GREENLAND 205 



However, before turning to this new field there remains one other im- 

 portant body of facts which bears strongly upon the direction and amount 

 of movement of the Xorth American crustal sheet. 



GREENLAND, THE GREAT NORTHERN H0R8T 



If further evidence were needed to make sure that in the Tertiary 

 diastrophism North America moved toward the southwest — toward the 

 Pacific and the Tertiary fold mountains along its border — it may be 

 found in the remarkable relation of Greenland to North America. 



Suess remarks that *^^Greenland is a horst of the first order between two 

 or more sunken areas of different age'' (II, 294). But Suess' conclusion 

 was based mainly on different evidence from that offered here. 



A map of Greenland and its environs on a large scale shows some 

 remarkable characteristics in the outlines of the channels, straits, and 

 bays on its northern and western sides. These are shown fairly well in 

 figure 4. 



Amid such a tangle of irregular straits and channels as separate the 

 islands of the archipelago west of Greenland, it is quite surprising to find 

 a passage so straight and persistent as that which separates Grant Land, 

 Grinnell Land, and Ellesmere Land from the north part of Greenland. 

 It seems like a distinct rift-line, and the question arises as to the direc- 

 tion and amount of movement along it. It is quite different in character 

 from the great rifts or fault lines which Suess supposes to form the 

 sharply cut boundaries of the east and west sides of India, Africa, Mada- 

 gascar, and Greenland. It is a relatively narrow passage, and one seems 

 driven to the conclusion that the displacement along it was a horizontal 

 movement parallel with the rift. In looking for the direction, it seems 

 impossible to suppose Greenland to have moved toward North America 

 and the land on the west side of the rift relatively in the opposite direc- 

 tion, for in that case the movement would only have made Baffin Bay, 

 Davis Strait, and the Labrador Sea more narrow, and there would be no 

 reason to expect any element of parallelism in their sides. Besides, if 

 Greenland was formerly farther east the straight coast along the north 

 side of Peary Land would not necessarily be related to or determined by 

 the course of the rift ; it might be so related or it might not. Further, 

 there is no independent evidence that Greenland has moved at all, but in 

 the mountain knot of Alaska we have independent evidence that North 

 America has moved toward the southwest. Thus we may conclude, at 

 least provisionally, that it was North America that moved away from 

 Greenland, not vice versa. 



XV— Bull. Geol. Soc. Am.. Vol. 21. lOOlt 



