Dykes and landscapes Dykes most frequently occur as igneous rocks which once were liquid magma that

Dykes and landscapes

Dykes most frequently occur as igneous rocks which once were liquid magma that intruded older rocks. Dykes form as sub-vertical to vertical linear sheet-like features and can be millimetres to kilometres wide.

Dykes can contribute to formation of interesting landscape features. For example, in above photograph, the dyke was more resistant to weathering and erosion than the rock it intruded, and so, it gave rise to a tall protruding wall known as the Breadknife, the Warrumbungle National Park. Whereas, in the photograph below, the dyke is less resistant to weathering and erosion, and so erosion of the dyke resulted in formation of a slot or a gully in the cliff near Kiama, south coast NSW.

Erosion of surface features (such as rocks) at different rates is referred to as differential erosion.