Basin - a large, natural depression on the Earth’s surface in which sediments, generally brought by water, accumulate.
A depression in the crust of the Earth, caused by plate tectonic activity and subsidence, in which sediments accumulate.
Sedimentary basins vary from bowl-shaped to elongated troughs.
Basins can be bounded by faults.
Rift basins are commonly symmetrical, basins along continental margins tend to be asymmetrical.
If rich hydrocarbon source rocks occur in combination with appropriate depth and duration of burial, then a petroleum system can develop within the basin.
Most basins contain some amount of shale, thus providing opportunities for shale gas exploration and production.