42 Origin of the British Flora. 



Remains of this boreal fauna and flora have now been 

 found at several places in the south of England. A large 

 assemblage of Arctic mammals has been discovered near 

 Salisbury, and it includes such thoroughly boreal forms as 

 the Musk Ox, Arctic Fox, and Lemmings. Even in what 

 is now one of the warmest parts of our Islands, Arctic 

 plants occur in the fossil state ; for Bovey Tracey, in 

 Devon, yields the Dwarf Birch, and the Bearberry. This 

 leaves no place of retreat within these islands for the 

 Temperate animals and plants. All Ireland was glaciated, 

 so nothing could live there, except perhaps a few Arctic 

 plants on the mountain-tops. All England was under ice, 

 except the extreme south ; and there the climate was too 

 cold for temperate plants to live. It may be suggested 

 that the Scilly Islands were warmer, and perhaps they 

 were somewhat better than Devon and Cornwall. But this 

 will not account for the preservation of the Lusitanian 

 Species, for most of them are not found on the Scilly 

 Islands, and plants like the Arbutus would be killed by a 

 climate only slightly more severe than that now found in 

 Ireland. 



After the passing away of the ice there was a return to 

 genial conditions, which lasted so long that during this 

 ' Inter-glacial ' period a series of physical changes took 

 place, and there was time for the Arctic species to die out 

 and for a large Temperate fauna and flora to occupy the 

 country. We do not yet know the history of some of the 

 stages, as there are several gaps in the record ; the changes, 

 however, were slow and gradual, allowing time for valleys 

 to be deepened and again silted up, for sea-cliffs to be cut 

 back, and for plants to spread far and wide over new 

 districts. During the greatest intensity of the cold, as we 

 have shown, there seems to have been a submergence of a 

 few feet. Then comes a break for which the records have 



