16 Barrett — Movements of the Strand Line 



per cent of the plants are boreal types. Only a few plants are 

 present out of the hundreds which constitute the flora typical 

 of Canada in the same latitude. On the other hand 35 per 

 cent of the plants of Newfoundland are southwestern types 

 and 7'7 per cent of these are plants characteristic of the 

 coastal plain of New Jersey and the south. Fernald shows, by 

 means of the evidence of the flora, the ineffectiveness of winds 

 and currents to transport across the Gulf of Saint Lawrence to 

 Newfoundland the typical Canadian plants, though the boreal 

 types may have entered across the comparatively narrow straits 

 which separate the island from Labrador. Fernald argues that 

 it would be still more difficult for winds and currents to act as 

 agents for the migration of the Coastal Plain flora. Not only 

 are the distances vastly greater, but the winds and currents 

 move actually in the wrong direction to carry plants from the 

 southwest. 



Migrating birds can hardly be invoked. The nearest land to 

 the southwest of Newfoundland is Cape Breton Island at a dis- 

 tance of 70 miles and many of the species of plants which are 

 concerned are rare and local at all points northeast of New 

 Jersey, a distance of over 850 miles. Studies of migrating 

 birds, especially in connection with the flora of the Faroe 

 Islands, have shown that they reach the end of their flights 

 with intestines empty. 



A remaining hypothesis is, that after the last retreat of the 

 ice, the Coastal Plain stood higher and offered northeastward a 

 line of passage broken only at a few places by channels of deep 

 water. A climate warmer than the present would favor this 

 migration of the flora of the southern Coastal Plain. An 

 elevation of at least 100 or better 150 to 200 feet, enduring for 

 some thousands of years, would apparently be needed to give 

 the necessary conditions for plant migration. An elevation of 

 200 feet would still involve, however, the crossing of 70 miles 

 of water in Cabot Strait. An elevation of the Coastal Plain 

 seems the readiest way of explaining the existence of such 

 isolated stations of southern plants as that of Magnolia virginica 

 at Cape Ann, Massachusetts, but migration from the southwest 

 is difficult to apply to Newfoundland. For this it may be 

 necessary to invoke another aspect of the same hypothesis of 

 elevation. 



The Great Banks extend 200 miles southeast of Cape Race, 

 to latitude 43 degrees. The Gulf Stream flows past not far 

 distant on the south and must serve to ameliorate the climate. 

 Nearly to the margin of the Banks the depths range no deeper 

 than from 30 to 40 fathoms. If, during and for a time follow- 

 ing glaciation, this region was above sea level and unglaciated, 

 it may have served as a haven of refuge for plants of the 

 Coastal Plain, requiring a temperate climate. 



