older Deposits of the North of Germany and Belgium. 241 



masses of porphyry run along like great ribs parallel to the successive sedimen- 

 tary deposits*. (See woodcut 2, p. 239.) 



Calcareous Rocks near Bensberg, Sfc. (Map, PI. XXIV. and PI. XXIII. Section 5.) 



Under this name we include a series of calcareous deposits which are first seen 

 on the south side of the road leading from Cologne to Bensberg (near the bottom 

 of the hill on which the latter place stands), and extend thence three or four 

 miles in a direction about N.N. W. to the neighbourhood of PafFrath. This range, 

 indicated by a series of open quarries, is not along the strike of the beds, but 

 nearly transverse to it ; for the several calcareous masses, where they are distinctly 

 stratified, strike (like all the older strata of the neighbouring country) about 

 E.N.E. 



The relations of these remarkable calcareous beds are very obscure ; as they 

 appear only here and there in low ground, and are partially overlaid by the 

 tertiary deposits which skirt the valley of the Rhine and form a breast-work 

 to the neighbouring hills. That they are superior to the Bensberg ridge of grau- 

 wacke cannot, how^ever, admit of a shadow of doubt, as their fossils link them 

 with the great "Westphalian limestone. They must therefore have been brought 

 into their present position by one of those great flexures which have so deranged the 

 positions of the mineral masses in the Rhenish provinces, and of which we have 

 some indications in the dips presented by the strata of the neighbouring hills. It 

 is also clear that they took their present position long before the existence of the 

 valley of the Rhine, or of any of the bordering tertiary deposits of brown coal and 

 sand. 



The beds near the Bensberg road are ill exposed, but abound in fossils. Cross- 

 ing, however, to the north, we meet with several quarries, having nearly the same 

 fossils, of which the beds exhibit a steady dip of more than 30° to a point about 

 S.E. by E. These may be called the Refrath series, and evidently belong to the same 



* Our friend M. Von Dechen has put into our hands a beautifully coloured geological map of the 

 Rhenish provinces, on a very large scale, in which he distinguishes the igneous rocks at Bruchhausen, 

 and throughout the tract around Olpe, as the common or red quartziferous felspar porphyry ; those of 

 Meschede, Brilon, Messinghausen, &c., as Labrador and Olikoglas porphyry. The latter rock displays 

 its intrusive origin by throwing off the beds near Bredelar to the north. The oxide of iron forms a 

 crust round the surfaces of these intrusive rocks, as in Nassau. In the country to the south of Brilon, 

 extending to Wittenberg (which we did not visit), M. Von Dechen has laid down nine parallel bands of 

 hypersthene rock, which are followed on the north side by three parallel lead veins, the whole being 

 coincident with the strike of the strata. M. Von Dechen and M. Erbreich have also pointed out the 



singular fact of the persistent dip to the south, to which we have already adverted (See account of the 



map which accompanies this memoir.) 



