Devonian System

Collier's New Encyclopedia (1921)

a name in geology originally given to the rocks of Devonshi Devonshire and Cornwall, England. This name was proposed by Murchison and Sedgwick to replace the more characteristic and older term of Old Red Sandstone (a fresh water deposit), because the slaty and calciferous strata in Devonshire contain a much more copious and rich fossil fauna than the red arenaceous rocks of Scotland, Wales, and Herefordshire, with which they are believed to be contemporaneous. The fossils of the lacustrine Old Red Sandstone are chiefly fishes which have been classed as Ganoids. Professor Huxley approximates them to the Siluride; but investigations in progress in 1900, it is believed, will assign many of them to the lung fishes, reprein modern waters by Ceratodus sented and Lepidosiren, and others not represented in the waters of the modern world. The fossils of the marine Devonians are largely corals such as Favosites and Cyathophyllum, with brachiopod shells and skeletal parts of other organisms. The physical condition under which the marine sediments in Devonshire were deposited differed greatly from that which marked the accumulation of the Old Red Sandstone and has caused some doubts as to the correlation of the two sets of strata. British geologists retain both names, the Devonian System and Old Red Sandstone System; in the United States the term Devonian is used almost exclusively. The strata intermediate between the Silurian and Carboniferous consist of sandstones of different colors, carcareous are divided slates into, the limestones Lower,, Middle etc., They Upper Groups, all containing and in the middle division, corresponding fossils; practically to the Hamilton of New York organic remains are especially and include corals, crinoids, brachiopods abundant mollusks, and crustaceans. Devonian rocks occupy a large area in central Europe, as well as in the United States, eastern Canada, and Nova Scotia. In the United States they are found in New York and Pennsylvania, and include sand and limestone, used as building material, and are classed under the names of Oriskany, the oldest term, Corniferous or Upper Helderberg, Hamilton, and Chemung. Devonian rocks appear in some regions of the Appalachian Mountains. In the middle part of Michigan they surround the coal basin; and they are also found in Kentucky, Indiana, Ohio, Illinois, eastern Iowa, and Nevada. In Maine they are in a metamorphic condition. In the Upper Groups of the Devonian System there are carbonaceous shales, which by mutual distillation give much of the petroleum and natural gas found in the sandstones of Pennsylvania and eastern Ohio. DEVONPORT (before 1824 called PLYMOUTH DOCK), a parliamentary and municipal borough, maritime town, and naval arsenal, in the S. W. of Devonshire, England; on the E. shore of the estuary of the Tamar, two miles W. N. W. of Plymouth. It stands on high ground, and is separated from its suburbs of Stoke and Morice Town by the glacis of its fortifications, once important, but now dismantled. The streets are regular, and the footpaths of marble. Devonport is supplied with water from Dartmoor Dartmoor by a circuitous route of 30 miles. It owes its existence to the dockyard established here by William III. in 1689, and is one of the chief naval arsenals in Great Britain. Pop. about 85,000.