Here's a breakdown:
Physical Weathering:
* Frost wedging: Water seeps into cracks in the rock, freezes, expands, and puts pressure on the rock. This repeated freezing and thawing can cause the rock to break apart.
* Thermal expansion and contraction: Rocks expand when heated and contract when cooled. This repeated expansion and contraction can weaken the rock and cause it to break.
* Abrasion: Rocks can be broken down by friction from wind, water, or ice carrying other rocks and sediment.
* Exfoliation: Layers of rock peel away due to changes in pressure, like when an overlying layer of rock is removed by erosion.
Chemical Weathering:
* Dissolution: Some minerals in rocks dissolve in water, particularly acidic water.
* Oxidation: Iron in rocks reacts with oxygen, forming iron oxides (like rust) which weakens the rock.
* Hydrolysis: Water reacts with minerals in the rock, causing them to break down.
* Biological weathering: Plants and animals can contribute to weathering. Roots can grow into cracks in rocks and cause them to widen, while animals can burrow into the rock.
The specific processes that dominate in breaking down bedrock depend on factors like climate, rock type, and topography.
