PAST GEOGRAPHICAL MUTATIONS 19 



physical and climatal changes occurring contempo- 

 raneously in other parts of Europe, together with the 

 probable effects of such changes on the co-existent 

 faunas and floras. For this latter information especially 

 I am chiefly indebted to the profound researches of 

 Professor Geikie, one of the highest authorities on the 

 subject. 



We may begin our cursory sketch with the gradual 

 passing away of the second glacial period — with the 

 retreat of the ice-sheets from North-western Europe and 

 the melting of the glaciers in the valleys of the Alps 

 and other mountain chains of Central and Southern 

 Europe. We remark the northern advance of plants 

 and animals, their invasion of alpine regions, and their 

 replacement by more temperate species from still 

 more southern areas, emigrating northwards with the 

 amelioration of climate. Dense forests gradually spread 

 northwards and up the mountain sides, under the de- 

 velopment of favourable climatic conditions ; and a 

 mixed and luxuriant flora slowly covered the long- 

 desolated land. Once more the mammals emigrated 

 northwards, many passing from Africa to Europe by 

 land connections between Italy and Tunis, and Spain 

 and Barbary ; southern and temperate forms com- 

 mingling and ranging from the shores of the Mediter- 

 ranean up to the north of England, and even into 

 Scotland ; large carnivores frequenting the forests and 

 bears the caves. " If laurels, fig-trees, and judas-trees 

 grew side by side in Northern France with the sycamore 

 and the ash, and in low-lying countries on the borders 

 of the Mediterranean with pines, oaks, beeches, pop- 

 lars, and elms, so also," writes Professor Geikie, " were 



