65 



(1) Dolomite, a simple crystalline rock. — (a) Arenaceous dolomite, 

 coarse, nearly incoherent, often in minute rhombs. — (b) Small- 

 grained dolomite. Many quarries of this variety are described as ex- 

 isting on the back of the deposit, and extending from the neighbour- 

 hood of Mansfield to Bramham Moor. The crystalline beds pass into 

 others of mechanical structure, and in some extreme cases contain 

 20 or 30 per cent of siliceous sand, — (2) Compact magnesian lime- 

 stone. — (3) Laminated. — (4) Earthy.- — (5) Masses of irregular con- 

 cretionary structure. — (6) Beds or concretionary masses of crystalline 

 limestone without magnesia. Examples of these are derived from 

 quarries near Ripon, Knaresborough, and Newton Kyme, &c. — (7) 

 Brecciated structure. This modification abounds on the coast of 

 Durham. — (8) Small concretionary structure. — (a) Irregular. — (b) 

 Regular or oolitic. — (9) Large globular concretionary structure. — Of 

 this, four principal modifications are described with minute detail. 

 All these several subdivisions of structure are supposed to have been 

 produced by great internal movements, after the mechanical deposi- 

 tion of the formation. 



§ 4. Lower Red Marl and Gypsum. — This extends from the edge 

 of Nottinghamshire to the banks of the Wharf ; thins off at the two 

 extremities; attains its greatest thickness (perhaps nearly 100 feet) 

 on the right bank of the Ain ; — but has not been discovered in Dur- 

 ham or the northern parts of Yorkshire. 



§ 5. Upper thin-bedded Gray Limestone. —Near Ferry Bridge this 

 contains very little magnesia. In other places it contains subordinate 

 dolomitic beds. It commences at Carlton near Worksop, and ranges 

 without interruption to the left bank of the Wharf. Further north 

 it reappears in several places, under a modified form : and the highest 

 beds on the coast of Durham may perhaps be referred to it ; but 

 the classifications are made obscure by the absence of the lower red 

 marl. 



§ 6. Great Subdivisions of the new red Sandstone which are superior 

 to the dolomitic series. — In Nottinghamshire these consist of two 

 principal deposits. — (a) Upper red sandstone. — (b) Upper red marl 

 and gypsum. — The same subdivisions may be traced near the mouth 

 of the Tees. In the central parts of Yorkshire they are obscured by 

 diluvium. 



By way of conclusion, — the deposits described in § 1 and § 2, are 

 supposed to be the equivalents of the rothe-iodte-liegende, the kupfer- 

 schiefer, and zechstein. — Those described in § § 3, 4, and 5, are in 

 like manner supposed to be the equivalents of the rauchwacke, asche, 

 foliated slinkstein, breccias, and gypsum, which compose the upper 

 part of the Thuringerwald system. The coincidence, in order, mi- 

 neralogical character, and organic remains, seems to be nearly per- 

 fect. In like manner the two divisions described in § 6, are taken 

 as the respective equivalents of the hunter, sandstein and keuper ; 

 and, the enormously thick deposits between the coal measures and 

 the lias, with the exception of the muschel-kalkstein, are thus found 

 to admit of the same natural subdivisions in England and in central 

 Germany. Finally, the author speculates about the origin of the do- 



