16 



which began about 240,000 years ago and lasted tor some 

 160,000 years, does not appear to have been one unmterrupted 

 era of intense arctic chmate, but several milder periods inter- 

 vened, when the great ice-sheet retreated northwards and the 

 glaciers remained confined to the mountain-tops, till the 

 recurrence of the glacial climate again caused them to spread 

 to the lowlands and once more to push their way southwards. 

 During those mild inter-glacial periods, when the arctic forms 

 that inhabited this country had retreated wdth the glaciers, 

 animals such as the mammoth, rhinoceros, hippopotamus, 

 lion, tiger, bear, hyaena, &c., became inhabitants of Britain, 

 which was then connected with the continent of Europe 

 across what is now the German Ocean. The old inter-glacial 

 mammals — and probably Palaeolithic man was among them — 

 would have told of mighty revolutions in physical geography 

 could they have kept records, as our island, after they had 

 taken possession of it, became submerged beneath the sea to 

 an immense depth, till only the high lands appeared above 

 the waters, forming an archipelago. Then followed a final 

 return of glacial conditions, when the great ice-covering for 

 the last time enwrapped our country, which slowly rose from 

 the frozen ocean and once again became a portion of the 

 continent. As the more genial climate which has lasted to 

 our own times came on, the ice-sheet slowly disappeared ; 

 glaciers lingered for some time on our mountains, and finally 

 vanished, to return no more till the next glacial epoch. It 

 was during these continental states of Britain, when the 

 Thames was a tributary of the Ehine, that the country 

 became the home of those animals and plants the survivors 

 of which constitute our present fauna and flora, the sea 

 finally sweeping away the land connection and leaving our 

 island much as we now find it. 



The records of ** the great ice age " are more forcibly 

 impressed upon the mountainous districts of Wales, Scotland, 

 and the Lake District than in the southern portions of Eng- 

 land. The great submergence which preceded the last glacial 

 relapse left only the south of our island above the sea, and a 

 line drawn across the country from the mouth of the Thames 

 to the mouth of the Severn represents the southernmost 



