Sedimentary processes

Chemical weathering

Weathering of silicate and carbonate rocks produces a range of new minerals and solutions together with residual, resistant materials

Physical weathering

Breaks down rocks into smaller fragments

Insolation (physical)

The expansion and contraction of rock due to the Sun

Insolation works by...

Creates a thermal gradient between the interior and exterior of the rock which weakens bonds and creates stresses

Freeze thaw weathering (physical)

The repeated freezing and expanding, melting and contracting of ice

Hydrolysis (chemical)

Carbonic acid rain reacts with silicates such as feldspar

Hydrolysis produces...

Produces clay (kaolinate) and ions of potassium and silicon in solution

Carbonation (chemical)

CO2 reacts with rain water to form carbonic acid

Oxidation produces...

Haematite and carbonic acid

Oxidation

Particularly iron rich minerals incorporate oxygen atoms into their structure

Iron becomes a red colour during oxidation...

Due to rusting

Solution

Transports the products of chemical processes away

Biological weathering

Physical or chemical weathering caused by plants or animals.

How is limestone formed?

Calcium carbonate shell fragments pressed together to form rock over time

How is coal formed?

Forrmed from plant remains subject to high heat and pressure over millions of years

Beach characteristics (shape, sorting, size and why)

Angular, moderately sorted, larger material due to higher energy

Sand dune characteristics (sorting, size and why)

Very well sorted, fine grained material since transported by wind

River characteristics (sorting, size and why)

Moderately sorted, larger material due to higher energy

Glacier characteristics (sorting, size, processes and why)

Poorly sorted, larger material due to plucking, abrasion and higher energy

Rocks are composed of...

Composed of aggregates of minerals, pre existing rocks or fossils

Aggregates of minerals

Raw materials produced from natural sources and extracted from quarries

Examples of mineral aggregates

Crushed rock (limestone, igneous rock and sandstone), sand and gravel

Composition of sedimentary rocks

Clay, quartz, calcite and other minerals

Texture of sedimentary rocks

Fine, medium, coarse grains
Rounded, sub rounded, angular
Well, moderately, poorly sorted

Composition of igneous rocks

Felsic, intermediate, mafic, ultramafic

Texture of igneous rocks

Fine, medium, coarse crystals
Euhedral, subhedral, anhedral crystals
Equicrystalline, porphyritic

Composition of metamorphic rocks

Slaty cleavage, schistosity, gneissic banding

Texture of metamorphic rocks

Foliated or non foliated