GEOL105 Lecture Notes - Lecture 8: Hydrolysis, Lichen, Calcite
Document Summary
Weathering is defined as the breakdown of bedrock near or at the surface (exposed to weather) Slow continual removal of material: soil formation, mass-wasting or landslides . Two ways to break down rock: 1) mechanically or physically, 2) chemically, also through biological activity, which can be physical, chemical or both. Rock disintegrates into smaller fragments: physically broken, does not change mineral compositions. Expands again when its warm (daytime) again layers peel away (scree) These spherical boulders formed directly from bedrock by the expansion- contraction process shown above (notice temperatures are in celsius). This location is a desert with large day/night temperature changes. The temperature falls below 0 degrees celsius. The water freezes and expands, making the crack bigger. Eventually after repeated freezing and thawing, the rock breaks off. Water works as a wedge or pry-bar, freeze-thaw by freeze-thaw cycle prying bedrock apart.
