Rocks (Keywords)

Rock cycle

A cycle describing the earths processes that causes types of rocks to be formed, changed, destroyed and recycled

Lithification

Sediments are compacted and cemented together to form rock.

(Cementation + Compaction)

Compaction

Sediments are squeezed together by the weight of above layers, including water.

Cementation

Water evaporates from dissolved minerals making crystals that glue sediments together.

Intrustive/Plutonic Rocks

Rocks formed beneath the surface.

Extrusive/Volcanic Rocks

Rocks formed on or near the surface.

Sediments

Loose, solid particles that come from weathered rocks, shells or organic material.

Cementation

When loose sediments are glued together by minerals in the spaces between grains.

Strata

Horizontal layers of limestone rock.

Thermal metamorphism

• Occurs when rocks are affected by heat supplied by magma moving deep in the earth’s crust or where it surfaces.

• Quartzite was formed in Wicklow via thermal metamorphism.

Regional metamorphism

• When rocks are changed by heat and pressure over large areas due to the earth’s plates.

• This is how gneiss is formed.