Weathering key terms

Unfinished

Weathering

The process by which exposed rocks are broken down

Scree

Angular sediment that collects at the foot of a mountain range or cliff

Freeze-thaw

Physical weathering- Caused by expansion of water as it freezes, exerting pressure on the rock as the process repeats

Salt crystallisation

Breakdown of rock by expansion and contraction of salt crystals due to fluctuating temperatures above and below 26 degress

Heating and cooling

Expansion and contraction of rock in deserts due to repeated heating and cooling between night and day

Solution

Some minerals in rock require no chemical reaction to be soluble eg rock salt

Chelation

Humus releases organic acids which attack certain minerals

Hydration

Water is absorbed into the crystal structure of the mineral within a rock. The water absorption allows the minerals to swell and creates stresses, water within the crystal structure causes chemical changes

Carbonation

Dissolving of rock by acid rain

Oxidation

Oxygen is dissolved in water, the dissolved oxygen forms oxides or hydroxides on contact with rocks and minerals, causing rust

Hydrolysis

Carbonic acids release H+ ions from water, which combine with some minerals in rock (feldspar) which releases Na, K, Mg. Minerals within the rock now disintegrate

Exfoliation

Pelling off of the top layer of rock

Wetting and drying

Expansion and contraction of rock due to addition and removal of rock

Denudation

Weathering and erosion working together causing landscapes to be worn down

Regolith

Weathering breaks down a rock surface to produce a pile of loose debris

Physical biological

Plant roots seeking out joints and bedding planes. Animals digging holes in rocks

Chemical biological

Humic acids, Bird droppings can be acidic

Aspect

Direction of a slope impacts temperature, south facing slopes are warmer in winter and will experience more freeze-thaw action

Relief

Gradient of slopes, steeper slopes with more exposure will weather faster

Desertification

The process of fertile land becoming desert