132 



NORFOLK DRIFT AND 



[Ch. XI. 



drift is wanting, as, for example, in the Wealds of Surrey, Kent, and 

 Sussex. 



Norfolk drift. — The drift can nowhere be studied more advantageous- 

 ly in England than in the cliffs of the Norfolk coast between Happisburgh 

 and Cromer. Vertical sections, having an ordinary height of from 50 to 

 *70 feet, are there exposed to view for a distance of about 20 miles. The 

 name of diluvium was formerly given to it by those who supposed it to 

 have been produced by the violent action of a sudden and transient 

 deluge, but the term drift has been substituted by those who reject this 

 hypothesis. Here, as elsewhere, it consists for the most part of claj'-, 

 loam, and sand, in part stratified, in part devoid of stratification. Peb- 

 bles, together with some large boulders of granite, porphyry, green- 

 stone, lias, chalk, and other transported rocks, are interspersed, especially 

 through the till. That some of the granitic and other fragments came 

 from Scandinavia I have no doubt, after having myself traced the course 

 of the continuous stream of blocks from Norway and Sweden to Den- 

 mark, and across the Elbe, through Westphalia, to the borders of Hol- 

 land. We need not be surprised to find them reappear on our eastern 

 coast, between the Tweed and the Thames, regions not half so remote 

 from parts of Norway as are many Russian erratics from the sources 

 whence they came. 



White chalk rubble, unmixed with foreign matter, and even huge 

 fragments of solid chalk, also occur in many localities in these Norfolk 

 cliffs. No fossils have been detected in this drift, which can positively 

 be referred to the era of its accumulation ; but at some points it overlies 

 a freshwater formation containing recent shells, and at others it is blended 

 with the same in such a manner as to force us to conclude that both were 

 contemporaneously deposited. 



Fig. 116. 



The shaded portion consists of Freshwater beds. 

 Intercalation of freshwater beds and of boulder clay and sand at Mundesley. 



Tins interstratification is expressed in the annexed figure, the dark mass 

 indicating the position of the freshwater beds, which contain much vege- 



Fig. 117. 



Paludina rnarginata, Michaud. (P. minuta, Strickland.) 

 The middle figure is of the natural size. 



