How the Landscape Changes Due to Weathering and Erosion

Weathering and erosion are similar processes that occur over time, impacting the nature and appearance of landscapes. The two processes both affect rocks. Erosion is defined by the movement of air, water, or ice on rock formations, or on the force of gravity on rocks as in landslides. On the other hand, weathering simply breaks down or even chemically changes the composition of rocks without necessarily moving them. Weathering and erosion often occur together in the same place, leading to dramatic textures in the landscape.

There are two basic types of weathering: chemical and mechanical. Chemical weathering can be caused by things like coming into contact with acid in precipitation (acid rain), or due to airborne chemicals like carbon dioxide. The chemical reactions that take place inside plants as they extract nutrients from surrounding soils can also cause chemical weathering. Flowing water might introduce minerals that alter the chemical composition of rocks. The resulting chemical reactions in the rock cause it to change color or shape ("What's the Difference Between Weathering and Erosion?" n.d.). The formation of stalagmites and stalactites in caves is often related to chemical weathering ("What's the Difference Between Weathering and Erosion?" n.d.). Therefore, some forms of weathering create visually stunning results in a local landscape.

Mechanical weathering does not change the chemical makeup of the rocks but simply breaks down large chunks into smaller pieces due to any number of mechanical forces. For example, a tree's roots sometimes become powerful enough to render rock. Ice and frost can also cause mechanical weathering, as can be seen in human structures like asphalt roads. Even animals or insects can cause mechanical weathering as over time, they burrow into rock or tread over the same areas repeatedly. Heat or extreme swings in temperature can also cause mechanical weathering, as can wind and water. Mechanical weathering can be seen throughout desert areas, through the hollowing out of rocks or the transformation of rocks into unique shapes.

Typically, running water like that in rivers or streams is attributed to erosion rather than weathering but water actually causes both of these phenomena. Running water can break apart rock, as well as carry rocks from one place to another. Thus, water is responsible for both weathering and erosion. Erosion always entails the shifting of rock from one place to another. Natural rock arches and other striking geological formations in the landscape are usually formed from patterns of erosion, and sometimes both weathering and erosion is observable in the same spot as in the American southwest. Chunks of boulders may still be visible mere feet from where they fell, a clear sign of weathering, whereas the impressive hoodoo rock formations bear the stamp of erosion. Likewise, coastal regions display both weathering and erosion with the presence of sands and pebbles as well as vanishing shorelines.