214 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



porphyrite ; the other, a slightly porphyritic alkaline rock, with pheno- 

 crysts of microcline and a grouudmass composed of microcline and 

 quartz in micropegmatitic intergrowth and an amphibole with the char- 

 acters of riebeckite. 



Massive granitic rocks were found at each anchorage between Hamil- 

 ton Inlet and Hopedale. At Sloop Harbor the hills are composed chiefly 

 of a coarse hornblende granite ; Jigger Island exhibits granitites similar 

 to that of the mainland; thirty miles farther north, on the mainland 

 opposite Conical Island, a flow-breccia of granitite cutting diorite proved 

 to be extensive. Associated with similar rocks are the only sedimentary 

 formations that were seen to the southward of Hopedale. 



Sedimentary rocks at Pomiadluk Point. — Pomiadluk Point forms the 

 extremity of a bold peninsula which projects northeastwardly from the 

 mainland in about 55° N. Lat. Stretching along the southeast side of 

 the peninsula for a distance of some five miles, is a broad bench from 

 two to three hundred feet in height and from one and a half to two 

 miles in breadth. On the southeast the bench falls into the sea quite 

 abruptly ; on the northwest it ceases at the foot of a steep ridge of 

 granitite that composes the main part of the peninsula. Barometric 

 readings on two different days accorded well in giving eleven hundred 

 feet as the elevation of a prominent summit of the ridge. Its average 

 height is not less than one thousand feet; toward Cape Strawberry it 

 rises to twelve hundred feet, and is thus the highest land encountered 

 on the coast between the Cape and the straits of Belle Isle. 



The glaciated ledges of the flat though hummocky bench have been 

 wave-swept during postglacial submergence and thus one can study the 

 rock-composition and structure with exceptional ease. The bench is 

 conterminous with a well exposed mass of metamoi'phic conglomerate. 

 Along four cross-sections about a half a mile apart, the sedimentary baud 

 was proved to be very homogeneous. In a silicious matrix, often highly 

 schistose, pebbles and boulders up to one or more feet in diameter are 

 embedded. They are composed of granitite, quartzite, vein quartz, 

 granite porphyry and metamorphic sandstone. They are almost always 

 considerably flattened, though the granitite pebbles have oftentimes so 

 far resisted the shear as to present still well-rounded outlines. The 

 schistose structure strikes steadily N. 15° W. ; its dip is variable but 

 steep and generally to the westward. Not allowing for duplication, the 

 thickness of exposed conglomerate measured on this secondary structure- 

 plane was estimated at eight thousand feet. On the west the conglomer- 

 ate becomes finer-crrained and for a distance of three hundred feet from 



