Weathering: physical, chemical, and biological

Frost action works when water enters cracks, freezes, expands, and breaks rock. For exams, repeated freezing and thawing is the key clue.

Carbon dioxide dissolves in water to form carbonic acid, which dissolves limestone. In exams, connect limestone with carbonation.

Chemical weathering needs both water and heat for faster reactions. In exams, link hot humid climate with intense chemical weathering.

Different minerals expand and contract at different rates, so grains loosen. In exams, mineral heterogeneity is the base of granular disintegration.

Root growth widens cracks mechanically and may also release chemicals. In exams, remember both root pressure and acidic secretions.

Evaporation forms salt crystals, and their growth pressure breaks rocks. In exams, identify salt and evaporation together.

In hydration, minerals include water in their structure, causing expansion and weakness. In exams, expansion is the key clue for hydration.

Iron bearing minerals react with oxygen to form reddish brown oxides. In exams, reddish brown colour indicates oxidation.

When overlying pressure is removed, rock expands and may peel off in layers. In exams, link unloading with sheet peeling.

In hydrolysis, water chemically reacts with minerals and changes their structure. In exams, remember its role in soil formation.

Weathering generally breaks or alters material in place. In exams, transport of material indicates erosion.

Corners expose more surface, so weathering is faster there and blocks become rounded. In exams, edges and corners are the main clue.

Breaking creates smaller particles with more exposed surface area. In exams, larger surface area means faster chemical weathering.

In solution, water carries away soluble substances. In exams, salts and gypsum are examples of soluble minerals.

Minerals differ in hardness and chemical stability, so weathering is unequal. In exams, uneven surfaces indicate different resistance.

In moist soil, roots and microbes produce organic acids that alter minerals. In exams, vegetation and moisture indicate combined weathering.

Day heat and night cooling cause expansion and contraction in minerals. In exams, high daily temperature range links to physical weathering.

Joints and cracks provide pathways for water and air. In exams, more cracks mean higher weathering potential.

Feldspar changing into clay minerals is chemical alteration by water. In exams, feldspar to clay indicates hydrolysis.

Cold and dryness reduce chemical reactions and water availability. In exams, cold dry climate means slow chemical weathering.

Reaction with oxygen forms iron oxides that are reddish brown. In exams, rust like colour indicates oxidation.

Regolith is the layer of broken and altered material over bedrock. In exams, loose material formed in place indicates regolith.

Acids produced by organisms can chemically alter minerals. In exams, organisms plus acids point to biochemical weathering.

Carbonic acid rich water dissolves limestone and creates underground cavities. In exams, connect caves and limestone with karst processes.

Frost action breaks rock without necessarily changing mineral structure. In exams, breaking is physical and composition change is chemical.