− | A trap consists of a geometric arrangement of permeable (reservoir) and less-permeable (seal) rocks which, when combined with the physical and chemical properties of subsurface fluids, can allow hydrocarbons to accumulate. | + | A trap consists of a geometric arrangement of permeable ([[reservoir]]) and less-permeable ([[seal]]) rocks which, when combined with the physical and chemical properties of subsurface fluids, can allow [[hydrocarbon]]s to accumulate. |