carboniferous coal limestone
CONTINENTAL EUROPE. - As in Britain so on the Continent the Carboniferous system occupies many detached areas or basins--the result partly of original deposition, partly of denudation, and partly of the spread and overlap of more recent formations. There can be no doubt that the English Carboniferous Limestone once extended continuously eastward across the north of France, along the base of the Ardennes, through Belgium, and across the present valley of the Rhine into Westphalia, From the western headlands of Ireland this calcareous formation can thus be traced eastward for a distance of 750 English miles into the heart of Europe. It then begins to pass into a series of shales and sandstones, which no doubt represent the same proximity to shore as the similar strata in the north of England and Scotland. In Silesia, and still much further eastwards in central and southern Russia, representatives of the Carboniferous Limestone appear, but interstratified, as in Scotland, with coal-bearing strata. Traces of the same blending of marine and terrestrial conditions are foand also in the north of Spain. But over central France, and eastwards through Bohemia and Moravia into the region of the Carpathians, the Coal-measures rest directly upon the older formations, most commonly upon gneiss and other crystalline rocks. It would appear that these tracts had remained above water during the time of the Carboniferous Limestone, but were gradually depressed daring that of the Coal-measures.
In the north of France and Belgium the British type of the Carboniferous system is well shown. At the base lies a group of green, grey, and reddish shales and yellow sandstones, precisely similar in lithologieal character to parts of the Calciferous Sandstones of Scotland. They are well seen in some recent railway cuttings to the north of Boulogne, and also in the valley of the Meuse above Namur, lying upon the Psammites de Condroz or Upper Devonian beds. They are succeeded by the Carboniferous Limestone, which is subdivided into eight formations, having an aggregate thickness of 800 metres, and each characterized by its own assemblage cf fossils. The horizon of the Millstone Grit is marked by the occurrence of certain alum-schists. The Coal-measures of this area have been referred to in the article CoAL.2 The Saarbrack coal-field furnishes a good example of that type of the Carboniferous system where the lower marine series is absent. It lies unconformably on Devonian rocks, and attains a thickness of more than 10,000 feet. It is divided into the following groups of strata: - sandstones, clays, resting upon the great coal-bearing division, Abundant plants, with labyrinthodonts and insect remains.
Geinitz, drawing attention to the distribution of plants in the Saxon Coal-measures, remarks that a certain order can be observed in their appearance. lie divides the strata aecordingly into three zones, each marked by a characteristic assemblage of pfants, and he believes that the classification can be applied in other countries.
Lepiciodendron, Calamites Asterophyllites, and a Mw I rm.
with ,Sphenopteris distal's, Calaneitcs transiticwis, he.
The lowest of these zones (1) is compared by Geinitz with the Cubit, that is, the sandy, shaly, and coal-bearing representative il. the Carboniferous Limestone. To the cast of the Ehine valley, as already mentioned, the trite Carboniferous Limestone loses its normal character and assumes that of the Culm - a series of shales, sandstones, greywackes, and conglomerates, in which the abundant fauna of the limestone is reduced to a few mollusks (Productus antiquus, P. latissimus, P. soniretieulatus' Posidommipa Beek(ii, Gonialites vim. ieus, Orthoecras striatul um ,be .). The Positionomyn. particularly characterizes certain dark shales known as Eosidonia scldsts. About 50 species of plants have been obtained from the Cahn, typical species being Cala9nitcs transilienis, Sayehariu 1., itheimiana, Stiffmaria jicoides, ,Sphenopteris distalls, Cyclopteii, temcifolia. This flora bears a strong resemblance to that of the Calciferous Sandstones of Scotland.