48 LINKS WITH THE PAST [ch. 



There are however some pre-Glacial plants, such as 

 the spruce fir (Picea excelsa), a cone of which is 

 shown in Fig. 3, B, the water chestnut, Trapa natans 

 (Fig. 4), and a few other species no longer repre- 

 sented in the British flora. The genus Trapa is 

 a striking exanii)le of a flowering plant which has 

 disappeared since the Tertiary period from many 

 parts of Europe, including England, most of Sweden, 

 and from several regions in northern Europe. It still 

 grows in a few localities in Switzerland and in some 

 of the Italian lakes. In pre-Glacial times the water 

 chestnut was widely spread from Portugal and England 

 in the west to Siberia in the east, and its hard four- 

 pronged nuts have been recorded from many post- 

 Glacial peat-moors in the north of Europe. 



From the so-called Cromer forest-bed and as- 

 sociated deposits on the Norfolk coast several 

 pre-Glacial plants have been obtained, indicating 

 a temperate climate during this phase of the 

 Pleistocene period. A few arctic species, such as 

 the dwarf birch and arctic willow obtained from the 

 deposits next above the Cromer forest-bed, herald 

 the near approach of glacial conditions. 



It may be remarked in passing that no satisfactory 

 evidence has been discovered in Britain of the 

 existence of man in this part of Europe in pre-Gla- 

 cial days : it is, however, believed that flints from 

 Tertiary strata on the continent show traces of human 



