Ch. XII] NORFOLK DRIFT. 1(31 



and clay, the shells being all of recent species; fifthly, firmly lamin ate d 

 blue clay without fossils, on which rests the boulder clay of the glacial 

 period, from 20 to 80 feet thick, with far-transported erratics, some of 

 them polished and scratched ; sixthly, contorted drift ; seventhly, super- 

 ficial gravel and sand. 



In the Norwich Crag above mentioned, which will be described in 

 chap, xiii., there is a small mixture (about 12 per cent.) of extinct 

 species of shells, but in the overlying formations, beginning with the 

 forest bed, the species are identical with those now living, and it is 

 remarkable that, while the plants in the forest bed and lignite are such 

 as now exist in Europe, and are nearly all of them indigenous in Great 

 Britain, the mammalian fauna contains many conspicuous species 

 which no longer survive in any part of the globe. Among these last, 

 as appears from the rich collections of Messrs. Gunn and King, are no 

 less than three species of elephant, namely, first, the mammoth, E. 

 primigenius ; secondly, the elephant first observed in the Yal d'Arno, 

 E. meridionalis, Nesti ; and, thirdly, E. antiquits, in smaller numbers 

 than the two former. These are accompanied by Rhinoceros etruscus 

 (a species first obtained from beds of the same age near Florence), 

 Hippopotamus major, the common pig, a species of horse and of bear, 

 the common wolf, a bison, the large Irish deer, the reindeer, and other 

 deer, the common beaver, besides a larger extinct species, also the 

 walrus, narwhal, and some others. They amount in all to about 20 

 species, of which rather more than half are extinct. 



It will be seen in the next chapter that the shells of some of the 

 latest deposits of Norwich Crag show that great cold prevailed in 

 the British seas before the close of the Newer Pliocene period ; when 

 we speak, therefore, of the vegetation and quadrupeds of the Cromer 

 forest being pre-glacial, we merely mean that they preceded the era 

 of the general submergence of the British Isles beneath the waters of 

 the glacial sea. That they were anterior to that submergence may 

 be inferred from the superposition on the forest and lignite beds of 

 the vast load of boulder-clay above alluded to, which contains far- 

 transported blocks, some of Scandinavian origin, and probably floated 

 from the north when Norway and Sweden were as much covered with 

 ice as the modem continent of Greenland. Other portions of the till 

 may have come from the northwest, as they comprise the wreck of 

 the Cretaceous, Oolitic, and older British formations. 



The fluvio-marine series affords distinct evidence of several alterna- 

 tions of fluviatile, marine, and terrestrial conditions. Besides the 

 forest bed, for example, Professor Philips has observed at one point 

 a growth of land-plants in an erect position, at a higher level, and 

 Mr. Kino- has found intercalated beds in which bivalve shells, such 

 as Mya truncata, are so placed erect in the loam with their siphun- 

 cular ends uppermost, as to show, as unmistakably as does the erect 

 position of the trees with their roots still fixed in their original soil, 

 that they lived on the spot where they are now entombed. It was 

 11 



