Correspondence. 569 



examples ; but lias it not occurred to the author, that towards the 

 close of the Drift period, most of the principal escarpments of the 

 centre and north of England which run along the strike, must have 

 been sea cliffs when the land was from 200 to 400 feet lower than 

 it is. 



(4) " If escarpments have been formed by the sea, there ought to 

 be at their foot some resultant, a beach or other marine deposit ; but 

 this is not the case (except where masses of Boulder Drift end near 

 the bottom of a ridge)," etc. To this I reply that these " masses of 

 Boulder Drift" are very often level terraces of marine origin, and to 

 all intents and purposes sea-beaches, or beds ; but besides this, there 

 are true sea-beaches at the foot of escarpments, as for example, in 

 the Vale of Gloucester, at the foot of the Cotswold Hills. 



I would also remark, that it is surprising to me, how any one who 

 believes in the formation of Professor Eamsay's " Planes of Marine 

 Denudation," can question the power of the sea to produce escarp- 

 ments, as some escarpments are only the lines along which the sea 

 left off its work in the formation of such planes. 



In conclusion, I will only express a very strong conviction that 

 we shall never arrive at true views of the operation of nature in 

 sculpturing the surface of the earth, unless we take into considera- 

 the effects of all possible agencies, and give them their due place in 

 the great work. I remain, yours truly, Edwakd Hull. 



3, Hamilton Park. Terrace, 



Glasgow, 18 Nov., 1867. 



ON CLIFFS AND ESCARPMENTS. 

 To the Editor of the Geological Magazine. 

 Sib, — I know very little about escarpments in the soft newer 

 formations, but as I have seen a fine cliff cut by the Atlantic in the 

 hard, older rocks that occur in the west of Ireland, and also in the 

 Boulder-drift, perhaps I may be allowed to make a few remarks on 

 Mr. Whitaker's notes on cliffs in his " Comparative table of the 

 distinctive features of Escarpments and Cliffs," ' 



" Cliffs." Remarks. 



(a) " Rarely run along the strike,^ (a) It rarely happens that a sea-cliff 



but at all angles to it, and cut through can keep to the out-crop of a bed, for it 

 many formations in succession." is highly probable that the beds were not 



raised to their present position horizon- 

 tally. However, it does occur sometimes, 

 although the beds may not be per- 

 fectly horizontal ; as, for instance, on the 

 westerly coast of Aranmore, Galway Bay, 

 where a bed of shale for miles forms the 

 base of a perpendicular cliff : also on the 

 coast of Clare, where a thin bed of lime- 

 stone in the Coal-measure shales acts in 

 a similar way. At the base of a drift- 

 cliff, there is often a bed of stiff clay; 

 just as it will ofren occur at the base of 

 a drift-cliff formed by a stream. 



1 Geol Mag. November, 1867. Vol. IV. p. 491. 

 ' Ought not this to be out-crop, or basement ? 



