ÖDEV 5 TEXT

Mountaintop Removal Mining

  From below, everything appears as it should. A mountain thick with trees, wildlife foraging for food, and the undisturbed natural beauty of the rocky landscape. However, looking down on that same mountain from the air, viewers observe quite a difference. Instead of seeing a majestic peak, there is a flat plateau sitting hundreds of meters below the hills surrounding it In the Appalachian Mountains of the United States, a new form of coal mining is taking place. Called mountaintop removal mining, it is a form of surface mining that is stirring up a large amount of controversy.

 The process of mountaintop removal mining begins with clearing the land of all trees and removing the topsoil. The trees are usually sold to lumber companies and the topsoil is put aside for reclamation once the mining is completed. Miners then use explosives to expose the coal. The resulting debris is then pushed into nearby valleys to create what is called a valley fill. An excavator uses a bucket to scoop up the coal on the surface. Then the coal is taken to a processing facility where it is washed, resulting in millions of gallons of wastewater called "slurry." The pools of slurry are usually contained by earthen dams near the coal plant. After all the coal has been mined from the mountain, the topsoil that was removed at the beginning is replaced, and seeded to grow vegetation. However, it is not required that the land be returned to its original state.

There are some advantages to mountaintop removal mining. It is the most cost-effective method of coal mining, cheaper than underground mining per ton of coal. Using this process, coal production increased from ninety-five million tons in 1977 to 181 million tons in 1998. Mountaintop removal mining uses explosives and heavy machinery to extract the coal. This makes it a much faster method than underground mining. Another benefit to coal companies is that the machinery allows the work to be done with fewer employees. Also, it is safer for miners in comparison to underground mining since coal seams are accessed from aboveground instead of underground, removing the risk of cave-ins. In some areas of Central Appalachia, mountaintop removal mining sites allow for development of land where stores, hospitals, schools, and industrial parks can be built.

  Despite the benefits of mountaintop removal mining, it takes a heavy toll on the environment and the people who live in areas near mining sites. Residents of mining communities have to deal with the noise and resulting flying rock from the destruction of the mountaintop. There are also damages to house foundations as a result of the ground shaking explosions. The dust from these explosions contains sulfur compounds that can cause corrosion and pose health risks. It settles into air vents and on anything outside, such as lawn furniture and playground equipment. The advantage the coal company receives from employing fewer workers means residents of Appalachia are at a loss for jobs in an area where most live below the national poverty level. Due to the environmental pollution of the mining communities, it is unlikely other industries will move in and supply new jobs. Valley fills have buried an estimated 1,931,212 meters of streams that are now contaminated. A by-product of valley fills is acid mine drainage, which accumulates in groundwater systems. This results in acidic water high in magnesium, aluminum, and iron that contaminates drinking water, streams, rivers, and lakes. Some coal companies have bottled water delivered to whole communities because the pollution from their mining operations causes groundwater systems to become undrinkable. Another concern is the breaking of slurry dams, which can release a flood of wastewater containing chemical and metal toxins such as mercury and arsenic into homes, schools, and water supplies.

 There are distinct advantages and disadvantages to mountaintop removal mining. Since ninety percent of mined coal is used in the production of electricity, it is a valuable resource with a  high consumption rate. The debate is whether or not the benefit of mining coal in a cost- productive, efficient manner is worth the impact it has on the environment and residents of mining communities. Much of the evidence indicates that more coal is not worth the destruction of the Appalachian Mountains or its residents, especially when considering the potential damage that can be caused if mountaintop removal mining continues.

Effects of Temperature on Elevation

Imagine  two  of  the  world's  largest  cities,  New  York  and  Los  Angeles,  submerged underwater  due  to  natural  causes.  What  "natural  causes"  could  lead  to  such  a  disaster? Immediately, thoughts of earthquakes and flooding come to mind. Yet, the explanation might be something much more subtle. A recent geological study has found a correlation between the temperature of the Earth's crust and the elevation of its surface. Using North America as an example, the study reveals how increases or decreases in temperature can cause changes in the altitude of any given place on the continent

Previously, scientists believed that variations in the thickness and composition of crustal rocks alone were the reasons for the elevation and buoyancy of different areas in North America. It was thought that elevation was the result of tectonic plates in. the Earth's crust that collided to build mountains, sink the sea floor; and contribute to volcanic activity. They did not consider the heat that makes rock expand as a factor. When rocks are heated, they become less dense and more buoyant, an occurrence known as thermal isostasy.

A new study of elevation takes into consideration not only the composition of the rock in the upper mantle and crust, but also its temperature. Ice floats because when water freezes, it expands and becomes less dense. Similarly, when heat is applied to rock, it also expands and becomes less dense. The heat that aids in buoyancy and maintains elevation is found in the Earth's interior and from the radioactive decay of elements in the Earth's crust. The significance of taking into account temperature, composition, and thickness of crustal rock is that it allows scientists to examine other heat sources that may affect elevation, such as "hot spots." Hot spots are places in the Earth's mantle where rocks melt and create magma.

The city of Seattle, Washington in the northwestern United States is at sea level. It is located on rock that is at below average temperature for crustal rock. The slab beneath the city is insulated from the heat beneath it If it were not, then Seattle's elevation would rise to I ,813 meters above sea level. The increase in temperature would expand the crust under the city and make it more buoyant, thus increasing the altitude. It stands to reason that if cooling makes elevation fall, then heat makes it rise. Denver, Colorado is located in the Rocky Mountains. It is called "The Mile High City" because its elevation above sea level is exactly one mile. If ihe temperature beneath the mountains dropped low enough, it is estimated that Denver would go from 1, 609 meters above sea level to 222 meters below sea level.

Clearly, temperature has a large impact on elevation. It will take billions of years for the rock beneath North America to cool and become dense enough to submerge most of the continent. However, monitoring elevation changes can aid scientists in predicting temperature shifts on the Earth's surface. In some areas, increases in altitude could signal the beginnings of volcanic activity as magma heats up crustal rock. This would allow for advance warning of volcanic eruptions.