Erosion
earth's surface at one location and moved to another. Erosion changes the landscape by wearing
down mountains, filling in valleys, and making rivers appear and disappear. It is usually a slow
and gradual process that occurs over thousands or millions of years. But erosion can be speeded
up by such human activities as farming and mining. Erosion begins with a process called
weathering; in this process, environmental factors break rock and soil into smaller pieces, and
loosen them from the earth's surface.
When the wind whips up a dust storm that stings our eyes, its ability to move sand is very clear. But the most powerful erosive force on the earth is not wind but water, which causes erosion in its solid form of ice and as a liquid. Water in its liquid form causes erosion in many ways. Streams from tiny creeks to huge rivers carry tons of eroded soil and rocks every year. The size of eroded materials a stream can carry depends on the speed of the stream, and the turbulence or roughness of the water; a fast turbulent stream can carry large rocks, while a slow gently flowing stream carries only particles of sand and clay.
There are many different kinds of erosion such as beach erosion which is a serious problem that impacts many beaches today on Prince Edward Island. Waves that are constantly hitting the land are carrying the sand away with them out to sea. Shores are decreasing in size over years, and have caused many problems with shore side building and plant and animal life. Many efforts with plants have been made to stop erosion but they are very expensive, and are not always successful. |
Not all rock or soil react the same to the forces of erosion; hard rock that contains many cracks
may wear away faster than softer rock because the cracks can cause big chunks of the rock to
break. Soft rock will lose just tiny bits at a time. Most soils erode more quickly than rocks,
since soil is made of smaller particles that are more easily washed or worn away.