Rocks found on the surface of the Earth undergo a process over time call weathering. Weathering is the breaking down of rock material. There are two main types of weathering: physical and weathering. Physical, or mechanical, weathering happens when rock is broken through the force of another substance on the rock such as ice, running water, wind, or plant growth. Chemical weathering occurs when reactions between rock and another substance dissolve the rock, causing parts of it to fall away.
Here are some examples of physical and chemical weathering of rocks.
Physical Weather Examples
Water movement is a major force in physical weathering. The persistent crash of waves against rocks causes physical weathering.
When water seeps into rocks and freezes, it expands and causes the rock to crack.
These mushroom-shaped rock pinnacles in Goblin State Park, Utah are formed by wind weathering the sandstone.
Roots from plants grow into rocks, cracking the rocks and causing weathering.
The honeycomb weathering seen in this photo from Utah is likely caused by physical weathering.
Chemical Weathering Examples
Chemical weathering can been seen in this photo of Blue Basin located in the John Day National Monument in Oregon. The green color of the claystone is from by chemical weathering of a mineral called celadonite.
Chemical weathering is, in part, responsible for the colorful oxidation of metals such as mica, iron, and manganese at Artist’s Palette in Death Valley.