Dikes are tabular or sheet-like bodies of magma that cut through and across the layering of adjacent rocks. They form when magma rises into an existing fracture, or creates a new crack by forcing its way through existing rock, and then solidifies.

How are Dyke formed?

When molten magma flows upward through near-vertical cracks (faults or joints) toward the surface and cools, dykes are formed. Dykes are sheet-like igneous intrusions that cut across any layers in the rock they intrude.

Are dikes older than sills?

Compared to the rock that they intrude on or cut, dykes and sills are often slimmer or less thick. They are also considered wider and younger in age compared to their surrounding rocks.