GEOLOGY 



swell out suddenly and to change its nature. It takes on the form of a 

 white calcareous sandstone, 60 feet in thickness. The lower parts are 

 more siliceous and the higher more calcareous, and the whole is massive 

 and irregularly bedded. A mile to the north-east of the town, in the 

 Rock valley, a similar rock of equal thickness, but of a red colour, 

 is quarried. The following analyses of the two varieties have been 

 published r 1 



MANSFIELD WHITE SANDSTONE MANSFIELD RED SANDSTONE 



Silica 5!'4O Silica 49'4 



Carbonate of lime 26*50 Carbonate of lime 26-5 



Carbonate of magnesia . . . . ij'<)8 Carbonate of magnesia .... i6'i 



Iron, alumina, etc 1*32 Iron, alumina, etc 3-2 



Water and loss 2'8o Water and loss 4-8 



lOO'OO lOO'OO 



This sandstone may be traced by quarries running in a N.N.E. 

 direction across the country to Pleasley Vale, between Pleasley Forge and 

 Pleasley Works, and so out of the county. As the dip of the strata 

 generally is eastwards, it is probable that the bulk of the limestone lying 

 to the east of the outcrop of the sandstone is higher in the series than 

 that to the west. Thus the Magnesian Limestone as a whole may be 

 divisible into two parts, the sandstone forming the base of the higher. 

 The upper Magnesian Limestone is seen to overlie the sandstone at the 

 quarries, and at a higher level it expands to a rock of beautiful character 

 at Mansfield Woodhouse. In the quarries there worked it is a glistening, 

 finely crystalline limestone of yellowish white colour, with scattered black 

 specks, and having the composition : 



Carbonate of lime 5 I- 65 



Carbonate of magnesia 42'6o 



Silica 3'7 



Water and loss 2*05 



lOO'OO 



From this quarry in a direction parallel to the strike of the sandstone of 

 Mansfield the Bolsover Moor Quarry is reached, both quarries yielding 

 similar stone of celebrated building properties. 2 This same type of lime- 

 stone occupies the surface for the rest of the range in the county, and 

 near Warsop becomes very finely laminated and perforated with numer- 

 ous fine holes, whence some extra-soluble crystalline ingredient has been 

 dissolved out. At Streetly near Worksop the limestone is also ' white 

 and crystalline.' 



It will be noted in a geological map that to the south of Mansfield 

 the surface occupied by the Magnesian Limestone is about 1 1 2 miles 

 broad, but to the north of that town it is 6 miles broad. This is partly 

 due to the thickening of the lower beds, but also to the coming on of a 



1 Geol. Survey Mem. sheet 82, S.E. 



* See ' Parliamentary Report on Building Stones, 1839.' 



I J 7 3 



