Geology of the South-east of Devonshire. 487 



of the Exe must also in places be very great. This system of faults, producing an 

 upcast to the east, is proved to be referable to the tertiary period, by the beds which 

 it traverses ; and the movement was probably attended or produced by those causes 

 which converted into dry land what before was covered by water, and imparted an 

 uniform elevation to a great portion of the south of England, without reference to 

 geological age. 



The condition of things which had so long favoured the production of calcareous 

 beds, and had allowed time for the segregation of the layers of flint, as well as the 

 slow conversion of the calcareous shells and corals into siliceous casts, was suc- 

 ceeded by the partial destruction and removal of the chalk, whilst the uninjured 

 state of the flints, which remain in place, shows that the process could not have 

 been a violent one. That period of destruction immediately preceded the true 

 commencement of the tertiary epoch, during which siliceous sands of considerable 

 thickness were accumulated, and those internal changes took place whereby the 

 sihceous breccias and grey-wethers were produced. To this again succeeded an- 

 other extensive period of destruction and removal ; the whole constituting a suc- 

 cession of events which indicate very variable conditions over the same place, and 

 imply a long lapse of time. 



The interval between the completion of the older series of rocks and the com- 

 mencement of the new red sandstone period must have been very great. The 

 early deposits, originally consisting of mud, ooze, or sand, had been placed in con- 

 ditions by which great internal changes of structure and arrangement were super- 

 induced ; for in the materials which compose the lower new red conglomerate beds, 

 we have abundant evidence that when the abrasion commenced from which the con- 

 glomerates resulted, the older deposits had passed into the same condition of com- 

 pact siliceous rocks, fissile slates, and crystalline limestone which they now present. 



We can never hope to know enough of the rate of increase of deposits at present 

 in progress to serve as a guide in the important question of the lapse of time during 

 geological periods ; but as accumulations can only proceed pari passu with destruc- 

 tion and removal, it is perhaps in the action of breakers and the waste along our 

 coasts that we have the most available means of approximating to the vast series 

 of years during which our several formations were in progress ; but of the inter- 

 vals which elapsed from one to the other we can form no conjecture. 



In certain instances destruction has been local, and evidently exerted over the 

 same spot for a long continuance ; thus the limestones of Babbacombe still preserve 

 their massive tabular character ; but close by, as at Petit Tor, the calcareous strata 

 have been reduced to a few feet in thickness, of which the breccia is all that remains. 



A very remarkable line of elevated strata, with a direction west 30° north to east 

 30° south, crosses the west of Devon, from Hope's Nose on the east of Torbay to 



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