The sedimentary basins of Britain and Ireland are numerous, occurring beneath both the land surface of these islands and the surrounding seas.
Sedimentary basins (not to be confused with drainage basins) have operated in this region over much of geological time from the Precambrian to the present day, typically accepting sediment from neighbouring areas where erosion is taking place, over timescales variously from millions to hundreds of millions of years.
They may be referred to simply as basins or else as troughs, grabens or half-grabens, according to their mode of formation and morphology.