The account of the Old Red Sandstone (ORS) given by Wally Mykura (1991) in the third edition of this book remains an authoritative account containing many details which will not be repeated here. Wally Mykura wrote at a time of active controversy concerning the relation of the Grampian Block to Devonian successions south of the Highland Boundary Fault. His untimely death robbed him of the opportunity to discuss problems which have been reconciled to some extent by recent work and revision of absolute ages for the Devonian (Tucker et al. 1998).
The chapter title follows tradition, recognizing that both the base and the top of the Devonian cannot generally be defined in Scotland. The Stonehaven Group of ORS facies is now thought to be as old as the Mid-Silurian (Marshall 1991) and the top of the Upper ORS passes conformably up into Carboniferous strata. The term Old Red Sandstone (discussion in Waterston 1965) was originally derived from the ‘Oelter rother Sandstein’ of Werner, and was applied to the Permian red sandstones of Germany. Phillips (1818) used ORS in its present sense, and Murchison (1839) considered it should be regarded as a system. However, it was Sedgwick & Murchison (1839) who established the Devonian system for marine strata in SW England and included the ORS within the Devonian. Old Red Sandstone is now used as a facies term and, whilst the rocks are mostly of Devonian age, there are notable exceptions.
The distribution of ORS strata (Fig. 8.1) shows
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.