Caledonian Structures in Britain

South of the Midland Valley

This volume deals with those sites selected as part of the Geological Conservation Review (GCR) within the southern British part of the Caledonides, that is, the paratectonic Caledonides - a Caledonian terrane without strong and pervasive deformation and metamorphism, such as occurred further north. This orogenic belt formed by long and complex processes of earth movements between 500 and 380 million years before the present (?late Cambrian to mid-Devonian times), and has been classic ground for geologists for two hundred years. It is perhaps no accident that James Hutton in 1795 chose to illustrate his geostrophic cycle (and unconformity) with three visually explicit examples of the deformation wrought on Lower Palaeozoic rocks by Caledonian events. The former Caledonian mountain chain, which can be seen today in fragmented pieces in Scandinavia, Britain and Ireland, and North America, was ultimately the result of the collision of two continental plates and the closure of a former ocean, Iapetus. Some of these fragments, including those in Scandinavia, southern Britain, and the Republic of Ireland and the Maritime Provinces of Canada, are thought to have lain on the south side of the ocean before collision: the rest of North America, northern Ireland, and Scotland are thought to have lain north of the former Iapetus.