Weathering Flashcards
physical/mechanical weathering, definition
rocks being broken down w no chemical changes
main factor for weathering
temperature
how does physical weathering occur
rocks contract + expand w temp, causes stress, stress = breakdown of rock
exfoliation, definition
granite + inconsistent temp = rounded dome, layers flake off like onion
granular disintegration, definition
rocks break down grain by grain, this is a characteristic of a sedimentary rock w coarse texture
frost shattering, definition
when temp = below freezing, water freezes, expands, makes cracks widen, when temp rises, water melts, causes contraction, this action = repeated till rock shatters
joint cracking, definition
happens to rocks recently exposed to surface, pressure on rock = reduced, expands and cracks along weak points in rocks
chemical weathering, definition
breaking down of rocks by altering its chemical composition
most important components for chemical weathering, and what climate do they require to take place in?
water plus oxygen, take place in warm, moist, regions
oxidation, definition
oxygen outside + iron in rocks = iron oxide, which is red
carbonation, definition
carbon dioxide mixed w oxygen - forms acid which reacts w carbonates in the rock, acts as a solvent, happens in limestone and dolomite
hydration, definition
if water = evaporated from soil, salts crystallise, if salt absorbs water, causes swelling, breaks rock down.
biological weathering, definition
plants/animals break down rocks into sediments/soil
definition of weathering
breaking down of rock and soil, no movement of the material takes place
erosion definition
movement of soil, mud, rock + other particles
