PHYSICAL CONDITIONS— PLEISTOCENE. 333 



have survived to the present in more southern and eastern regions, 

 while yet others are still represented in Europe by identical or 

 very closely allied species. Thus, according to Saporta, the 

 flora of the Pliocene is connected both with the past and the 

 present plant-life of Europe, while, at the same time, it has 

 relations with the floras of distant southern and eastern regions 

 — regions now separated by wide stretches of sea — America, the 

 Canaries, Eastern Asia, Japan, and China. 1 



During the same period the shores of North-western Europe 

 were washed by genial waters, in which lived many species of 

 molluscs, which must now be sought for in the seas of more 

 southern latitudes. All the palaeontological evidence, in short, 

 implies an equable and uniform climate which permitted the 

 intimate association in our continent of many types, both 

 animal and vegetable, now no longer able to co-exist at similar 

 elevations, or in one and the same latitude. 



The European area during the Pliocene Period appears at 

 one time to have been more extensive than it is at present, and 

 at another epoch to have experienced no inconsiderable amount 

 of submergence. The Adriatic and the Mediterranean rose high 

 upon the slopes of the Apennines — the valley of the Po forming 

 then a great arm of the sea which penetrated the mountain- 

 valleys of the Alps. The valley of the Arno, likewise, was under 

 water, so also were the lower reaches of the Ehone and extensive 

 tracts in the maritime district of South-western France. In 

 like manner Sicily was to some extent submerged, and the sea 

 overflowed wide areas in Belgium and the low-lying parts of 

 East Anglia. 



It is in the ancient deserted sea-bed of the Pliocene that we 

 detect that gradual deterioration of climate and approach of 

 colder conditions, which eventually culminated in the first 

 glacial epoch. In the older marine deposits of the English 

 Pliocene southern forms are present in great force, but they 

 gradually become less numerous as we follow them into the 



1 Compt Rend. Assoc, pour V Avarice, des Sciences, 1873, p. 461 ; see also Bull. 

 Soc. Oiol France, 3« Ser. t. i. p. 212. 



