RELICS OF MAN IN THE GLACIAL PERIOD. 291 



Professor Boyd Dawkins attempts to reduce the diffi- 

 culty by supposing that the Glacial epoch was marked by 

 the occurrence of minor periods of climatic variation, dur- 

 ing which, in comparatively short periods, the isothermal 

 lines vibrated from north to south, and vice versa. In this 

 view the southern species gradually crowded upon the 

 northern during the periods of climatic amelioration, 

 until they reached their limit in central England, and 

 then in turn, as the climate became more rigorous, slowly 

 retreated before the pressure of their northern competitors. 

 Meanwhile the hyena sallied forth from his various caves, 

 over this region, at one time of the year to feed upon the 

 reindeer, and at another time of the year upon the flesh 

 of the hippopotamus, in both cases dragging their bones 

 with him to his sheltered retreat in the limestone caverns * 

 which he shared at intervals with palaeolithic man. 



The theory of Mr. James Geikie is that the period, 

 while one of great precipitation, was characterised by a 

 climate of comparatively even temperature, in which there 

 was not so great a difference as now between the winters 

 and the summers, the winters not being so cold and the 

 summers not so hot as at present. This is substantially 

 the condition of things in southern Alaska at the present 

 time, where extensive glaciers come down to the sea-level, 

 even though the thermometer at Sitka rarely goes below 

 zero (Fahrenheit). It is, therefore, easy to conceive that 

 if there were extensive plains bordering the Alaskan archi- 

 pelago, so as to furnish ranging grounds for more south- 

 ern species, the animals of the north and the animals of 

 the south might partially occupy the same belt of terri- 

 tory, and their bones become mingled in the same river 

 deposits. 



In order to clear the way for either of these hypotheses 

 to account for the mingling of arctic and torrid species 



* Early Man in Britain, p. 114. 



