A constructive force creates or builds something on the earth. For instance, volcanoes are built up by constructive tectonic plate movement. Destructive forces like tornadoes and tsunamis tear down or wear away parts of the earth.
Tornadoes, hurricanes, volcanoes, tsunamis, and earthquakes are all examples of destructive forces. The Grand Canyon is a result of destructive force. It was carved by water, which is one of the three agents of erosion. Erosion is a natural destructive process in which rock, soil or sediment is displaced or worn away. The other two agents of erosion are wind and ice. Ice erodes in the form of glaciers, forming valleys, and moraines. The third agent of erosion, wind, carries grains of sand that wear away at rocks.
Destructive forces can also be constructive. For example, as wind carries sand away from one region, it moves it to another and constructs sand dunes. Likewise, water forms deltas by depositing sediment at the mouth of a body of water.
The movement of tectonic plates can be constructive, forming volcanoes as plates converge or diverge. Iceland was formed, for example, by moving plates. Volcanoes are a destructive force because their eruptions destroy trees and other landmarks, but the magma they produce can be constructive as it dries on land to form mountains. Tectonic plate movement can cause earthquakes, which is another example of a destructive force that breaks apart land. Often, earthquakes and volcanic eruptions occur simultaneously as the result of plate tectonics.