Hydrosphere, Biosphere & Lithosphere - Essay Example

?Geography: Hydrosphere, Biosphere & Lithosphere Describe the paths of water through the hydrologic cycle. Explain the processes and the energy gains and losses involved in the changes of water between its 3 states. Operationally, we often most concerned with water does when it reaches the solid earth, both on the surface and in the sub-surface. Explain the relationship between the saturated zone, the water table, a ground water well and the cone of depression, all within the sub-surface. In the hydrological cycle, the water circulates between the oceans, the atmosphere and the continents. The water can exist in any of the three states during the transportation, i.e. as vapor expressed as humidity, as liquid in the form of droplets or as solid such as in the form of ice crystals or snowflakes. During the various process involved in the hydrological cycle, the quantity of water or 'water balance' that changes between inflow and outflow can be estimated based on the principle of conservation of mass. The movement of the water including the formation of water vapor is driven mainly by solar energy although other forces are also involved. The water evaporates from the surface of the ocean during the vapor phase. It then usually either falls as rain onto the surface of the earth (liquid phase) or as snowfall (solid phase) under the process of precipitation, and on land a large portion of it usually flows in rivulets and rivers from the mountain tops to the seas in liquid form under the influence of gravity (surface runoff). Some of the water reaching land surfaces is also absorbed by the soil (infiltration) which can then follow one of several paths such as directly to the atmosphere by plants through transpiration. Within the sub-surface, a 'saturated zone' develops near the water table which is the surface that separates this zone from the zone of aeration (Monroe et al., 2006: 524). The saturated zone develops from the capillary rise of water in the pores of the soil, sediments and rocks. When a water well is used to pump the groundwater, the lowering of the water table in the area of the well can create a 'cone of depression', which refers to the loss of water having exceeded its inflow. 2.The food chain is a valuable concept in biogeography. Give an example of a specific food chain, labeling the various levels of the food chain. After looking at characteristics of food chains, explain how a geographer’s approach to the study of organisms might be different than biologist’s study of organisms; what would each try to emphasize more than the other? What exactly is a biome? Compare/contrast the concept of the biome with that of the zoogeographic region. Compare/contrast the floral characteristics of 2 of the following biomes: Desert, Tundra, Midlatitude Grassland and Boreal Forest. An example of a simple three-step specific food chain is given below with the deer as the herbivore and the lion as the carnivore. Food chains indicate a unidirectional transfer of energy beginning with the producers (as autotrophs) and ending with the topmost carnivores. Knowing the food chains help in identifying the interactions and interdependence between living organisms. The distributions of the energies and biomasses in each food chain are typically though not always pyramidal. In reality, many food chains have at least four steps and several are intricately linked forming food webs. Grass (producer) > Deer (herbivore) > Lion (carnivore) In studying the characteristics of food chains, a geographer would be more interested in the wider ecosystems; in how the components of the chain are interdependent, in the flow of energy through the whole system between the different trophic levels, in examining the levels of biomass, and so on. A biome is a natural ecological grouping of animals and plants on the basis of climates, i.e. “all the ecosystems taken together in a given geographical area having the same type of climate” (Bharatdwaj, 2006: 100). Other environmental factors could also differentiate biomes but they are distinguished because the flora and fauna of a biome are fairly homogenous. There are six major types of earth based biomes, namely grassland, temperate forest, tropical forest, coniferous forest, desert and tundra, and two major types of water based biomes, namely fresh water and marine. As such, biomes differ from zoogeographic regions, which are more general regionalisations specifically for animals, and therefore based not on environmental factors but on taxonomic similarities. In comparing the tundra with a boreal forest, it is noted that the climatic conditions in a tundra are typically arctic so no deep root systems are to be found. The word itself literally means a 'treeless plain'. However, some plants such as low shrubs and reindeer mosses do exist. In a boreal forest, which lies close to a tundra as in Canada/Alaska and Siberia, the flora is also relatively poor but a greater variety exists and it consists mainly of coniferous trees. 3.Theorize the difference in soil development in adjoining soils developed on forested, sloped area versus a grassed flat area. What are the soil-forming factors? Explain the importance of the nature of the parent material to soil formation and type. Then, cite at least 2 examples in which the influence of parent materials might be outweighed by other soil-forming factors. Explain the “struggle” between the internal and external processes in shaping the Earth’s surface. What are the different ways that the surface of the Earth is changed over time? Soil development is affected by such factors as climate, the presence of organic matter, relief and parent material, and by time (Gabler et al., 2006: 340). Soil formation on a grassed flat area compared to an adjoining forested, sloped area is more likely to be affected by wind erosion whereas on the sloped area, it is more likely to be affected by water runoff. Parent material refers to the material in which soil formation takes place. Their importance is reflected in the fact that they determine the structure and minerals to be found in the soil following their breakdown. However, in biomes such as the tundra and the desert, other factors such as climatic and topographical factors could outweigh the influence of parent materials. The climate also exerts a greater influence than the parent material, for example, in a chernozem soil (arid-humid boundary), which is formed on both light and heavy textured soils and is very fertile (Jenny, 1994). This highlights the struggle between the internal and external processes in shaping the Earth's surface in which both sources of factors that affect soil formation seek to be dominant over the other. The surface of the Earth is actually changed over time by various physical, chemical, biotic and human processes (NRC, 2010). 4.Describe the general sequence of events in continental drift since the time of 5 separate continents 450 million years ago. What is the difference between the older continental drift theory by Wegener and the more recent plate tectonic theory? Plate tectonics theory explains many seemingly unrelated phenomena. Explain how the patterns of volcanoes and earthquakes related to plate tectonics. Explain several pieces of evidence that combine to make the theory of plate tectonics the one that is generally accepted. According to Alfred Wegener's detailed theory of continental drift, a single continent originally existed named Pangaea. This then broke apart into two pieces in the Jurassic period. Further fragmentation continued to eventually evolve into the five continents of the present day. He suggested that the lighter portions of the earth's crust float atop the underlying denser layer. The Americas for example, drifted westward which opened up the Atlantic Ocean. He observed that the shape of the land masses seemed to fit together like pieces of a jigsaw puzzle. Fossil evidence also supports the theory and the modern theories of plate tectonics lends additional support. Plate tectonics theory actually explains a number of other seemingly unrelated phenomena as well such as crustal structures, seismic activity, sea-floor spreading and volcanic activity. The plates are pieces of the top layer of the lithosphere, i.e. the earth's crust. Deformations are believed to occur where the plates interact. Thus, many earthquake zones and volcano sites are to be found at plate boundaries. The mountain ranges for example, are formed from their collisions. Earthquakes occur in places where the earth's tectonic plates contain faults in the form of fractures or from being otherwise weak. Some volcanoes arise in places where the plates diverge and intermittently along the rift if there is sufficient pressure, and some 'hot spots' exist even in the middle of plates (BEP, 2010:16). One of the major pieces of evidence in support of the theory of plate tectonics is the existence of magnetic stripes on the ocean floor lying parallel to ridges (Gubbins, 1990: 316). Other evidence comes from its ability to predict global tectonics and from deep sea drilling, 5.Provide a reason why some scientists believe the Pleistocene is over and a reason why other scientists believe we are now in an interglacial stage. Some believe, for example, that since areas of pack ice and glacial ice still exist we are still in an ice age. Others, on the other hand, seeing the rapid retreat of ice and snow pack in many areas, believes that this period of glaciation has ended. So, using some other justifications, why do we see some differences in interpretation? Is there some scientific data available that can support both sides view? If so, provide it. Why hasn’t this controversy been solved? What impact does this division of views have on the public policies that are enacted by state, national and international bodies? The supposed end of the Pleistocene was marked by an increase in the global mean temperature by 4-7?C supported by fossil evidence, and mass extinctions of large mammals (Soule & Orians, 2001: 179). Other scientists believe we are presently in an interglacial stage called the Holocene epoch because of climatic similarities with past interglacial periods (Butzer, 1972: 376). However, the existence of areas of pack and glacial ice suggest that technically the ice age has not ended although the rapid retreat of ice and snow pack in many areas suggest that global warming is taking place due to rising temperatures. One reason for the differences in interpretation is the limited meteorological records. Scientific data supports evidence for global warming, for example, by observing some migrations of animals more towards the poles, comparing with proxy data of past interglacial temperatures, boreholes and tree rings, glacial retreats, CO2 levels, etc. However, the lack of long term data makes it unclear whether the rise is marginal or a long term trend or whether temperatures will fall again so the controversy cannot be solved yet. Public policies are impacted by this division of views because the uncertainty makes it unclear which direction various bodies should take. Global warming would lead to rising sea levels which has huge implications especially for people living in coastal and low lying areas. Works Cited BEP. 2010. Plate tectonics, volcanoes, and earthquakes. Britannica Educational Publishing. The Rosen Publishing Group. Butzer, Karl W. 1972. Environment and archeology: an ecological approach to prehistory. Taylor & Francis. Bharatdwaj, K. 2006. Physical geography: biogeography. Discovery Publishing House. Gabler, Robert E.; Petersen, James F. & Trapasso, Michael. 2006. Essentials of physical geography. Cengage Learning. Gubbins, David. 1990. Seismology and plate tectonics. Cambridge University Press. Jenny, Hans. 1994. Factors of soil formation: a system of quantitative pedagogy. Dover Publications. Monroe, James Stewart; Wicander, Reed & Hazlett, Richard W. 2006. Physical geology: exploring the earth. Cengage Learning. NRC. 2010. Landscapes on the edge: new horizons for research on Earth's surface. National Research Council (U.S.) Committee on Challenges and Opportunities in Earth Surface Processes. National Academies Press. Soule, Michael E. & Orians, Gordon H. 2001. Conservation biology: research priorities for the next decade. Island Press. Course text: Hess, Darrel, 2011 McKnight's Physical Geography, A Landscape Appreciation, 10th Edition Read More