Weathering

**Physical Weathering:**
– Disintegration of rocks without chemical change
– Breakdown into smaller fragments through processes like expansion and contraction
– Types include freeze-thaw weathering and thermal fracturing
– Pressure release can also cause weathering
– Often occurs hand in hand with chemical weathering

**Chemical Weathering:**
– Chemical reactions with water, oxygen, and carbon dioxide change rock composition
– Water converts primary minerals to secondary minerals via hydrolysis
– Oxygen oxidizes many minerals
– Mountain block uplift exposes new rock strata to weathering
– Chemical weathering changes original minerals into a new set closer to surface conditions

**Biological Weathering:**
– Lichens and mosses create a humid microenvironment on rock surfaces
– Lichens pry mineral grains loose from shale with hyphae
– Seedlings and plant roots exert physical pressure on rocks
– Living organisms contribute to both mechanical and chemical weathering
– Enhance physical and chemical breakdown of rock surfaces

**Weathering Effects:**
– Buildings made of stone, brick, or concrete are susceptible to weathering
– Natural weathering processes damage statues and monuments
– Acid rain accelerates weathering of buildings
– Design strategies can moderate the impact of environmental effects on buildings
– Concrete mixes with reduced water content minimize the impact of freeze-thaw cycles

**Soil Weathering and Formation:**
– Granitic rock weathers to clay minerals and iron oxides
– Well-weathered soils are depleted in calcium, sodium, and ferrous iron
– Basaltic rock weathers more easily due to fine grain size and volcanic glass presence
– Basalt weathers to clay minerals and aluminium hydroxides in tropical settings
– Soil formation requires between 100 and 1,000 years, resulting in various paleosol bedshttps://en.wikipedia.org/wiki/Weathering