older Deposits of the North of Germany and Belgium. 271 



So far we have been explaining the views of Prof. Dumont by applying them 

 to lines of section which we personally examined. With very limited exceptions 

 we adopt his successive mineral groups ; and we think, beyond all shadow 

 of doubt, that he has (somewhat in the manner pointed out) determined their 

 true order of superposition, which we shall therefore assume at once as a mat- 

 ter proved. Had not his methods been so very different from those we com- 

 monly have recourse to in this country, we should not so long have dwelt upon 

 them ; and we can only further refer our readers to his published works. Our 

 next object must be to bring these several groups or systems into comparison 

 with their British equivalents ; and this must be done chiefly on the evidence of 

 fossils. 



Description of the successive Groups. 



1. We need not dwell on the carboniferous system of Belgium, because there are no doubts respecting 

 its relations. For the same reason we may pass over the upper limestone of the terrain anthraxifere, 

 as' it is the undoubted equivalent of the English carboniferous limestone. It may seem strange to an 

 English geologist, that this limestone should have been grouped in a system inferior to the carboniferous : 

 but in Belgium we have no beds of coal alternating with the limestone, and forming a passage into the 

 richer and higher part of the coal-field ; and the upper and lower limestones have so many analogies, 

 especially in lithological characters, that, with reference only to Belgium, we think this classification 

 by no means unnatural. It is hardly necessary for us to add, that, as English geologists, we should of 

 course strike off the upper limestone from the terrain anthraxifere, and group it with the carboniferous 

 system. 



2. The next descending group is the systeme quartzo-schisteux superieur, which we must describe 

 very briefly, as our limits allow of very few details. It is separable into two very distinct members, — 

 an upper and a lower. The upper division is chiefly characterized by an open-grained, yellowish sand- 

 stone (psammite de Condroz), sometimes passing into a hard grey micaceous flagstone, not unlike a coal- 

 measure flagstone. The yellowish beds are meagre to the touch, and are generally rather soft and earthy, 

 and have subordinate bands of greenish grey indurated shales or mudstones : among them also are rarely 

 found some bands of a rotten cellular psammite, with many casts of fossils, among which we at once 

 distinguish Terebratulce, three or four species of Spiriferce, and small investing corals. The higher 

 parts of this upper division are generally harder and thicker-bedded than the lower ; but on ap- 

 proaching the mountain limestone they are seen to alternate with courses of shale. The shales also 

 begin to alternate with beds of limestone ; and the two systems are thus linked together by a gradual 

 passage, showing that the deposits were absolutely continuous. A few obscure impressions of plants 

 are found in this upper division ; and its thickness in the neighbourhood of the Chateau d'Halloj' 

 may be about 1500 feet. As some of its fossils cannot be distinguished from those of the carboni- 

 ferous system, into which it forms a true passage ; and as it does not contain, as far as we know, a 

 single Ludlow rock fossil, it is impossible to consider it as older than the upper part of the old red 

 sandstone, and indeed it is very doubtful whether some English geologists would not arrange it with the 

 mountain limestone. 



The hwer division of this system (systeme quartzo-schisteux superieur) is also composed of alternating 

 beds of psammite, and of an indurated shale or earthy schist ; but the latter is more abundant than the 

 former ; and indeed this whole inferior group is characterized by the great quantity of greenish-grey, 



2 N 2 



