Intrusive volcanic landforms

Dikes - part 1

1. Dykes - Formed when magma spreads through fractures and joints in the crust in a vertical manner; these weakness may have already existed before but grow and widen due to the pressure of the magma. They vary in size from a few cms to several ms.

Dykes - part 2

They tend to be more resilient than the surrounding rock and so are weathered and eroded far more slowly, often jutting our in the landscape when their surroundings have been worn away.

Sills - part 1

1. Sills - Formed when magma spreads through the fractures in the crust in a horizontal manner; true to the pressure they are able to form either Laccoliths or Lopoliths.

Sills - part 2

Laccoliths are formed when the magma is particularly viscous and so, unable to spread quickly, forces the overlying rocks to arch upwards. Lopoliths are formed under the same conditions, but instead the underlying rocks are forced downwards.

Batholiths - part 1

The largest type of pluton. They can be 29km deep and hundreds of km wide. These are formed in huge gaps or cavaties in the crust when magma wells up to fill empty space

Batholiths - part 2

Sometimes, it either pushes rock out of its path or melts them to make space. Eg, Leinster Batholith