244 NEOZOIC TIME. [CHAP. XII. 



west. There is evidence of these streams coming from that 

 direction in the circumstance that in the Crag at Norwich, 

 Lias Ammonites, Mountain Limestone corals, besides the 

 many fossils from the Chalk, are found. I have found also 

 at the base of the Crag at Weybourn a fragment of fos- 

 siliferous Kimeridge Clay, and in the Norwich Crag a 

 fragment of an encrinital column similar to one I have 

 seen in the Red Crag of Sutton, in which latter also occur 

 Belemnites, Ammonites, Ostrece, and Terebratulce, from 

 various Secondary rocks, together with fragments of chert 

 from the Lower G-reensand, while the occurrence of the 

 fragments of red granite points to transport from still 

 more distant localities" (op. cit., p. 476). 



The Chillesford sands and clays, and the laminated clays 

 which overlie the Norwich Crag, possibly indicate a further 

 submergence, for the sands are finer and less ferruginous, 

 the clays are grey and laminated, and the bivalve shells in 

 them frequently occur in undisturbed position with united 

 valves. At the same time there is a diminution in the 

 number of southern mollusca and a prevalence of northern 

 forms, facts which prove the waters to have become much 

 colder, and suggest that the quantity of ice in the Arctic 

 regions had greatly increased. 



The Weybourn Crag mentioned above is of about the 

 same age as the Chillesford Beds, though possibly a little 

 newer, as in it Tellina balthica first appears, and the per- 

 centage of northern forms is increased to 16 per cent., that 

 of the Chillesford and Norwich beds being only 8 or 9 per 

 cent. 



Shelly sands (Scaldisien of the Belgian geologists) simi- 

 lar to our Eed Crag cover a considerable area in the north 

 of Belgium, see map, fig. 7, and they extend northward 

 through Holland beneath the Pleistocene deposits of that 

 country ; in the deep boring recently made at Utrecht 

 their thickness was found to be no less than 270 feet, the 



