OF THE EOCKS OP THE SOUTH OP lEELAND. 267 



IX. Belgian Sections. 



A recent visit to the valleys of the Meuse and Ourthe in Belgium, 

 following on a study of numerous maps and memoirs*, has enabled 

 me to obtain a clearer idea than I previously possessed of the Devo- 

 nian series of that country with a view to comparison with that of 

 North Devon and the south of Ireland. After observing the splen- 

 did sections along these rivers of the beds from the Carboniferous 

 Limestone down towards the base of the Devonian series, it was 

 impossible to come away without being impressed with the impor- 

 tance of the Devonian rocks amongst the formations of Northern 

 Europe, fully justifying Sir R. Murchison, Prof. Ferd. Eomer, and 

 other geologists in giving them a position second to none amongst 

 Continental groups t- The distinct infraposition of the Upper Devo- 

 nian beds to the Carboniferous is perfectly clear and indisputable 

 in the sections of the Meuse, north of Dinant, and in those of the 

 Ourthe, south of Liege. The beds are different from the Carboni- 

 ferous both in mineral character and order of succession ; so that it 

 is impossible to suppose they can be repetitions. At the same time 

 the beds themselves are wonderfully bent, flexured, and folded ; but 

 there is no difficulty in determining their position and relations to 

 each other when once the succession has been clearly made out. 



That the Devonian beds of Belgium are representative of those 

 of North Devon is abundantly clear as regards their palaeontology, 

 the main distinction in their composition being the greater predomi- 

 nance of limestones in the Belgian area, and of sedimentary beds in 

 Devonshire. 



It seems to me very difficult, if not impossible, to determine the 

 representative beds in Belgium and Devonshire, except in a few 

 cases. That the " Psammite du Condroz " is the equivalent of the 

 " Pickwell-down sandstone " has been recognized by Prof. De- 

 walque, and does not admit of a doubt. In Belgium, however, it 

 is in aU probability a marine formation, Spirifers and other fossils 

 occurring in the lower part ; and it is overlain by fossiliferous shales 

 (representing the " Lower Limestone Shale " of England), by which 

 it is separated from the Carboniferous Limestone. The " Calcaire 

 de Erasne," with Spirifera disjuncta, which underlies the " Psammite 

 du Condroz," is an important limestone formation in the Liege 

 district, though apparently represented only in South Devon. It is 

 considered by Prof, de Koninck to be a subordinate member of the 

 Upper Devonian group. The " Calcaire de Givet " is the most im- 

 portant limestone member of the series, and, as indicated by its 

 fossils, is the representative of the Ilfracombe and Plymouth Lime- 

 stones on the one hand, and of the Eifel Limestone on the other. 



* Dumont's Carte geologique de Belgique, maps and sections of the districts 

 of Dinant and Namur, issued by the government survey under M. le Directeur 

 Dupont. Sections and specimens, in the Museum of'Brussels, by MM. Dumont, 

 Gosselet, Dupont, and Mourlon ; together with memoirs by MM. Gosselet, De 

 Koninck, Dewalque, &c. &c. 



t I was unfortunate in not being able to examine the Lowest Devonian beds 

 with the attention I devoted to the Upper and Middle. 



I2 



