Geology Reference
In-Depth Information
Human societies need water for many reasons, including for drinking, washing, and sup-
porting industry. Most of the earth's fresh water is stored underground as groundwater
in natural geologic storage tanks called
aquifers.
Demand for water by growing popula-
tions is exceeding the ability of the earth's natural water cycle to replenish it. The result
is that underground aquifers can be emptied, leaving cavernous open spaces under-
ground. With empty spaces below, the surface becomes less stable and can collapse in-
ward, creating a sinkhole.
The caving in of empty aquifers is a particular problem in regions that combine large
population growth and development with high demand for freshwater resources, such
as China, India, Pakistan, and California.
Transporting Earth Materials
Humans are constantly moving dirt and rocks around the earth's surface. Previously the
transportation of sediments relied on wind, water, or ice. But humans and technology
have dramatically changed the size and amount of earth materials that can be transpor-
ted from one place to another.
Boulders, gravel, and sand are mined for use in industry and landscaping. Before con-
structing a new building, the land may be leveled by removing or adding rocks and sedi-
ments to the site. The use of trucks, trains, and bulldozers has resulted in the transport
of tons of earth materials every day!
Changing the Climate
One of the biggest ways humans act as geologic agents is by affecting the global climate.
The earth's atmosphere and the gas and water that circulate through it come into direct
contact with (and change the surface of) the earth in many ways. Humans burn fossil
fuels such as coal and oil for energy, releasing carbon dioxide gas into the atmosphere.
Carbon dioxide and other greenhouse gases insulate the earth from the sun's harmful ra-
diation but also trap heat that would otherwise leave earth and radiate into the uni-
verse. Here, I briefly list some of the effects that modern climate change is having on the
earth's geologic system:
Increasing chemical erosion:
Adding carbon dioxide gas to the atmosphere
through the burning of fossil fuels (such as coal and oil) increases the rates of
chemical weathering. The interaction of carbon dioxide with exposed and uplifted
