CHAPTER XXXII. 

 VALLEY OF ELEVATION OF WOOLHOPE. 



Introduction. — Form of the Valley. — Description of the Silurian Rocks which 

 constitute its encircling ridges. — Ancient dislocations which determined its 

 form, fractures, and drainage. — Modern dislocations and landslips. — Drifted 

 matter. (See General Map, enlarged Map opposite page, coloured sec- 

 tions, PL 36. figs. 9a and 9b. and wood-cut p. 428.) 



THE phenomena of valleys of elevation in rocks of sedimentary origin were first brought 

 into prominent notice in England by Dr. Buckland, in an able sketch of the district of 

 High Clere and Kings Clere 1 . Since that period the attention of geologists has been 

 directed to certain crateriform cavities, which, composed of trap or volcanic rocks, have 

 been termed by Von Buch "craters of elevation," and their external folds having an 

 eccentric dip are supposed to have been forcibly raised from the centre into their present 

 positions. This opinion, ably supported by some leading geologists, including MM. Elie 

 de Beaumont and Dufrenoy, has met with equally powerful opponents in Mr. Lyell, 

 M. Constant Prevost and others. The followers of Von Buch contend, that the relative 

 position of these masses and their transverse rents, demonstrate upon mechanical prin- 

 ciples, that violent and sudden expansion from centres of eruption could alone have pro- 

 duced such results, — their opponents asserting, that in lithological structure and method 

 of arrangement, the strata composing many of these so called " elevation craters" are 

 nothing more than the natural products, whether submarine or subaerial, which being 

 vomited from craters, have fallen upon or flowed down their sides. It is not my in- 

 tention to enter into this warmly agitated question ; but, notwithstanding the eminence 

 of the rival disputants, I cannot avoid expressing an opinion, that in this, as in many 

 other points of geological theory, discrepancies of opinion may often be reconciled, if 

 the contending parties would examine for themselves the same natural phenomena. 

 Mr. De la Beche, in his able work, " Researches in Theoretical Geology," p. 112, has 

 well observed, that " amphitheatres or valleys of elevation merely require the ejection 

 of volcanic matter through their centres to become the much disputed craters of eleva- 

 tion." Nature, therefore, it appears to me, may be so appealed to by contending 



1 Geological Transactions, vol. ii. p. 119. 



