268 THE CAUSES WHICH 



from amber-droppino- pine forests, the resort of small cieadae 

 and wayward bee-flies, long since buried beneath the Baltic and 

 Vistula sands, is due to the chill of the glacial period advancing 

 from the north-east, that scored and rounded the verdurous 

 mountains of Europe and America, coastward sinking in the 

 sea, with glacier or iceberg, leaving as witness huge moraine 

 heaps, entombing Arctic shells and boulders in our sunken valleys. 

 At this period we see the present fragile Arctic flora bud forth 

 on European areas. At Bovey Tracey, above the great series of 

 clays and lignites containing the Miocene plants, is a thick 

 covering of clay, gravel, and stones, evidently of much later 

 date. This also contains some plant remains ; but instead of figs, 

 cinnamons, and evei'green oaks, they are said to belong to the 

 dwarf birch of Scandinavian and Highland hills, and to three 

 willows, one of them being the little Arctic and Alpine creeping 

 willow. At the close of the glacial epoch the continents of the 

 northern hemisphere again rose from the waves, as may be 

 seen in the old raised beaches, strewn w^ith rounded, pebbles and 

 Arctic shells at different levels along the lines of coast and 

 estuaries. At this conjuncture the influx of a milder climate 

 drove the plants and insects of the two continents northward to 

 the Arctic region ; and forced them to climb in successive waves 

 alike the summits of the bare-backed Grampians and Scawfell, 

 or the newly-upheaved Alps, Pyrenees, and Apennines, where 

 saxifrages and gentians yet nestle with insects terrestrial in 

 more northern latitudes, such as Pachinoha alpina in Perth- 

 shire, Erehia Cassiope in Cumberland, the ringed Apollo butter- 

 flies and Chionobas Aello in Switzerland, or the golden Carabus 

 auratus in the Pyrenees. 



Fresh from the workshop of Providence, England and Ireland, 

 like all the islands bordering the great continents, now stand on a 

 bevelled plateau sunk from twenty to ninety fathoms, virtually a 

 submerged selvage of the European area."^ Around this the 

 plummet sinks 2,000 fathoms, and brings to light a line of 

 submerged cliffs bordered with beach shingles and shells. 

 During the Miocene, Pliocene, and again, in the opinion of 

 many geologists, at the close of the glacial period, this entire 



* Henry Walker, leisure Hour, Part 271, p. 421, July, 1874. 



