V.—The Tectonic Evolution of the Midland Valley of Scotland

Abstract

I. INTRODUCTION: GENERAL GEOLOGY AND STRUCTURE The Midland Valley of Scotland comprises the great trough of Upper Palaeozoic rocks, some 50 miles in width, which extends south-westwards across the heart of the country from the Firths of Forth and Tay to the Firth of Clyde. It is bounded to north and south by parallel major dislocations, the Highland Boundary and Southern Uplands faults respectively, and represents an ancient rift valley or graben which was initiated as such during the Caledonian orogeny and subsequently functioned as a basin of deposition throughout Old Red Sandstone and Carboniferous times. Unlike the typical rift valleys of East Africa and the Rhine, however, the Central Scottish graben does not intersect a previously consolidated rigid table-land or shield, but lies wholly within, and trends parallel to, a contemporaneous orogenic belt (the Scottish Caledonian mountain system) and owes its initiation and development directly to the operation of the orogenic forces. It is a matter of considerable interest, therefore, to examine the tectonic rôle of the Midland Valley in the evolutionary history of the Scottish Caledonides, and the significance of the region in relation to the problems of graben in general. It must be emphasized that the present paper constitutes merely a first attempt to synthesize the available information, but it is hoped, nevertheless, that it may at least serve to indicate the limitations of our knowledge and so direct attention to the more fruitful lines for future research. General Geology and Structure .—The general geology of the Midland This 250-word extract was created in the absence of an abstract