60 Sir H. H. Howorth— Destruction of the Ghatk. 



the chalky clay itself and its distribution, it is impossible to 

 attribute the disintegration of the chalky and oolitic debris which it 

 contains to any such diurnal causes as are above mentioned. This 

 chalky debris is nearly all angular or subangular, and absolutely 

 different in kind to any marine shingle or river gravel in the world ; 

 and those who have handled, as I have done, many thousands of 

 the lumps of the chalk (it is utterly wrong to call them boulders), 

 with their angular edges and their contour like broken road-metal, 

 cannot, it seems to me, without absolutely forsaking all inductive 

 methods, see in them the debris of marine or fluviatile denudation. 



Not only is the angular form of the pieces of chalk incompatible 

 with a fluviatile origin, but the great masses of shifted chalk and 

 oolite, to which I shall presently refer, are still more so ; while as 

 to the sea, not only do these same arguments apply, but we have 

 no trace in the Fen country, or in the valley of Axholme and 

 its borders, of the continued presence of the sea there consistent 

 with slow marine diurnal denudation — no old sea margins or 

 shingle beds, no rounded pebbles, except Tertiary ones, and no 

 marine debris of the kind we should certainly find, while the 

 whole of the deposits are entirely different to those of an advancing 

 or retreating sea. 



Other people have in these latter years attributed the breaking 

 up of the Chalk to the action of ice, either to land-ice or icebergs 

 or coast-ice. Mr. Jukes-Browne, Mr. Hill, and others have spoken 

 strongly and well on the subject of land-ice, and shown how im- 

 possible it is to credit this stupendous denudation to ice in this form. 

 In addition to what they say, we nowhere find glaciers breaking up 

 their beds in this way, not even in Greenland or Alaska, nor is it 

 credible that they should do so. if the mechanics of the problem 

 are for a moment considered. 



The Chalk-stones, again, are quite different to ice-stones of all 

 kinds known to me, and the occasional scratches on the pieces of 

 chalk, which is a very soft substance, wonld be certainly caused 

 by any movement in which one stone rubbed against another. 



Again, as to icebergs, it is forgotten that it is only when grounded 

 dynamically that they act in the way suggested. "When they are floating 

 they are buoyed up by the water, and their pounding action must 

 be very slight. The intervention of coast-ice has been called in by 

 Mr. Mellard Eeade to account for the long chalk masses iu the 

 contorted drift at Cromer, but he overlooks the fact that similar 

 shifted masses occur in Rutland and Lincolnshire formed of the 

 local rocks there, where no old sea cliffs can be postulated. 



Lastly, the suggestion that rocks might under the influence of 

 alternate frost and thaw break up into such rubble as this, is again 

 completely contrary to all experience of Chalk known to me 

 (except on exposed cliffs, and even here very slightly indeed, as 

 we can see by walking along any of the great escarpments which 

 bound that deposit), nor can I see how the mechanical process could 

 begin or go on in a substance with the structure of chalk. Besides, 

 why should the frost have broken up the chalk in the low Fens 



