(also called physical weathering) the breaking down of rocks by physical processes including temperature extremes, ice, water, and the activities of living things (biological weathering).
the mechanical weathering process in which water in the cracks of rocks freezes and expands, widening the cracks.
the breaking down of rocks by chemical processes. The reactions change the chemical structure of the minerals, producing an entirely new mineral.
(the most common form of chemical weathering) the breaking down of a compound by a chemical reaction with water. During hydrolysis, water dissolves minerals, which drain into lower layers of rock and soil, causing the minerals to concentrate into mineral ore deposits below the Earth's surface.
the result of sulfur dioxide, nitrogen oxides, and carbon dioxide reacting in the atmosphere with water and returning to the Earth as rain, fog, snow, sleet, or dew.
the process in which carbonic acid reacts chemically with other substances. The process can form underground caverns, stalactites, and stalagmites.
a chemical change in which a substance combines with oxygen. Example--iron (Fe) combines with oxygen (O) to form rust (Fe2O3). (the 2 and 3 should be subscripts)
the rapid downhill movement of a large amount of rock and soil. Landslides can be triggered by earthquakes, volcanic eruptions, spring thaws, or heavy rains.
a large block of soil and rock that slides downhill along a curved slope, forcing the rock mass to tilt backward.
mushroom-shaped rocks that form when sand particles eat away at the rock's bases. The sand particles are too heavy to reach the top of the rock, so the top does not get worn away.
water—usually from precipitation—that flows over the land; it is a constant source of erosion because it washes away particle of silt and soil. Note--because of gravity, water always flows to the lowest point.
an area of land that drains into a particular river system. For example, the Chesapeake Watershed includes Delaware, the District of Columbia, Maryland, New York, Pennsylvania, Virginia, and West Virginia. All of these states have land that sends water into the Chesapeake Bay.
a flat area along a river formed by sediments deposited when the river overflows, usually providing rich soil for farming.
Dams & Levees
built to control floods; dams are concrete structures built on a river to regulate its flow, while levees are made of an earthwork construction built up to stop water from flowing in a specific direction. The protection of a levee is temporary, and as rivers deposit more sediment, the levee must be made higher.
a large mass of moving ice. (An iceberg is a large floating mass of ice that has detached from a glacier and has been carried out to sea.)