VEGETABLE COLONIZATION. 233 



According to Mr. Forbes, the appearance of Armorican plants in 

 Devonshire, Cornwall, and the southeast of Ireland, connects itself 

 with the existence of this vanished continent. The southern physi- 

 ognomy of these vegetables strikes him as indicating a milder climate 

 than now exists ; yet nothing forbids our considering this migration 

 as cotemporaneous with the Germanic inroad, if we refer it to the 

 period when France and England were not yet separated. 



The immersion of this great continent was followed by a very dis- 

 similar era, during which the temperature of the air was lower than 

 at present. It was during this period, according to Mr. Forbes, that 

 the migration of Arctic plants, which still cling to the mountains of 

 Scotland and England, took place. The proofs of a glacial era, imme- 

 diately preceding our own, abound throughout the north of Europe. 

 I shall not speak here of the numerous traces of ancient glaciers, 

 observable in the mountains of England and Ireland, but restrict 

 myself to arguments drawn from the animal kingdom.* 



The larger part of the British Islands is covered with a moveable 

 deposit formed of transported materials^ which the English geologists 

 have designated by the name of drift. In two-thirds of England and 

 Ireland lying towards the north, and throughout Scotland, this drift 

 contains the remains of animals which are no longer found alive 

 except in the depths of the Frozen ocean, on the coasts of Iceland and 

 Greenland. Their enumeration would detain us too long. I shall 

 content myself with instancing the right whale, the cachelot, (sperm 

 whale, t) the bala3noptera, the narwal, a fish of the seas of Green- 

 land, and a large number of shells which are still seen existing in 

 those latitudes. During this period, then, England was in part 

 covered by waters whose temperature was similar to that of the frozen 

 ocean. Not only the plains, but also the lower parts of the moun- 

 tains, formed the bed or the borders of that ocean ; for in Wales beds 

 of gravel, sand, and shells, are found at an elevation of 1,476 feet 

 above the level of the sea. At that epoch England and Scotland, 

 instead of a continuous territory, presented but a group of large and 

 small islands. The mountains of Scotland, Cumberland, and Wales, 

 alone raised themselves above the waves. A climate analogous to that 

 of Iceland prevailed in this archipelago ; the summits of the mountains 

 were covered with eternal snows like that of Hecla, and numerous 

 glaciers descended along the valleys to the borders of the sea. The 

 plants of Greenland, Iceland, and Norway, borne by the currents or 

 transported by the floating ice, drifted on these islands, where they 

 met with a climate but little different from that of their native home. 

 This transportation of plants by drifting ice is no gratuitous hypo- 

 thesis. Navigators of the polar seas have often encountered ice fields 

 loaded with an enormous mass of mingled sand and gravel, on which 

 plants were vegetating, as on the median moraines of the glaciers of 

 the Alps, and which being stranded on some distant coast would there 

 de])osit the plants which afterwards spread themselves in the country. 

 These Arctic vegetables, Mr. Forbes tells us, have not disappeared 



"' See, on this subject, ' ' Researches on the glacier period and the ancient extension of the 

 glaciers of Mont Blanc from the Alps to the Jura. — {Revue d(s deux Mondes, tome XVII, 

 p. 919. March, 1847.) 



f This species is not conlined to the northern seas. — Translalor. 



