68 Rev. A. Sedgwick on the Geological Relations and 



the formation above described. In some of the beds, especially in the harder 

 varieties of sandstone, it is disseminated in the form of yellow and red ochreous 

 concretions, which rarely pass into a true haematite ; and it often gives a deep 

 red tinge to the argillaceous bands which are interposed between the strata. 

 In the escarpment under the yellow limestone at Micklebring, a few miles 

 south of Doncaster, it is deposited in the form of an earthy red oxyd in beds 

 of considerable thickness, which alternate with a red-coloured micaceous 

 sandstone. 



Such are the leading characters of the inferior red sandstone ; and an 

 attempt at a further subdivision of it in a more general description, which has 

 no immediate reference to individual sections, would not, 1 think, be attended 

 with any advantage. In the arrangement of the subordinate parts there does 

 not appear to be any constancy, if we except the red and variegated marls 

 which are so commonly found immediately under the limestone, and also the 

 obscure conglomerates above mentioned, which, in a few instances, occur in 

 the same position. 



Range and extent of the Loicer Red Sandstone, ^c. ^c. 



From the edge of Derbyshire to the river Air, this deposit is generally confined to the middle 

 or lower part of the terrace, which is crowned by the magnesian limestone. Its superficial extent 

 may therefore be represented on a geological map by a shade of colour traced on the western 

 border of the limestone. This is the mode adopted by Mr. Smith, whose delineation of the range 

 through the southern parts of Yorkshire is extremely accurate. 



In tracing the formations from the south towards the north, the inferior red sandstone is, I 

 believe, first seen in a characteristic form near Barlborough, not far from which place a quicksand 

 is found immediately under the escarpment of the yellow limestone. Following the demarcation 

 into the county of York, we find the deposit well exhibited at Hart Hill in the form of a coarse 

 red micaceous sandstone, the upper part of which becomes more thinly bedded and of finer texture, 

 and is surmounted by marl beds and the inferior strata of the yellow limestone. In the two next 

 valleys of denudation, and on the hills above North Anston and South Anston, the coal-measures 

 and limestone are separated from each other by a coarse variegated sandstone, in some places of a 

 dark brick-red colour, which has innumerable false planes of division, and is surmounted by slaty 

 red sandstone and red marl. At Maltby and Micklebring the deposit has the same general cha- 

 racters ; but a little further to the north, between Clifton and Conisburgh, the beds are more 

 coarse and indurated, and have been extensively quarried. 



In all this part of the range, though the mineralogical characters are nearly constant, the 

 thickness of the deposit is extremely variable : for in some localities it forms a mere band, ranging 

 through the mid region of the escarpment immediately under the magnesian limestone ; while in 

 others it occupies all the lower part of the terrace, and probably extends considerably to the west 

 of its base. 



At the village of Cadeby (on the north bank of the river Don) it becomes of complex structure, 

 and of great thickness. The lowest parts of the formation are not exposed, being buried under 



