DEVONIAN SYSTEM

in 1829 Sir R. Murchison and A. Sedgwick applied the name ‘Devonian System’ to rocks of Cornwall, Devon, and Somerset, preyiously known as Old Red Sandstone. These rocks fall between the Silurian and Carboniferous periods, and consist of different colored sandstones, grits, limestones, and calcareous slates; three groups, the Lower, Middle, and Upper, all containing fo il remains, including corals, crinoids, crustaceans, cephalopods, and mollusca. Middle group has richest deposit, the fo ils being more abundant than in the arenaceous rocks - of Scotland, Wales, and Herts, with which they are supposed to be contemporaneous. D. rocks are found in other parts of the globe besides Devon and Cornwall, and Central Europe. They extend from the Adrennes into S. Belgium. Another group is cut through by the Rhine at Bingen, and yet another by the Moselle at Tréves. fortified seaport on H. shore of Tamar estuary, Devons hire, England; important naval and military station; owes importance to royal dockyard, founded by William III., 1689, formerly known as Plymouth Rock. Pop. 81,694. #.), town, port, near mouth of Mersey, Tasmania,