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
Figures & Tables
This 4th edition of The Geology of Scotland is edited by Dr Nigel Trewin of the Department of Geology and Petroleum Geology at the University of Aberdeen. The volume is greatly expanded from the previous edition with 34 authors contributing to 20 chapters.
A new format has been adopted to provide a different perspective on the geology of Scotland. A brief Introduction is followed by a chapter outlining some of the important historical aspects that in the 19th century placed Scottish geologists at the forefront of a new science.
Scotland is constructed from a number of terranes that finally combined in roughly their present positions prior to about 410 million years ago. Thus the geology of each terrane is described up to the time of amalgamation, providing chapters on the Southern Uplands, Midland Valley, Northern Highland, Grampian and Hebridean terranes. At the end of this section, a brief synthesis summarizes the events that resulted in the amalgamation of the various terranes into the present configuration.
Traditional practice is followed in the description of the Old Red Sandstone, Carboniferous, Permo-Trias, Jurassic, Cretaceous, Tertiary and Quaternary strata. A separate chapter covers Tertiary igneous rocks. An attempt is made to tell the story of the geological evolution of Scotland, rather than catalogue all areas and formations. Priority is given to the onshore geology, encouraging the reader to go into the field and visit some of the world-class geology on show in Scotland. The chapters are broadly-based, attempting to integrate the sedimentary and igneous histories, and summarize changes in palaeogeography and palaeoenvironments.
Economic aspects are covered with chapters on Metalliferous Minerals, Bulk Resources, Coal and Hydrocarbons. A new departure is a chapter on aspects of Environmental Geology and sustainability.
Additionally, this publication contains a colour section of 32 plates, illustrating aspects of Scottish Geology, as well as a coloured geological map of Scotland.