The area of this report is that part of the Irish Sea lying between the North Channel and St George's Channel. It is thought to contain rocks from the geological systems, ranging from Precambrian schists and gneisses to Cretaceous chalk and Paleogene basalts; many of these rocks subcrop beneath a locally thick cover of Quaternary sediments. Offshore, Carboniferous and Permo-Triassic strata dominate, and have considerable economic interest. The Carboniferous rocks contain coal; and are also the source for hydrocarbons. The Quaternary cover provides a large resource of aggregate. The report also looks at recent and present sedimentary processes at work in the Irish Sea.