FRACTURE (GEOLOGY)

A 'fracture' is any local separation or discontinuity plane in a geologic formation, such as a joint or a fault that divides the rock into two or more pieces. Fractures are commonly caused by stress exceeding the rock strength. Fractures can provide permeability for fluid movement, such as water or hydrocarbons. Highly fractured rocks can make good aquifers or hydrocarbon reservoirs, since they may possess both significant permeability and fracture porosity.
Fractures are generally produced by the action of natural stress on the rock, however they can also be created as a result of natural or man made hydraulic fracturing.