1855.] AUSTEN COAL MEASURES. 535 



from the valley of the Ruhr, by Aix-la-Chapelle, through the Ardennes 

 and the south of Belgium, by Liege, Namur, and Valenciennes, and 

 accompanied with the palaeozoic formations lying on its northern 

 flank ; the contour of the old coast-line being more or less clearly 

 evidenced by the lithological conditions of the conglomerates, grits, 

 sandstones, &c., of the littoral or deep-sea deposits. The existence 

 of this ridge to the westv^^ard is proved by the chalk axis of elevation 

 through Artois (passing to the north-vv^est at a considerable angle to 

 the eastern part of the ridge), and by the denudation of the Boulon- 

 nais and of the Weald of Kent and Sussex ; whilst further to the 

 west, at Frome, in Somerset, the identical series exposed in the Bou- 

 lonnais emerges again, in similar unconformable relations ; and Devon 

 and Cornwall, as already stated, supply evidence of the western ex- 

 tremity of this old ridge, which united the two great north and south 

 ranges of land, and formed an extensive gulf-like configuration of this 

 western European area in palaeozoic times. 



It was along the inner (southern and western) borders of this 

 somewhat semicircular indentation (open apparently to the north) 

 that the great Coal-formation had its origin. In other words, the 

 Rhenish and Belgian coal-beds are the remains of a succession of 

 fringing bands of dense vegetation occupying a continuous tract of 

 coast-line. Regarding these in connexion with the Midland and 

 Northern coal-measures of England, the extensive range of a vast 

 littoral band of swamps and forests becomes defined. 



The Carboniferous land must have had some considerable vertical 

 elevations, and a vast expanse of continuous horizontal surface at 

 very slight elevations above the sea-level. The coal, for by far the 

 most part, is the product of a vegetation which grew on the spot on 

 which it is now found. At the sera in question the central gneissic 

 plateau of France was a terrestrial area, with lakes and rivers, and 

 supporting a rich Coal- vegetation, the remains of which are preserved 

 in the original depressions in which they were accumulated. This 

 old land-surface was connected with another in the Spanish penin- 

 sula. Towards the Vosges, also, there was an extension of land, and 

 there we find two distinct levels of coal-growth surfaces. The Vosges, 

 the Schwartzwald, and the Odenwald then constituted a continuous 

 tract, and the Saarbruck coal, with its numerous reptiles, was formed 

 under lacustrine conditions. 



Crossing the Hundsriick and the Ardennes, we find the great 

 Belgian coal-field to present very different conditions. It takes its 

 part in the sequence of palaeozoic rocks, aud is formed of a series of 

 marine sedimentary strata, alternating almost indefinitely with terres- 

 trial surfaces. 



With regard to the Boulonnais coal-series, the author referred to 

 his former communication on the subject, which shows that it belongs 

 to the Mountain Limestone series, below the geological horizon of 

 the Franco-Belgian coal. This latter, or true coal-measure series, is 

 not presented in the Boulonnais denudation (which represents a part 

 of the old east and west ridge), but probably underlies the Oolitic 

 rocks in the neighbourhood of the Marquise district. 



