and FresJilsoater Deposits of Easteiii Norfolk. 379 



We may imagine in like manner masses of chalk and over- 

 lying drift to have fallen from cliffs, and to have been forced 

 sideways over a floor of horizontal chalk ; but it appears to 

 me impossible, even if we adopt this hypothesis, to explain 

 how the Old Hythe pinnacle of chalk (see p. 367) became en- 

 veloped by drift, and this drift in great part vertical and rest- 

 ing on horizontal crag and chalk. It seems necessary first to 

 suppose that a needle of chalk was thrown down on horizon- 

 tal drift, and then that the whole was forced by lateral pressure 

 into a vertical position, the fundamental rocks remaining un- 

 moved. 



It cannot be objected to explanations of this kind that an- 

 cient clifJ'sand adjoining needles of chalk are no longer visible, 

 because they may have existed when the country was sub- 

 siding, and they may have been removed by denudation, when 

 brought down within the action of the waves. 



Bi/ pressure of drift ice. — Tiiere is still another cause, 

 hitherto, I believe, overlooked, by which great foldings and 

 contortions may be produced in the upper portions of banks 

 of sand and gravel, while the lower remain undisturbed; I 

 mean the stranding of icebergs and large masses of packed 

 ice. In different parts of Scotland, Sweden, Norway, and 

 probably everywhere in Europe where drift is found contain- 

 ing erratic blocks, between the latitudes 50° and 70° north, 

 coiled and folded beds of loam, gravel, and sand are fre- 

 quent, and I have often seen them in Scotland resting on and 

 covered by strata which remain horizontal. 



In the account given by Messrs, Dease and Simpson of 

 their recent arctic discoveries, we learn that in lat. about 71° 

 N. long. 156° W. they found " a long low spit named Point 

 Barrow, composed of gravel and coarse sand, in some parts 

 more than a quarter of a mile broad, which the pressure of 

 the ice had forced up into numerous mounds, that viewed 

 from a distance assumed the appearance of huge boulder 

 rocks*." So many facts indeed have come to my knowledge 

 of the manner in which masses of ice, even of moderate size, 

 in the Baltic, and still more in the Gulf of St. Lawrence, 

 push before them large heaps of boulders, that I can scarcely 

 doubt that lateral pressure, exerted under favourable circum- 

 stances by drift ice on banks of stratified and incoherent sand, 

 gravel, and mud, is an adequate cause for producing consider- 

 able flexure and dislocation. The banks on which icebergs 

 run aground occasionally between Baffin's Bay and New- 

 foundland are many hundred feet under water, and the force 



* Journ. of Roy. Geograpli. Soc, vol. viii. p. 221. 

 2 C 2 



