260 bulletin: museum of comparative zoology. 



A]on<>- the line on which our observations were made, there has been 

 unequal positive uplift of the earth's crust. The force responsible for 

 great piece of work has been applied locally and in varying degree. 

 The result is that to-day the actual distance from the centre of the earth 

 of every point on that line is greater than it was at the close of the 

 glacial period. 



The coastal belt shows a degree of elevation considerably less than 

 that demonstrated for the region east and southeast of James Bay. Sup- 

 plementing the data of Low's and De Geer's maps with the writer's 

 observations on the northeastern coast, oue is led to the conclusion that 

 the uplift of the glaciated tract of this part of America has been greatest 

 near the region of the central neve. 1 The result is to strengthen De 

 Geer's parallel between the postglacial behavior of the earth's crust in 

 northeastern North America and in northwestern Europe. The bearing 

 of this conclusion on the theory of isostasy is obvious. Perhaps the re- 

 latively great uplift of Newfoundland is connected with the local charac- 

 ter of its glaciation, which, according to Chamberlain, was not due to an 

 extensiou of the ice-fields of the mainland. 2 



Boulder Barricades. — There is not wanting an indication that on 

 the Labrador coast, at least, the land is higher to-day than in any other 

 part of postglacial time. Wherever the shore slopes are not too steep, the 

 coast is belted with lines of innumerable large boulders visible between 

 low and half tides. These accumulations may be called " barricades." 

 The name is recognized as appropriate by any one who attempts to land at 

 low water by forcing a small boat through a gap in the nearly submerged 

 wall of boulders. The barricade is situated twenty to one hundred or 

 more feet from the shore according to the slope of the foreshore ; the 

 distance is greater as the slope is the more gentle. Plate 9 gives a 

 typical view of oue seen at Ford Harbor. Lyell long since figured an 

 example in the " Principles of Geology (ed. 11, 1892, Vol. I. p. 381). 



Of particular significance is the fact that, in practically every case 

 where one of these accumulations was examined, it proved to be com- 

 posed essentially of large glacial erratics. These are believed, in most 

 cases, to have been derived from the wave-swept zone immediately above. 

 As the land emerged, the boulders were dragged down in the undertow 

 and lodged just below the level where the surf could move them. The 

 relative absence of boulders between the shore and the barricade is also 

 explained in part by the action of coast-ice, which floats off such boul- 

 ders when the ice-foot breaks up. If the boulders happened to be 



1 Proc. Bost. Soc. Nat. Hist., 1892, vol. 25, p. 464. 



2 Bull. Geol. Soc. Amer.,1894, vol. G, p. 407. 



