g4 Rev. A. Sedgwick on the Geological Relations and 



band of clay surmounted by striped slaty ferruginous beds, which gradually pass into a coarse 

 yellow magnesian limestone. 



This red dolomitic sandstone rises and falls in long sweeping undulations, and may be traced 

 to a quarry on the side of the Chesterfield road, where it preserves nearly the same colours and 

 external characters, and is worked for the same purposes. 



In the whole rant^e of the magnesian limestone I know of no deposit which can be compared 

 with that which is here described ; and it is the more remarkable, as it is found in the heart of 

 the formation, and nearly in a line with the finest specimens of crystalline dolomite*. 



3. On Bolsover Moor, about two miles east of the village, is a beautiful yellow crystalline 

 limestone, which is extensively quarried for building. Its lustre is pearly, and excepting the 

 colouring matter and the minute black spots which are scattered through it, it contains very 

 little impurity. Some of the beds become so granular as to pass into the preceding modification. 



(No. I. p. 82.) 



4. Amono- the rocks forming the beautiful ravine called Cusswell Crags, are some fine dolo- 

 mites • but they are irregularly bedded, are associated with compact, cellular, and earthy 

 varieties and have not been quarried. There arc, however, some beds on the hill to the north- 

 west of the ravine which have been used for building, and, except in colour, resemble those of 

 Bolsover Moor. In passing into a solid state, some of these beds have penetrated each other ; 

 so that their separation is not represented by a plane superficies, but by a number of imperfectly 

 crystalline points and protuberances, which give to the surfaces of the blocks an appearance re- 

 semblin<T artificial rustic work. These natural surfaces have been occasionally used in ornamental 

 architecture. 



5. The neighbouring quarries of Steetley are of considerable extent, and of great antiquity. 

 The rock laid bare is not more than twenty feet thick. It is divided by a number of irregular 

 horizontal partings into beds from one foot to three feet thick ; and it is also intersected by a 

 number of irregular transverse seams and fissures. The finest specimens are of a greyish white 

 colour, crystalline, fine-grained, and of a beautiful shining pearly lustre. The top of the quarry 

 is composed of thin soft yellowish beds much stained with the black spots before alluded to f. 



6. In the neighbourhood of Roach Abbey are also some very ancient quarries of dolomite of a 

 beautifully greyish white colour. In its mode of bedding, thickness, mineralogical character, and 

 geological position, it is nearly identical with the Steetley rocks above described; but it is more 

 finely grained. Only four or five beds are worked. The strata above them and below them are 



* The beds above described are an instance of the extensive operation of mechanical agents 

 during the deposition of the magnesian limestone. Some of the coarsest specimens probably con- 

 tain as much as 30 per cent of siliceous sand. The Rev. J. Holme examined one of the finest 

 cistern beds, and from 100 grains obtained the following results : 



Lime 28.750 



Magnesia 11.125 



Carbonic acid 34.750 



Silica 20.250 



Red oxyd of iron and alumina 3.375 



Earthy muriates of soda, lime, and magnesia ? 0.250 



Water and loss 1.500 



100.000 



t Many ancient churches, and some monastic buildings, of which the ruins exist in the neigh- 

 bourhood, were formed of materials derived from these quarries. This stone was also used in the 

 construction of Clumber House, Worksop Manor, and some other noble modern edifices. 



