242 Professor Sedgwick and Mr. Murchison on the 



formation as the Bensberg. Their fossils present close analogies to those at the base 

 of the great Westphalian limestone, and perhaps still closer to those in the lowest 

 division of the Eifel limestone to be described in the following part of this commu- 

 nication, {i.e. beds of passage into the Silurian system). Beyond the Refrath series 

 there is an interruption of nearly two miles ; after which a series of thin-bedded 

 limestones, with precisely the same strike and dip as before, break out in the quar- 

 ries. These beds (which may be called the Gladbach series) are several hundred 

 feet in thickness, and contain very few traces of fossils. 



This last group is succeeded to the N.N.W. (and apparently underlaid) by a 

 series of beds forming the quarries of Paffrath and Hand, which are of very com- 

 plicated structure, and contain innumerable organic remains occasionally in a state 

 of beautiful preservation. The fossils of this Paffrath group are celebrated among 

 German collectors ; and by the help of our friend Monsieur de Verneuil, who 

 possesses a fine series of them, we are enabled to subjoin a most instructive list 

 of species illustrated by figures. It is enough for us to state in this place, that the 

 group of most characteristic fossils is identical with that of the great limestones 

 of Westphalia and the Eifel. 



Were we to decide by the mere evidence of the sections, we must place the Paff- 

 rath group as the lowest, and the Refrath and Bensberg group as the highest portion 

 of the whole calcareous series above described. This arrangement is, however, 

 contradicted by the analogous sections of Westphalia, and we may add also, by 

 the sections of Belgium and the Eifel ; and we are constrained to admit, that the 

 vast flexure which twisted a portion of the great Westphalian limestone into the 

 valley of the Rhine, at the same time reversed the original position of its several 

 beds. 



Assuming this reversed position, we may therefore commence a descending 

 section near the Hand, and connect it through the intervening quarries with the 

 lower groups of Refrath. It is impossible for us to enter on full details ; but the 

 following sketch of the sections may serve to convey a general notion of the very 

 singular formation of limestone we are describing. 



General descending section. 



Paffrath group. — 1. Thick, irregular, cellular beds of dark bluish limestone with partings of dark 

 blue carbonaceous shale, with casts of Gi/pidium, Strigocephalus, and many corals (Hand quarry). 



2. A little lower in the series (at Gronau), calcareous shales with concretions of limestone full of 



corals, which are readily separable from their matrix. With the marls are associated many earthy, 

 pulverulent, yellow beds, like earthy magnesian limestone. Besides the corals, one species of 

 Delthyris and two or three species of Turritella (Murchisonia), &c., occur in abundance. 



3. Immediately below the preceding (though in a reversed section, and therefore on the dip side) are 



