Weathering and erosion - part 1.pdf

Weathering and erosion Weathering • The physical and chemical processes that break rocks down Physical weathering • Weathering can happen because of: • • • • • Temperature change Water and ice Crystallization of salts Wind Living plants Temperature • Solids expand when they are heated and con...

Weathering and erosion Weathering • The physical and chemical processes that break rocks down Physical weathering • Weathering can happen because of: • • • • • Temperature change Water and ice Crystallization of salts Wind Living plants Temperature • Solids expand when they are heated and contract when they are cooled. • The same happens with rocks except this can crack rocks Ice and water • Can split rocks by freezing water • As the ice expands it widens cracks in rocks Salts • As salts crystalise in rocks they weather them Glaciers • They are like frozen rivers of ice that move along valleys very slowly • As they move, the ice scrapes pieces off the surrounding rocks, forming valleys that are U shaped Water • Water running or washing over rock can also wear them away Wind • Fine particles of rock carried blast the rock surface Plants • Plants growing through rocks can split them Chemical weathering • Involves water and chemicals in the water and air reacting with the rock and changing it • E.g. dolerite reacting with Oxygen. The iron in it forms Rust and as it does it doesn’t hold the dolerite together acid • Acid rain which contains dissolved acids can dissolve the rock Erosion • Small particles of rock broken off by weathering can be carried away by water, wind and ice • The removal of rock particles is called erosion