0 F T H B ROOKS OF LAKE SUP E 11 I O R. 



235 



248. Basaltic rock — colour, grajdsh black; very fine-grained ; homogeneous; no 

 appearance of crystallization ; contains veins of calcareous spar. 



249. Calcareous spar — from a vein in No. 248 ; the sides of the vein lined with 

 a hard, yellow material, derived, probably, from decomposed felspar. 



250. Metamorphosed siliceo-argillaceous shale — colour, purplish; very rough, un- 

 even fracture; porphyritic, like No. 251. In some places presents the appearance 

 of a fine breccia, well cemented by material of the same character as the fragments. 



251. Siliceo-argillaceous shale — highly metamorphosed, and changed to a quartzose 

 porphyry. The beds are the same as No. 244. Contains numerous crystals of 

 felspar, mostly four-sided prisms, and in a decomposing state ; and also many grains 

 and incrustations of oxide of manganese. 



252. Metamorphosed siliceous shale — finely laminated ; colour, purplish red ; 

 porphyritic ; numerous prisms of decomposing felspar, and some few of quartz ; very 

 hard and brittle. 



253. Basaltic rock — fine-grained ; fracture, smooth ; colour, greenish black. 



254. Breccia — made up of fragments of sandstone and shale, and strongly ce- 

 mented ; colour, dark red ; full of cells and cavities, which contain mostly calca- 

 reous spar, and a green incrusting mineral, probably silicate of iron. 



255. Same as No. 254, but not so much altered. 



256. Basaltic rock — fine-grained ; black, with a reddish tint. 



257. Basaltic rock. 



258. Basaltic rock. Same as No. 256. 



259. Brecciated conglomerate — composed, principally, of fragments and pebbles 

 from the amygdaloidal beds of volcanic grit, and the earthy red shale-beds ; mostly 

 angular, but with many rounded ones. These are cemented together by earthy 

 matter which has been partially fused. The cement is amygdaloidal, and contains 

 carbonate of lime with some zeolites. Colour, dark purple, and mottled. Has been 

 subjected to a high degree of heat. 



260. Same as the conglomerate No. 246, and the coarse siliceous beds (No. 245) 

 associated with it. Some of the shale-beds appear to have slipped over one another, 

 producing a planished surface, with numerous green stains, produced, probably, by 

 silicate of iron. A good deal of chlorite (?) is found in the body of the rock, in 

 streaks and in small cavities. Bears great resemblance to the green schists of St. 

 Louis River. 



261. Basaltic rock — colour, dark purple ; homogeneous; very compact; fracture 

 smooth. At some points the basalt has penetrated the sedimentary deposits for 

 some distance, and shows itself in small patches. 



262. Same as No. 251 and No. 41 of Pigeon River. This rock, which, at the 

 contact of the two, takes on the character of No. 261, is composed of numerous 

 lumps and crystals of red felspar, cemented by quartz, and on smooth surfaces, pre- 

 sents a highly porphyritic appearance. The predominant colour of the whole rock 

 is deep flesh-red. I consider it to be the same as the " Great Palisade" Rock, and 

 to have been altered from the siliceous and argillo-siliceous shales so well developed 

 on the Wisacode - River. The rock is highly crystalline, and the degree of meta- 

 morphosis is probably the highest of which it is susceptible. 



