Despite its small size, the UK mainland and islands have a unique geological heritage that encompasses much of the preserved geological history of planet Earth, from the ancient, 2.5 billion year-old Archean gneisses of north-west Scotland and the Hebrides to the unconsolidated deposits of the Quaternary period, the last glacial deposits of which formed a mere 10 000 years ago.  The Old Red Sandstone is of particular interest in representing a period from about 415 to 355 million years ago when the amalgamation of the continental plates of East Avalonia, Laurentia and Baltica resulted in a new continent (the Old Red continent) and a mountain chain that extended from what is now Scandinavia through Scotland to the Catskill Mountains of America.  Erosion of the mountain belt produced the sediments of the Old Red Sandstone, deposited in the tropics south of the Equator in a semi-arid climate.

 

The oldest Old Red Sandstone is of Wenlock age, found in the Midland Valley of Scotland.  Three major depositional basins formed, all controlled to a greater or less extent by NE-trending transcurrent faults.  The Orcadian Basin of the Orkneys, Shetlands and northern mainland Scotland is one of the world's classic lacustrine successions, with stacked cycles of lake and lake margin sediment and a well-preserved fossil fish fauna.  The Midland Valley of Scotland contains thick successions of Early Devonian conglomerates and finer alluvial sediments, deposited in discrete sub-basins which opened and closed in a transcurrrent strike-slip regime.  The Anglo-Welsh Basin is renowned for its early fossil fishes and vascular plant remains.  Between the major basins are smaller ones, such as the Turriff Basin and the internationally famous Rhynie Basin in north-east Scotland, the Scottish Border Basin in the Solway–Northumberland region, and the Mell Fell Trough in the southern Lake District.

 

Scientific study of the Old Red Sandstone is as old as the study of geology itself, commencing with the classic observations of James Hutton at the Old Red Sandstone unconformities at Siccar Point, Jedburgh and North Newton, Arran over 200 years ago.  The fossil fishes of the Old Red Sandstone attracted Victorian collectors to its outcrops.  In more recent times, major advances have been made in the knowledge of the evolution of the Old Red Sandstone basins, the sedimentation and provenance of the deposits filling them, and the climate and palaeogeography of the Old Red Sandstone continent.

 

The Old Red Sandstone holds the evidence of an extraordinary period of the planet's history, when the vertebrates developed, flourished in the seas and rivers, and emerged on to the land, where the first vascular plants took root and the first arthropods crawled, breathed air and took wing.  The red colour which gives the Old Red Sandstone its special appeal is also the cause of a general dearth of fossils that geologists require to correlate and date rock successions.  The semi-arid tropical climate provided not only a harsh habitat for the biota but also poor preservation potential of their remains in the terrestrial sediments.  However, spore assemblages in grey or green strata continue to add resolution to the correlation of the successions, building on a broad framework provided by the evolution of the fishes.

 

The 70 sites detailed in this book, together with Old Red Sandstone GCR sites described in the volumes on Silurian stratigraphy, fossil fishes and Palaeozoic palaeobotany, provide a rich treasure of geological data that has enriched the study of geology in the past and will continue to provide exciting opportunities to researchers of the future. The book presents an audit of the best current Old Red Sandstone sites in Britain and will be a valuable reference work for stratigraphers, sedimentologists and palaeontologists.