the London and Hampshire Basins. 37 



tlie boulders at Selsey must have occupied the Weald, and left 



N.E. 



traces of its presence, as it has done in the valley of the Thames 

 and on the coast of Sussex, if the Weald had been in existence. 

 The case is still stronger taking the levels of the Highgate Hills, 

 or the site of Stoneheuge and Salisbury Plain ; unless, indeed, 

 it be insisted on, that the coast-line has sunk whilst the inner 

 country has risen, or vice versa ; or that the boulders which once 

 covered the Weald have melted away by atmosphei'ic erosion, — 

 both propositions too bold even for the most plastic schemes of 

 modern geology. With the help, then, of the boulder drift we 

 are brought to the conclusion that the upburst of the Wealden 

 and the rise of the whole anticlinal were posterior to the sera of 

 the northern drift, and the transport by icebergs in this part of 

 the world. 



Under what circumstances we parted with the climate of the 

 glacial period we need not now inquire. The tertiary deposits 

 were still persistent on the chalk, and the boulder drift over all. 

 Whether we had here an archipelago or an open ocean, a disloca- 

 tion takes place, whether subaerial or subaqueous, or partly both, 

 is immaterial ; the anticlinal line about which so much has been 

 said suddenly rises, the two great synclinals on either side are 

 brought into existence, and we have the commencement of the — 



Diluvial Epoch. 



My exposition of the evidence in favour of the violent excava- 

 tion of the Weald by the joint operation of earthquake and dilu- 

 vial currents is already in print, and it is unnecessary to repro- 

 duce the proofs in this place : I shall briefly make allusion to 

 some of the points. 



Mr. Hopkins has given us to understand, that the first up- 

 burst of the Wealden strata at least had a character of totality. 

 And he adduces proofs from mathematical and mechanical prin- 

 ciples, of a unity and synchronism in the fissures, both longitu- 

 dinal and transverse, which he has traced out there. In the 

 map which accompanies Mr. Hopkins's memoir on this subject 

 (Trans, of Geol. Soc. vol. vii.), he has erroneously drawn an 

 imaginary line of demarcation round what he calls the " disturbed 

 district," although I had already shown that the same phajnomcna 

 of dislocation and disturbance had been continued on westward 

 of that line, or in other words, west of the Alton Hills. Mr. 



