Weathering

Physical Weathering: Disintegration of rocks without chemical change Breakdown into smaller fragments through processes like expansion and contraction Types include freezethaw 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 freezethaw cycles Soil Weathering and Formation: Granitic rock weathers to clay minerals and iron oxides Wellweathered 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 beds