286 THE GEOLOGY OF THE LABRADOR COAST. 



fine, compact dolerite, breaking with a conchoidal frac- 

 ture and metallic ring, and contains much iron. The 

 mass is two hundred and fifty-five feet high on Henley 

 and Castle Islands, and consists of two layers of vertical 

 columns. West of these basaltic rocks, on the opposite 

 side of the harbor, is a large trap overflow forming a hill 

 over three hundred feet high, and apparently of the 

 same age. It should be remarked that the two la)'ersof 

 basalt representing successive overflows incline at a very 

 slight angle towards the S. W. The third mass of ba- 

 salt is seen rising out of the ocean a few miles northerly, 

 nearly in a line with the basalt of Henley Harbor. 



Dykes of this age were likewise seen at Strawberry 

 Harbor, Cape Webuc, and at Hopedale, intersecting the 

 Laurentian gneiss and syenite. Their age is plainly an- 

 terior to the deposition of the undisturbed Cambrian, 

 " primordial " strata at Anse-au-Loup, and on the New- 

 foundland coast opposite. 



Domino Gneiis. — A system of lij'-ht-colored gneiss and 

 trap rocks which lie in a depression of the Laurentian 

 rocks, about one hundred and twenty-five miles long and 

 probably twenty-five miles broad, stretching along the 

 coast between Domino Harbor and Cape Webuc, agrees 

 with the " Domino Gneiss" of Mr. Lieber. 



At Domino Harbor in lat. 53° 30", these rocks attain 

 their greatest development, occurring as a slightly schis- 

 tose, light-colored gneiss, the base of which is a white 

 granular vitreous quartz, with speckles of black horn- 

 blende, with a few particles of a lilac-colored mica. 

 There are also minute rude crystals of yellow garnet, or 

 cinnamon stone, disseminated through the mass. No 

 feldspar was detected in this rock. In some places the 



