of Lake Superior. 247 



there issues into the water a number of angular masses of that sub- 

 stance, fitting rudely into each other. Small ramifying veins of 

 red feldspar are almost universal ; and they are often accompanied 

 by white calcspar. A remarkable circumstance in these veins is 

 the prismatic forms into which their more exposed portions are 

 sometimes divided ; these outer parts being then composed of ir- 

 regular columns piled one above another, more or less horizontally, 

 and crosswise to the direction of the vein. These columns are of 

 four unequal sides, and are from eight to twenty inches in dia- 

 meter. The upper layer (or more) is often displaced ; the set next 

 beneath fit closer to those below, while the inferior part of the 

 latter may not be completely divided. The separation thus be- 

 comes less and less complete downwards until massiveness is 

 established. This is seen in all the rocks enumerated at the be- 

 ginning of these remarks, but best in the Pay Plat, in an islet 

 near the east end of St. Ignatius, and near Caps Verd. More 

 commonly the division into columns is incomplete in the upper 

 layer; then the vein seems paved with oblong square masses, 

 lying transversely with their edges upwards. 



Greenstone takes the place of the granite, just described, from a 

 promontory among some isles about two miles south of the Peek 

 River, to about five miles N.W. of that river. I am unable 

 to state minutely the circumstances under which the junction 

 occurs. 1 passed within 100 yards of it. The greenstone of this 

 small district is quite that of Michipicoton ; — like it, massive, but 

 here and there shewing traces of a stratification ; running N.E. 

 and E.N.E. ; varying in its colour and composition by irregular 

 patches, and sometimes in sets of layers ; that of the north angle 

 of Peek Bay has a slightly-striated structure, with white crystalline 

 spots of quartz sprinkled over it, and appears in round unstratified 

 hummocks, of smooth and glazed surface. On the south-side of 

 this bay the greenstone is traversed by a well-marked trappose 

 vein. On the main shore immediately north of Peek Bay it is only 

 in a few low detached patches. I am informed it contains seams 

 of chlorite earth. 

 'I'his rock is succeeded westward* by sienite in diversified forms; 



