JURASSIC. 101 



This disposition of the group suggests that it may have occupied an 

 Lacustrine and estua- isolated estuai'ine 01" lacustrine situation ; the thin- 

 ^^°®' bedded and ripple-marked characters point to the 



existence of shallow-water currents, while the mass of clays and shales 

 would indicate a change to still and deeper water ; but the source of the 

 ferruginous colouring, matter which separates it so decidedly from the 

 associated groups is quite unknown. 



Jurassic. 

 No. 9. — In upward continuation of the section in which the Ceratite- 



bearing portion of the trias occurs at the western 

 Situation. 



side of the district, is a very varied and mingled 



group of arenaceous, argillaceous, and calcareous rocks, liable to consider- 

 able change laterally, in thickness and composition, but preserving a 

 well-marked individuality of aspect, by which it can generally be 

 recognised without difBculty. 



In the lower part of this series strong bands of thick-bedded, 



soft, ferruginous sandstone, of red, variegated, or 

 Lower part. . • i t 



yellow colour, alternate in places with liver- 

 coloured and grey ripple-marked bands. To these succeed thick, argil- 

 laceous, yellow limestone, soft rusty-looking sandstones, grey gypseous 

 and pyritous clays and soft, powdiery, white sandstones, apparently 

 largely composed of white quartz and felspar grains in a white earthy 

 or chalk-like matrix. 



Among these beds and in the body of the group, bands of haematite 



several feet in thickness occur, and thinner layers 



HsBmatite. . , . , • i i 



of " golden oolite, each grain having a burnished 



ferruginous coating (this latter rock exactly resembling in character 



the golden oolite of Kach and resulting from the decomposition of 



an oolitic limestone). Above all these are coarse brown sandstones 



and yellow marls or mudstones, white cavernous sandstones, and 



bands of grey hard limestone of inferior thickness and less constant 



occurrence than those below. 



( 101 ) 



