462 PKOCEEDINGS OP THE GEOLOGICAL SOCIETY. [May 24, 



rine denudation may have taken place, says * that the "Weald was 

 denuded " probably to a great extent also by the influence of atmo- 

 spheric agencies." In 1864 he further explained f his views, and 

 gave many arguments against the marine theory. 



1. Theory of Fracture. — Mr. Hopkins, and other writers on this 

 subject, dwell much upon the longitudinal dislocations of the Weald, 

 and draw the inference that the weU-known longitudinal valleys 

 are the direct results of these dislocations. But, if this be so, the 

 valleys and the faults ought to coincide, not only in direction, but 

 absolutely. This they rarely or never do. 



The longitudinal valleys run along the outcrop of the softer beds, 

 or those most easily eroded. This of itself is some evidence of 

 their formation by erosion. But the strike of the beds of any 

 area necessarily corresponds in direction with its hues of disturb- 

 ance, being alike due to elevatory forces acting from beneath. 

 Hence we see that the strike and the faults are effects of the same 

 cause ; while the longitudinal valleys are determined by the strike 

 alone, and may be seen to be so in districts where faults are 

 altogether absent. 



Against Mr. Hopkins's mathemathical deductions we neither 

 presume nor wish to contend. It is quite certain that longitu- 

 dinal disturbances have taken place, and it is certainly possible 

 that transverse fissures may have been formed which gave the ori- 

 ginal direction to the rivers which now run through deeply eroded 

 valleys. Such dislocations, however, must have been mere fissures, 

 and nothing more. There was no possibility of the beds slipping 

 away on either side, nor has any vertical displacement taken place. 

 Therefore the transverse valleys are still " valleys of denudation." 

 Moreover, it is somewhat surprising that the Geological Survey 

 has been unable to find any very imjDortant dislocations in any 

 other parts of the Chalk escarpment. The Gault and Greensand 

 lines have been drawn with care, but no marked disturbances are 

 known ; nor, as Mr. Hopkins admits, is there any proof that dis- 

 locations of any kind occur even in the transverse valleys them- 

 selves. 



2. Marine Theory. — The view held by many geologists upon the 

 denudation of the Weald is that, during a long course of time, the 

 waves of the sea have formed the long lines of escarpment passing 

 round the Weald, which are likened to sea-chfis, such as are now 

 being formed by the action of the sea on the Chalk of Kent and 

 Sussex. 



We think the commonly received marine theory untenable for 

 the following reasons : — 



(1.) The foot of the Chalk escarpment J, and also that of the 

 Lower Greensand, are not at the same level aU round the Weald, as 

 every sea-cliif must necessarily be. This inequaUty of level can 

 hardly be explained by unequal elevations during the last rise of 



* 'Physical Geology and G-eography of Great Britain,' 1st edit. 1863, p. 64. 



t Op. cit. 2nd edit. 1864, p. 75. 



X See Eamsay, op. cit. 2nd edit. p. 77. 



