186 Correspondence. 



East Yorkshire, which appeared in the GtEOlogical Magazink for 

 October, 1866. A comparison was there made between escarpments 

 and modern sea clififs, and I remarked "on the Yorkshire coast, we 

 pass in the same line of cliffs, from Lias in the north, through all the 

 Oolitic series in succession, to Chalk in the south. Such is never 

 the case with an inland escarpment. This presents the same set of 

 beds throughout the entire length." This I believe to be true of all 

 the Secondary escarpments of England, as it is known to be true 

 of all sea-cliffs whatever. But Mr. Mackintosh observes, " this 

 theory is not applicable to many parts of the south-west of England 

 and other districts, where the sea, in making cliffs, shows a tendency 

 to follow the strike, and where many inland cliffs run obliquely to 

 the strike. Numerous instances might be brought forward, did space 

 permit." Now it is not enough to show that any line of cliffs has 

 " a tendency to follow the strike," though this would be an interest- 

 ing fact. Cliffs might even for a short distance coincide with the 

 strike, as in some part of their course they probably would do ; but 

 can Mr. Mackintosh give a single instance of a long line of modem 

 sea-cliffs following the strike, and being at all comparable to what 

 we all know as escarpments ? Does not a simple inspection of any 

 geological map, show that different formations are intersected by the 

 sea along the same line of cliffs ; and that " the sea, where we now 

 see it at work, pays no regard to dip and strike ? " 



Mr. Mackintosh's second objection, that, in the south-west of 

 England, " many inland cliffs run obliquely to the strike," is more 

 difficult to meet. We all understand what is meant by the term " a 

 sea-cliff," but we are by no means agreed upon the definition of "an 

 escarpment." The subaerialists, I presume, limit the term to such 

 lines of hills as, more or less constantly, run along the strike, and 

 whose steepest sides, the " scarp," faces the dip : in this sense I 

 believe the term is generally used by geologists. The Chalk, 

 Greensand, and various Oolitic " escarpments " of east and central 

 England are of this character. If, therefore, any hills were proved 

 to run obliquely to the strike, such would probably not be called 

 escarpments. It is quite possible that of such hills some may be 

 true inland sea-cliffs, in which case marine deposits will probably 

 be found at their bases. It would be interesting to have examples 

 of some of the numerous instances to which Mr. Mackintosh refers. 



At present I think the point at issue may be simply stated thus — 

 Can the advocates of the marine theory produce any undoubted traces 

 of marine action, along the many hundred miles of inland cliffs 

 we all call " escarpments," or any undoubted marine deposits, not 

 Glacial drift, at their bases ? Or, on the other hand, can they pro- 

 duce a single instance where the sea is now forming a long con- 

 tinuous line of cliffs having any analogy to such escarpments ? 



W. TOPLKY. 



Geological Survey Office, Jermyn St., 

 March 9(h, 1867. 



