T H B II 0 C K S O F 



L A K E 



SUPERIO R. 



243 



porosity renders it very light. Longer-continued or more energetic metamorphic 

 agency, would probably have converted it into a rock like No. 117. 



389. A vein in No. 388 — quartzose, granular; colour, dirty yellowish gray; fine- 

 grained ; a good many grains of felspar, and many of a green colour, too small to 

 be determined ; has a banded appearance on fractured surfaces. A few small gravel- 

 stones are contained in it. 



390. Metamorphosed sandstone — but little altered; colour, red; like the fine- 

 grained argillaceous beds of the south shore of the Lake. Contains nests of quartz 

 crystals. 



391. Dolerite — very fine-grained ; minutely crystalline ; colour, very dark gray. 

 Weathers with a smooth, light-gray surface, covered with a thin crust. Sometimes 

 the weathered surface is black. 



392. Basaltic rock — colour, gray ; homogeneous ; shows no appearance of crystal- 

 lization ; fracture, even, inclined to be conchoidal. 



393. A seam at the junction of Nos. 390 and 391 — contains angular fragments of 

 No. 391, the interstices being filled with calcareous spar and zeolites. One side of 

 the seam appears to have been rubbed smooth by a vertical motion. 



394. Amygdaloidal nests in No. 390 — the cells filled with globular and kidney- 

 shaped nodules of calcareous spar, the nodules being incrusted with a thin coating 

 of green carbonate of copper. Some of the cells are filled with carbonate of copper, 

 and a few grains of the same mineral are scattered through the base of the amyg- 

 daloid. 



395. Tourmaline — in nests in No. 390; colour, brown and brownish red; in 

 long crystals, penetrating calcareous spar. Many of the crystals are green exter- 

 nally. 



396. Quartz crystals — in druses in No. 390; some of them are large, and all are 

 incrusted with oxide of iron. 



397. Epidote — associated with calcareous spar; in metamorphosed sandstone con- 

 glomerate. 



398. Vein in metamorphosed sand-rock — resembles No. 389. Contains native 

 copper and prehnite, with numerous grains of native copper disseminated through 

 it, The veinstone is quartzose. 



399. Has a syenitic appearance — but is probably a volcanic tufa; colour, red; is 

 made up' of fragments of felspar and hornblende crystals, enveloped in a very calca- 

 reous paste. 



400. A tolerably fine-grained calcareous rock — highly metamorphosed ; resembles 

 aphanite ; contains fragments of clay-slate. 



401. Metamorphosed siliceo-calcareous shale — amygdaloidal; colour, purplish gray; 

 belongs to the amygdaloidal earthy beds. The cells are filled with carbonate of 

 lime in kidney-shaped nodules, with a thin coating of chlorite next the sides of the 

 cells. 



402. Argillo-calcareous shale, highly metamorphosed ; amygdaloidal ; cells nume- 

 rous, and filled with carbonate of lime ; colour, purplish gray ; decomposes easily, 

 when exposed to the weather. This rock is associated with a syenitic-looking tufa- 

 ceous porphyry, which contains much flesh-coloured felspar, in irregular, fragmen- 



