The Valentian Series

Abstract

I. History of the Nomenclature of the Valentian Series. The term is now commonly adopted for the rocks which lie between the top of the Bala and the base of the Wenlock or Salopian. These rocks have a wide distribution in Wales and the Borders, the Lake District, and the South of Scotland, as well as in Ireland and on the continent of Europe. They exhibit great diversity of lithological and faunal characters and of thickness when traced from one district to another, and on this account their classification and correlation has always presented difficulty. Various classifications are in current use, but their relation one to the other is still ambiguous. It is with the hope of clearing up some of these difficulties that the following account of the historical growth of the nomenclature and the correlation of the rocks has been written. The earliest notice of these rocks in geological literature occurs in two early papers by Sir Roderick Murchison, which were read to the Geological Society of London in 1833 and 1834. In the earlier paper the rocks below the Old Red Sandstone in the western parts of Shropshire, Herefordshire, Radnorshire, Brecknockshire, and Carmarthenshire are arranged as follows, in descending order:— 1. Upper Ludlow Rock. 2. Wenlock Limestone. 3. Lower Ludlow Rock or Die Earth. 4. Shelly Sandstones. 5. Black Trilobitic Flagstone. 6. Red conglomerate, sandstone, and slaty schists. The Shelly Sandstones (No.