Geology Reference
In-Depth Information
unsafe for drinking. Similarly, the contaminated water from the fracking process may
flow into nearby surface waters, damaging ecosystems as well as human health.
Another danger with fracking is the destabilization of the rocks that are fractured. Re-
gions where fracking is practiced often begin to experience small but persistent earth-
quakes, indicating that the bedrock is shifting where previously it was stable.
Removing Mountaintops
In regions such as the Appalachian Mountains of North America, coal deposits are found
in layers of rock forming the mountainous landscape. The coal mining industry, with the
aid of huge land-moving machinery, has developed ways to extract as much coal as pos-
sible — rather than mine in underground tunnels, it simply removes the overlying layers
of rock. In other words, the key is to remove the top of a mountain.
This process of coal extraction begins with removing all the trees and vegetation. Then
each layer of non-coal-bearing rock is scraped away. After the layer of coal itself is
stripped away, the material that has been removed may be replaced, or it may not. Often
the removed materials are left in nearby valleys, polluting rivers and changing the shape
of the landscape. After all, when a mountain of rock and sediment is removed, it must be
deposited somewhere else.
Developing Deserts
Many regions of the world experience
desertiication
or the transition of productive land
into barren, useless land as a result of human actions. Desertification begins by remov-
ing vegetation from the landscape (by grazing animals, or as a result of shifts in rainfall
patterns and a warming climate). When the vegetation is gone, it no longer anchors the
soil, which means the soil can be easily removed by wind or water erosion. Without soil
— which includes sediments, organic matter, water, and nutrients — there is no support
for future vegetation growth.
Desertification is most dramatic in regions that are already warm and are getting warm-
er. (Keep reading for some information on climate change.)
Creating Caverns