Permian and Triassic rocks are widely distributed beneath the seas surrounding Scotland but have only limited, mostly basin-margin, exposures on land (Fig. 10.1). They occur on the coast of the Moray Firth near Elgin and Golspie, in several small basins in the south and southwest of Scotland, including Dumfriesshire, Ayrshire and the Isle of Arran, and in a series of small exposures along the western seaboard of Scotland from Kintyre, through Mull and Ardnamurchan, Skye and Raasay to the vicinity of Stornoway on the Isle of Lewis. Each of these areas will be described in the context of the adjacent, mostly offshore, basinal development. The widespread distribution of rocks of Permo-Triassic age is indicative of a former very extensive cover. The historical reasons for the offshore extent but limited onshore exposure of the Permo-Triassic sequences are outlined below.
Global sea level during the Permian and Triassic was generally fairly low (Vail et al. 1977), and Scotland was located far from the coast within the former Laurussian part of the megacontinent Pangaea (Fig. 10.2), thus onshore exposures of Permian and Triassic rocks are almost entirely the product of terrestrial sedimentation. Over parts of continental Europe, such conditions of deposition commenced during the Late Carboniferous.
Several (4-6) Late Permian (Zechstein) marine transgressions, with intervening evaporation almost to dryness, affected the North Sea area. No route can be found for marine flooding of the time equivalent Bakevellia Sea of the Irish Sea and Antrim (Smith & Taylor 1992; Jackson