34-8 Mr. Lyell on the Boulder Formation, 



I have seen no kind of deposit now in progress precisely si- 

 milar in character to the till, except one, namely, the terminal 

 moraines of glaciers. These, as Charpentier has justly re- 

 marked, are entirely devoid of stratification, because the ac- 

 cumulation has taken place without the influence of any cur- 

 rents of water by which the materials would be sorted and 

 arranged according to their relative weight and size. Year 

 after year the ice, as it melts at the exti'emity of a glacier, adds 

 fresh mud, together with fine and coarse sand, gravel, and 

 huge blocks, to the moraine, all being carried to the same 

 distance*, without the least reference to the volume or specific 

 gravity of the component particles or masses. 



There can be no doubt that similar accumulations must 

 take place in those parts of every sea, where drift ice, into 

 which mud, sand, and blocks have been frozen, melts in still 

 water, and allows the denser matter to fall tranquilly to the 

 bottom. The occasional intercalation of a layer of stratified 

 matter in the till, or the superposition or juxtaposition of the 

 same, may be explained by the existence or non-existence of 

 currents, during the melting of the ice, whether successively 

 in the same place or simultaneously in different places. 



It is, I believe, a common error of those who are not un- 

 willing to admit the agency of ice in reference to the larger 

 fragments of transported rock, to forget that what carries 

 heavier masses from place to place must unavoidably convey 

 a much larger volume of lighter and finer materials. 



Having offered these preliminary remarks, I shall proceed 

 to describe in detail some of the appearances which present 

 themselves to one who travels along the coast from Has- 

 borough to Weybourne. The section of the mud cliffs begins 

 at the more southern of the two lighthouses about a mile and 

 a half south of Hasborough. The cliffs here, which are be- 

 tween sixteen and twenty feet in height, are composed generally 

 of a mass of blue clay covered with yellow sand, the clay and 

 sand being both stratified in some places with great regularity, 

 but in others the clay or mud is quite unstratified. Included 

 in this till I found pieces of unrounded white chalk, angular 

 chalk flints, fragments of argillaceous limestone (lias?), blocks 

 of dark greenstone, and other rocks. There are also inter- 

 spersed pieces of shells, apparently belonging to Cyjprina, Car- 

 dium, Mactra, and Tellina, such as might have been derived 

 from the denudation of the Norwich crag. At some points 

 where stratified clay reposes on the till, the surface of the latter 

 is very uneven, and was evidently so when the superior de- 

 posit was thrown down upon it. Examples of intercalation of 



* j^nn. des Mines, torn. viii. 



