216 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



lacing network of granitic and trap dikes as well as by pegmatitic, aplitic 

 and quartz veins. On the east side of the bay opposite Summer Cove, 

 similar quartzites dipping 50° S. 70° E. occupy a second belt along the 

 shore of about the same dimensions as those of the western shore-belt, 

 ■ting that the sediments are here exposed for only three hundred 

 yards. At either end the belt is cut off by hornblende granite and 

 hornblende gneiss on which the quartzite seems to have been deposited. 

 All these rocks are cut by numerous wide and conspicuous dikes of 

 augite porphyrite and squeezed amphibolitic trap. At the head of the 

 bay, quartzites dipping 55° S. 35° W. were seen on a low spur projecting 

 into a boulder-covered tidal flat. 



In this case, as at Pomiadluk Point, diligent search failed to disclose 

 fossiliferous evidence as to the horizon of the stratified deposits ; at 

 both localities there is the same general relation between eruptives and 

 sediments, suggesting that the latter are, roughly at least, contempora- 

 neous deposits. 



Threading the maze of islands extending from Aillik Bay to Hope- 

 dale, no halt was made and no sampling of the coast geology could 

 be carried on. From the somewhat monotonous character of the 

 island-zone both as to color and form, it seemed to be composed of 

 the coarse biotite gneiss which characterizes the rugged hills about 

 Hopedale. Trap dikes were always in the view. Striped Island, 

 twenty miles E. S. E. of Hopedale, owes its name to the curious con- 

 touring habit of twelve great dikes that have penetrated the granitic 

 boss-like island along a nearly horizontal system of master-joints. 

 They are now visible all around the clean-swept island but are par- 

 ticularly conspicuous on the west side for a distance of a half mile. 

 At Hopedale, the wonderfully contorted gneiss, which is penetrated 

 by numerous diabase dikes, has an average strike of N. 55° W. 

 Thence northward, the archipelago of ragged sub-conical islands of the 

 same gneissic composition extends with northwest trends to Ford 

 Harbor on the east end of Paul's Island. Anchoring at Quirk Tickle, 

 fifty miles north of Hopedale, wc found the banded biotite gneiss with 

 northwest strike and indistinguishable from the rock at Hopedale. 

 Extending as it does a distance of at least one hundred and twenty 

 miles along the coast, the Hopedale gneiss is one of the most im- 

 portant members of the whole crystalline complex. 



The Nain gabbros. — The Hopedale gneiss underlies the eastern end 

 of Paul's Island, but a few miles west of Ford Harbor, it comes in con- 

 tact with the famous anorthosite and allied gabbro whence is derived the 



