GEOLOGY 185 



Tertiary formations occur on the northwestern islands, on 

 the northern part of Ellesmere, as well as on the northern and 

 eastern parts of Baffin island. 



The former presence of a continental ice-cap is attested along 

 the northwestern shores of Hudson bay and in the southern part 

 of Baffin island, by the rounded and polished rock surfaces, 

 which are everywhere well marked by the ice striae, often in 

 several sets showing changes in the direction of the ice move- 

 ment. On the east side of Baffin the rock surfaces show signs of 

 rounding and smoothing by ice, but the striae are not well 

 marked, and the glaciation does not appear to have been nearly 

 so intense as to the south and westward. Passing northward up 

 the western side of Davis strait and Baffin bay the evidence of 

 intense glaciation becomes less and less, that on Ellesmere the 

 present condition of the local ice-covering would appear to 

 represent nearly as great an amount of glaciation as ever 

 occurred there. 



The sequence of earth movements and physical conditions, 

 read from the geological formations of the northeast, are as 

 follows : An ancient floor of crystalline rocks, largely of igneous 

 origin, represents the most ancient crust of the earth. These, 

 associated with ancient bedded deposits and cut by dark basic 

 intrusions of trap and allied rocks, were at a very early period 

 so crushed and foliated that it is now impossible to separate 

 them. Upon this ancient complex was laid down a series of 

 bedded deposits, chiefly sandstones and dolomites, associated 

 with contemporaneous traps, as may be seen along both the 

 shores of Smith sound. Following this came a great outburst 

 of granite and other acidic igneous rocks which, over large 

 areas, inclosed, penetrated, compressed and otherwise altered 

 the sedimentary deposits to such an extent that it is now impos- 

 sible to separate them from the older complex upon which they 

 were originally deposited. Only in a few comparatively small 

 areas were the conditions of the granite intrusion such as to 



