A fracture is any local separation or discontinuity, such as a joint or a fault that divides into two or more pieces. A fracture will sometimes form a deep fissure or crevice. Fractures are commonly caused by stress exceeding strength. Fractures can provide permeability for fluid movement, such as water or hydrocarbons. When highly fractured we make good aquifers or reservoirs, since we may possess both significant permeability and fracture porosity.

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