Mechanical weathering is the erosion of rock caused by physical processes. Extreme temperature changes and constant exposure to water or air are common causes of mechanical weathering.
Mechanical weathering causes rocks to break apart into smaller particles known as sediment. One type of mechanical weathering is known as frost wedging, which occurs when water that fills cracks in rock formations freezes, causing the rock to expand and break apart.
Another type, thermal fracturing, happens when rapid temperature changes affect the expansion and contraction of the rocks' minerals at different rates, causing them to weaken.
Exfoliation, a third form of mechanical weathering, occurs when deep rocks become exposed to the elements, causing pressure changes that may lead to cracks in the rocks.