Correspondence — Mr. A. H, Green. 



41 



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: W 



The mean height of the base is about 700 feet above the sea, and 

 it will give the minimum of oscillation if we suppose the land 

 lowered to this amount. But even on this supposition we shall 

 require the lowest point to be raised 375 j^ 



feet, a point only two chains off 300 

 feet, a point seven chains further on 200 

 feet, and so on ; while at the other end 

 of the line additional depression will be 

 necessary, and the heights of the first 

 three points shew that this depression 

 will not always increase uniformly in 

 the same direction. I may add that I 

 have neglected the gashes cut by small 

 streams in the flank of the slope, and 

 taken only the general line of the cliff : 

 had all the lesser windings been followed 

 the result would have been still more 

 striking. This way of treating the mat- 

 ter is, I think, fairer to my opponents, 

 because, according to their view, these 

 gullies were formed after the termina- 

 tion of the process which gave rise to 

 the escarpment itself. 



In order to shew more clearly to the 

 eye the facts I am insisting on I have 

 thrown the details of another case into 

 the form of a diagram given in the 

 woodcut annexed. The dotted horizontal 

 line there represents the average level of 

 the base of the escarpment, and the dis- 

 tance between this dotted line and the 

 hard black line at any point shews the 

 difference in level between the actual 

 base at that point and its mean height, 

 and therefore the amount of additional 

 elevation or depression required to turn 

 the escarpment into a sea-cliff. The hori- 

 zontal and vertical scales are each two 

 inches to a mile. 



The cases just given have been taken 

 at random, and, I believe, represent very 

 fairly the general state of the escarp- 

 ments of the Carboniferous rocks in Lan- 

 cashire, Yorkshire, Staffordshire, and 

 Derbyshire ; to turn these into sea-cliffs, 

 sea- saw work like that described would 

 be required for every one, alike in char- 

 acter but varying in amount for each ; 

 now, independently of the improbability 





