Weathering Flashcards

Flashcards about Weathering

Weathering

The weakening, breaking up, and disintegration of rocks that form the surface of the ground and lie exposed to the weather elements in situ.

In situ

A Latin phrase which simply means “in its original place” /”stationary.”

Mass wasting

Is the movement of regolith and other weathered material en masse due to the force of gravity.

Chemical weathering

The breaking down or decomposition of rocks as a result of various chemical processes and reactions altering the chemical components of the rock.

Oxidation

Occurs when rocks or more specifically certain minerals within the rocks are exposed to and react with oxygen in the air or water.

Hydration

Some types of rocks for example those that contain salt minerals have the capacity to absorb water into their structure causing them to swell and become susceptible to future breakdown.

Hydrolysis

Hydrogen ions in water react with minerals ions in the rock

Carbonation

This is when carbon dioxide dissolves with rain water to form carbonic acid.

Organic Weathering

Decomposing vegetation (humus) releases humic acid, which attacks calcium, magnesium and iron minerals within rocks.

Acid rain

Human and economic activities are realising more and more carbon dioxide into the atmosphere together with other chemicals such as sulphur dioxide and nitric oxide, which when dissolved into rainwater forms this.

Physical weathering

The disintegration of a rock into smaller particles by mechanical processes and without any changes in the chemical composition of the rock.

Exfoliation

Rocks expand when heated and contract when cooled much like all solid materials, causing outer layers of the rock to peel off like the rings of an onion

Frost shattering

It occurs in rocks that have crevices and joints and where there is limited vegetation cover and temperatures revolve fluctuate around 0°C; water freezes leading to breakdown

Salt crystallization

Saline (water containing salt) water enters pore spaces in rocks, and as it evaporates salt crystals are likely to form, exerting stress upon the rocks causing it to disintegrate.

Pressure release

Intrusive granite landforms such as batholiths are formed deep below the surface and under intense pressure due to the weight of the overlying overburden; the reduction in pressure causes fractures to develop especially on the top layers of the rock.

Inselbergs/Monadnocks

An isolated rock hill, knob, ridge, or small mountain that rises abruptly from a gently sloping or virtually level surrounding plain.

Ruwares/Dwalas/Whalebacks

A hill or rock which is dome shaped and rises several metres from the ground.

Tors/kopjes/castle kopjes

A small and isolated hill made of granite rock piles.

Limestone pavements

Flat areas of exposed limestone rocks where the pavement has joints that reach the surface, these joints may be widened by acid rain water, this process is called carbonation. The widening of the joints leaves deep incisions/gashes/fissures called grikes.