28 Transactions of the 



Geology and Mineralogy. — We have already said sonietliing of 

 the general physical features of the MendijD Hills, on the southern 

 slope of which Cheddar is situated, and it remains that we should 

 state their geological characters. The central axis of the range is 

 one of old red sandstone, flanked by thick beds of mountain lime- 

 stone. These latter rocks are inclined to the horizon at very various 

 angles, sometimes of 30" and again as much as 70"". In most 

 places they completely overlie the older sandstone, but in others 

 it crops up to the surface through denudation. The amount of 

 this denudation, we may say, along the whole course of the Men- 

 dips has been enormous. Professor Ramsay has even asserted 

 that the missing beds, removed from the summit of the Mendips, 

 must have been almost a mile in thickness ! The extent of the 

 conglomerate deposit which skirts these hills for so great a por- 

 tion of their course, and fills up so many of the hollows in their 

 rolling undulations, bears evidence to such an hypothesis, and 

 Professor Ramsay fully supports it by his observations on the 

 relation of the carboniferous limestone to the other rocks of this 

 district. 



The general character of the carboniferous limestone of the 

 Mendip Hills is said by Professor Ramsay to be much the same 

 as at Bristol ; the lower shales present similar characters, the 

 lower limestones are replete with encrinites, ofte:i shown, when 

 weathered, to constitute the greater part of numerous beds, and 

 the upper beds are often oolitic, corals being far more abundant 

 in the latter than in the lower beds. There is more chert observ- 

 able in the lower part of the Mendip beds, and sometimes this 

 substance is abundant in them.* 



As has been mentioned above, there is a very extensive deposit 

 of what has been termed ' dolomitic conglomerate* flanking the 

 carboniferous limestone of the Mendips. It rests unconformably 

 on the subjacent strata, and is doubtless of Triassic age. At 

 Cheddar this formation is abundantly seen, and at Draycot, in the 

 neighbourhood, it is largely quarried under the n;ime of 'pudding- 

 stone.' We have seen polished specimens* of the rock from these 

 quarries, and it certainly forms a vei-y beautiful marble, variegated 

 with colours, owing to the many pebbles which it contains. It is 

 their presence which gives it its curious name. 



The flat expanse of the Axe level, lying at the base of the 

 Cheddar Cliffs, is unquestionably an ancient estuary. Indeed, at 

 no very remote period a branch of the Severn perhaps extended 

 as far as Glastonbury Hill, and this great tract was only gradually 

 converted into dry land by the deposition of mud from the waters. 



* Eamsay, ' Formation of Rocks in South Wales and South- Western England,' 

 Mem. Geol. Survey, vol. i. p. 127. 



