282 THE GEOLOGY OF THE LABRADOR COAST. 



partly rounded and contained rolled quartz pebbles, one 

 being ovate and nearly two inches long. This syenitic 

 gneiss was evidently an altered conglomerate. 



Thje syenite is the same as occurs on the coast of the St. 

 Lawrence River, and while of the same color as that of 

 the Maine and Nahant syenite, differs in its greater hard- 

 ness and in the absence of black hornblende. It is com- 

 posed of a flesh-red orthoclase or potash feldspar and a 

 smoky and glassy quartz with minute particles of horn- 

 blende disseminated sparsely through the mass. It is 

 exceedingly tough and durable, as evidenced by the lofty 

 capes and islands standing far up above the gneiss rocks 

 spreading around the base of the overflows. 



At the northern end of the island the syenitic gneiss 

 dips under the trap in a southeasterly direction at an 

 angle of 50°. On an island a few rods farther to the 

 north the gneiss assumes its usual character, being 

 banded with light and dark strata, and has the general 

 N. N. E. strike and dip indicated above. 



At Square Island, which lies at the mouth of a deep 

 bay just north of Cape St. Michael occurs in large, 

 conical hills what I judge to be the great anorthosite for- 

 mation of Logan and Hunt, composed of large, crystal- 

 line masses of labradorite, with a little vitreous quartz, 

 and coarse, crystalline masses of hornblende. The lab- 

 radorite is of a smoky color, very lustrous, translucent 

 and opalescent, with cleavage surfaces often two inches 

 in diameter, and on some of the faces presents a greenish 

 reflection. This is but a slight approach to the rich 

 blue reflections of the precious labradorite which I have 

 seen only at Hopedale, where we obtained specimens 

 brought from the interior by the Eskimos which 



