. The earth is comprised of the solid lithosphere, the watery hydrosphere, and the gaseous atmosphere. The spheres lead to the exchange of solids, liquids, and gasses in the cycles of water and hydrological cycle as well as the rock cycle. The other important cycle in the three spheres is the biogeochemical cycle that aids in the circulation of chemical elements in the crust, the upper mantle, and the ecosphere. The water cycle refers to the circulation of the water in the meteoric system through the atmosphere, the hydrosphere, and the upper regions of the crust. The process is associated with the circulation of the juvenile water that is associated with the rock cycle and the production of magma. The land phase is significant in the water cycle because it is through it that water is transferred from the land surface back to the atmosphere. In addition to the water cycle, the rock cycle refers to the action of creation and destruction of the earth material, the crust, comprising of the rocks and minerals. The rocks start the decomposition and disintegration processes through the action of weathering. Wind, water, and gravity aid the transportation of the weathering products to the hydrosphere. It is on the ocean floor that deposition of the particles occurs. The burial of the loose rock sediments leads to cementation, compaction, and recrystallization and the result are the formation of the sedimentary rocks. The sedimentary rocks may be converted to metamorphic rocks through deep burial. Granite may also be produced through other deep-seated processes. The three types of rocks may later join in the next stage of the rock cycle. Other significant cycles are the biogeochemical cycles. In this case, the biosphere powers a cycle of oxygen, carbon, nitrogen, hydrogen, and other important earth elements. The elements are exchanged between the environment and the ecosphere in what is referred to as biogeochemical cycles/ processes. The chapter also highlights the interaction between the earth cycle and the water cycle. The process of weathering involves the decay of rocks by chemical, biological, and mechanical agents on the earth’s surface. The weathered sediments may move downhill and down rivers or may stay in the place where the rock is situated. The down slope movement of the rock sediments results from fluid forces and gravity. The entire process that leads to lowering of the ground surface is also referred to as mass wasting. The sum of the entire weathering processes leads to erosion. The later is the acquisition of the earth material by mobile agencies such as water and wind. The sediments can also be carried upslope by the action of moving air, which may be opposite the direction of the flowing water. The water and ice situated in the pedosphere and the weathered part of exposed rock surfaces may be referred to as the solid and liquid components of the weathered part of the mantle. The occurrence of sedimentary bodies results when the forces of deposition outpace those of erosion and where the forces of chemical precipitation go beyond the solution loss. Denudation is also a significant process in the earth forming factors. The measurement of denudation rates is aided by the suspended and dissolved loads of rivers from geological sedimentation. The chapter presents figures giving the measurements of the rate of denudation and soil erosion as well as the back down of the mechanical and chemical denudation by the planet. The suspended sediment load in rivers is controlled by several factors such as the drainage basin area, the drainage basin relief, drainage basin geology, specific discharge, climate, and the presence of lakes. The climate factor is responsible for the suspended sediment load that is affected by the mean annual temperature, seasonality of rainfall, and total annual rainfall. In this case, runoff tends to be generated by heavy rainfall while a significant load of suspended sediments results from heavy seasonal downfall. The relationship between denudation and climate is also highlighted in the chapter. Given any climate, the glaciations of valleys tend to be substantially faster than the normal rates of erosion. The lowest minimum denudation rates, as well as the highest maximum rates, take place in humid temperate climates due to the low temperatures. With all other factors remaining constant, the rate of denudation is brisker in the continental climates. The Savannah, semi-arid, and tropical landscapes tend to denude more rapidly. The rate of chemical denudation may be easier to predict than that of mechanical denudation. Studies have reported that the amount of sediments removed from the continents in the form of solution is not correlated to the average specific discharge. For instance, South America is said to have the highest rate of specific discharge but also has the second lowest rate of chemical denudation. At the same time, the rates of specific discharge in Europe are relatively low though the denudation rate in the region is the second highest. Likewise, the rate of specific discharge in Africa is the lowest as well as that of chemical denudation. In other words, all the continents show varying tendencies to wearing away in factors that cannot be easily accounted for in terms of differences in climate change. However, the control of the chemical denudation processes can be devised from the composition of the major rivers on the planet. The chapter also focuses on the global and regional patterns of denudation. The variation in solute and sediment loads tend to occur in particular regions due to the local effects of the vegetation cover, the type of rocks, among others. The global and regional sediment yields are represented in diagrams. Some researchers have identified relief as the primary factor influencing the rates of denudation with the secondary role being played by climate. Another group of studies has identified climate as the primary factor. However, everyone in the field tends to agree that either climate or relief is the primary factors. However, the problem comes in when the relative contribution of each of the factors needs to be determined. The last part discusses the global climatic systems and the tectonic forces. The two systems have been found to interact in significant ways that lead to atmospheric changes, climatic changes, and precipitation as well as the uplift and denudation rates. The interaction of climate, large-scale landforms, and geomorphic processes take place following three processes. One is the direct impact of the tectonic forces and processes upon the topography while the second process is through the direct impact of topography on climate while the third process is the indirect impact of topography on the rates of chemical weathering as well as the concentration of the atmospheric carbon dioxide. Regional climates can also be influenced by topographical changes such as the uplifting of plateaus and mountains. The factors may also influence the amount of precipitation. The topographical changes may have a significant impact by interacting with the primary components of the climate system of the planet. In other words, the grand processes of matter have a significant impact on the water cycle, the rock cycle, and other land forming processes. Discussion points 1. What makes some regions of the planet look topographically different from the others? 2. How is the water cycle related to the rock cycle? 3. Is the land forming processes similar in all climatic and geographical regions? References Huggett, R. (2007). Fundamentals of geomorphology. New York: Routledge. Read More