Ch. xiii.; 



CRAG. 181 



as one of the ' Needles ', or insulated rocks of chalk, which 

 projected 120 feet above high water-mark, at the western 

 extremity of the Isle of Wight, fell into the sea in 1772 *, 

 so a pinnacle of chalk may have been precipitated into the 

 tertiary sea, at a point where some strata of the crag had 

 previously accumulated. The beds of flint and chalk in the 

 above diagram appear nearly horizontal, but they are in fact 

 highly inclined inwards towards the cliff. The rapid waste of 

 the Norfolk coast might soon enable us to understand the true 

 position of this mass, if observations and drawings are made 

 from time to time of the appearances which present themselves. 



Perhaps it may be necessary to suppose, that subterranean 

 movements were in progress during the deposition of the crag, 

 and the extraordinary dislocations of the beds, in some places, 

 which in others are perfectly regular and horizontal, may be 

 most easily accounted for by introducing an alternate rise and 

 depression of the bed of the sea, such as we know to be usually 

 attendant on a series of subterranean convulsions. Several of 

 the contortions may also have been produced by lateral move- 

 ments. 



Passage of marine crag into alluvium. By supposing the 

 adjoining lands to have participated in this movement, we may 

 explain the origin of those masses of an alluvial character 

 which contain the detritus of many rocks, the bones of land 

 animals and of drift timber, which were evidently swept down 

 into the sea. The land-floods which accompany earthquakes 

 are, as we have seen, capable of transporting such materials to 

 great distances f , and, as part of these alluviums must be left 

 somewhere upon the land, we may expect to find, on exploring 

 the interior, a gradual passage from the terrestrial alluvium 

 to that which was carried down into the sea, and which alter- 

 nates with marine beds. 



The fossil quadrupeds imbedded in the crag appear to be 

 the same as those of a great part of the alluviums of the interior 



* Dodsley's Annual Register, vol. xv. p. 140. f Vol. i. chap. 25. 



