Landscape Development - rock types create distinctive landscapes

What Happens when limestone is exposed on the surface

It is chemically weathered by carbonation and forms a karst landscape.

E.g. the Burren Co. Clare.

What did glacial erosion thought to remove

Soil that covered this surrounding area exposing limestone rock to carbonation.

Carbonation

• Chemical weathering process

• Rain absorbs CO2 through the atmosphere

• This becomes weak carbonic acid;

• slowly dissolves limestone both underground and surface.

Limestone

Sedimentary rock - jointed, layered.

Joints - vertical lines of weakness in limestone, they ae slowly enlarged by carbonation.

Overtime..

The joints get wider, deeper and form Grikes.

Clints

The slabs or rocks separated by grikes.

Clints and Grikes results

limestone pavement landscape

Igneous

Occurs when magma rises, cools and solidifies.

Extrusive/volcanic rock - when magma cools and hardens on the surface

e.g. basalt

Intrusive/plutonic rock - when magma cools and hardens with the crust

e.g. granite

Example of extrusive igneous rock

The Antrim-Derry Plateau

formed when the lava from a divergent plate boundary cooled quickly on the surface.

• 65MYA

• American ←→ Eurasian plates - lava split onto the mantle to the surface.

• Lava cooled

• formed igneous basalt rock.

The Giants Causeway

Part of the Antrim-Derry plateau

• 60,000 basalt columns

• lava cooled quickly in a river valley

• Large crystals formed as it cooled

• Once cooled the lava contracted

• It broke into hexagonal columns