416 Geology of the South- East of Dorsetshire. 



forked Down, and in the Isle of Wight, near Newport, and 

 at Yabridge. 



That such must have been the case is further evidenced by 

 the circumstances of the Wealden formations thrust up from 

 under the Purbeck chalk, and by which the chalk elevation 

 has arisen ; for the longitudinal and transverse cracks and 

 fissures have taken place there, as well as in the chalk and 

 plastic clay ; and it would not be difficult to show, that the 

 same longitudinal and transverse cracks occur not only in the 

 Purbeck line at Dartmoor, Quantock, and in the Weald of 

 Sussex, but in the Boulonnais, in Calvados, and Britany ; in 

 all which places the respective deposits of which those countries 

 are formed have been elevated and fissured in the same direc- 

 tions as Purbeck and the Isle of Wight. Thus, the series is 

 from the granite and slate of Dartmoor, through the slate 

 and quartz rock of Calvados, Britany, &c, the transition 

 rocks of the Quantock hills, to the mountain lime and oolites 

 of the Boulonnais, the Wealden rocks of Sussex, the Isle of 

 Wight, and Purbeck, to the chalk ridge traversing the two 

 latter, and the tertiary beds that lie upon the edges of the up- 

 heaved chalk in both. So that, as we here see, in the countries 

 bounding each side of the British Channel, the whole geolo- 

 gical series has been subjected to the same process, and 

 exhibits exactly similar results. Comparing the lines of 

 coast also, the headlands and bays, the discharging rivers, 

 and the valleys that on either side afford trough-like openings 

 into the sea, such as the deep valleys of Charmouth, Sid- 

 mouth, &c, and the chines of the back of the Isle of Wight and 

 of the coast from Poole to Christchurch (lines which equally 

 correspond with the before-mentioned longitudinal and trans- 

 verse cracks and fissures), it would seem that the Channel has 

 resulted from a wide excavation, not deep as affects the sea, 

 but very deep as affects the level of the land ; caused by the 

 action of the sea in the longitudinal line, assisted by the 

 elevatory forces, and producing the transverse lines of coast, 

 as those of Calvados, for instance ; which lines extend across 

 the Channel to similar coast-lines on the English side. 



I have alluded to the valleys of the Char, Sid, &c, described 

 by Dr. Buckland as diluvial (Trans. Geol. Soc., n. s., vol. i. 

 p. 97.), because, although there is no doubt that their excava- 

 tion has been effected by the action of powerful currents of 

 water hollowing out the successive beds downwards, still, as 

 they occur in a north and south direction (the transverse 

 direction of cracks elsewhere), it is almost certain that the 

 original separation of the particles, or, at any rate, the direction 

 of the waters that insinuated themselves between those parti- 



