232 Professor Sedgwick and Mr. Murchison on the 



The beds which rise from beneath this limestone and occupy the tract near Ton- 

 nesheide, are highly inclined, dark-coloured shales, in parts psammitic, in parts 

 calcareous ; and these, occupying a very considerable thickness, are interposed be- 

 tween the carboniferous limestone, properly so called, and another inferior lime- 

 stone to which we shall soon advert. We detected some few obscure fossils in 

 these shales beneath the limestone as well as in those above it, but not in such 

 number or preservation as to enable us to draw any conclusions from them. 



By inspection of the map (PL XXIV.) it will be seen that, according to our views, 

 the carboniferous limestone which thus gradually changes its character in its east- 

 ward course from Ratingen, is cut off in the valley of Regrath, north of Tonnes- 

 heide. We have indeed fully satisfied ourselves by two visits, after an interval 

 of some wrecks, that it is not curved round to form a part of the limestone of Mett- 

 mann and Elberfeldt, which we proved to be an inferior member of the series ; 

 but is distinctly separated therefrom by the shales and psammites above mentioned, 

 which underlie it, and occupy a superficial extent of several miles*. 



The upper calcareous zone, which we are now considering, is not clearly traceable 

 at the surface through a certain distance eastward of the spot where it is cut off. 

 In the great flexure of the coal-field to the north-east of Elberfeldt, the lower car- 

 boniferous strata are thrown about in great confusion : but in proceeding towards 

 the eastern termination of the coal-field, where the escarpments become high and 

 the longitudinal gorges deep, we are presented with a succession of calcareous 

 strata which we regard as the undoubted equivalents of the carboniferous lime- 

 stone ; for they maintain precisely the same relations to the overlying and under- 

 lying strata which may be followed upon the strike. These calcareous beds, 

 rising from beneath the group of shale and sandstone before described, are asso- 

 ciated with chert and flinty slate, and thus far resemble the limestone near Velbert. 

 In some cases indeed the flinty slate so predominates, that the bands are better 

 designated as " kiesel schiefer " than as limestone : but here and there the calca- 

 reous matter appears in considerable force ; no longer, however, in thick, but in 

 thin, flat strata, occasionally passing into flagstone. 



In the quarries near Schelke there is a passage downwards from shattery beds 

 of sandy shale, with impressions of plants and thin courses of impure limestone, 

 into other schists and rather thicker bands of encrinite limestone, with layers of 

 " kiesel schiefer"; and these are repeated in several alternations. 



At a spot near Hemer, east of Iserlohn, and on the banks of the river Ohse, the 

 limestone and " kiesel schiefer " beds are of a similar structure, and are still more 

 expanded: and thence to the E.N.E. the same bands can be followed throughout 



* See the alteration in PI. XXIV. of Von Dechen's map by the insertion of two distinct limestones. 



