Dike (geology) - Sedimentary Dikes

Sedimentary Dikes

Sedimentary dikes or clastic dikes are vertical bodies of sedimentary rock that cut off other rock layers. They can form in two ways:

• When a shallow unconsolidated sediment is composed of alternating coarse grained and impermeable clay layers the fluid pressure inside the coarser layers may reach a critical value due to lithostatic overburden. Driven by the fluid pressure the sediment breaks through overlying layers and forms a dike.
• When a soil is under permafrost conditions the pore water is totally frozen. When cracks are formed in such rocks, they may fill up with sediments that fall in from above. The result is a vertical body of sediment that cuts through horizontal layers: a dike.