The Chalk Bluffs at Trimingham. 401 



the flint bands in which, were nearly horizontal. On the top of each 

 was a layer of coarse gravel, followed by much stratified sand with 

 occasional bands of clay. The eastern of these boulders projected 

 slightly in advance of the western one, and their ends, so far as the 

 slipped material allowed us to determine, were about nine yards 

 apart.^ The clay just mentioned is not pebbly, but below high- 

 water mark and perhaps eight feet vertically beneath the base of 

 the cliff typical boulder-clay was exposed on the beach. About 

 fifty yards to the east chalk showed up beneath this, and on it, as 

 we walked in that direction, we saw for a considerable distance 

 patches of boulder-clay. Evidently ancient denudation has removed 

 the Forest Bed and Leda myalis sand from this part of the coast, so 

 that for a considerable distance the bluish-grey boulder-clay rests on 

 a very slightly irregular surface of chalk. 



We may now mention one or two fundamental weaknesses which, 

 to our minds, were inherent in Mr. Eeid's hypothesis from the first, 

 but had apparently escaped his notice. He offers his readers only one 

 alternative to the action of an ice-sheet as an explanation of these 

 chalk-masses either at Trimingham or where they are admittedly 

 boulders, viz. transport by icebergs, and dismisses the latter on the 

 ground that the sea, supposing it to have existed, would have been 

 too shallow to be navigated by bergs of sufficient thickness to float 

 such huge masses of rock. We do not dispute this objection, but 

 are surprised to find that he has not discussed or even noticed 

 Colonel Feilden's observations on the transporting power of an 

 icefoot — i.e. of ' rafts ' of ice — which were made in Smith Sound 

 during Sir G. Nares' Arctic expedition.^ Such rafts, as the chalk- 

 masses need not have travelled far, would be much more probable 

 vehicles than bergs. 



Again, the reader must remember that the section in the Survey 

 Memoir (p. 116) exhibiting the Trimingham mass as a second stage 

 in boulder-making is only hypothetical, as its author virtually 

 admits in the following sentences (p. 115) : — " If the ice-sheet, 

 instead of flowing over the beds, happens to plough into or abut 

 against them, it would bend up a boss of chalk, as at Beeston. 

 A more extensive disturbance, like that at Trimingham, drives 

 before it a long ridge of the beds, and nips up the chalk, till, like 

 a cloth creased by the sliding of a heavy book, it is folded into an 

 inverted anticlinal. A slight increase of pressure and the third 

 stage is reached — the top of the anticlinal being entirely sheared off, 

 the chalk boulder driven up an incline and forced into the overlying 

 boulder-clays." An explanation no less clear than confident, but 

 can any instance be cited which affords even an approach to a valid 

 proof that either a large glacier or an ice-sheet can exercise this 

 ' rooting ' power on a fairly solid rock. Statements such as that 

 just quoted are no doubt common ; ice has been credited with the 

 excavation of valleys, fjords, and important lake basins, but when 



1 A third and smaller chalk-mass was exposed in the cliff about twenty yards still 

 further east. 



2 Quart. Journ. Geol. Soc, vol. xsxiv (1878), pp. 563-566. 



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