OF THE ROCKS OF LAKE SUPERIOR. 



245 



424. Metamorphosed clay-slate — has a basaltic appearance in the vicinity of trap 

 dikes. 



425. Greenstone — slaty. Bears considerable resemblance to hornblende schist. 



426. Porphyritic greenstone — coarsely crystalline ; bears great resemblance, at 

 some points, to petrosilex. 



427. Basaltic rock — colour, grayish to black, with a light tint of red ; fine- 

 grained. 



428. From a vein — contains calcareous spar, some zeolites, and numerous small 

 fragments of rock. This vein is situated between the walls of a trap dike and the 

 sedimentary rock. 



429. Vein — contains calcareous spar, yellow iron pyrites, and fragments of rock. 



430. Vein — contains calcareous spar, zeolites, and sulphate of barytes. 



431. Dolerite — fine-grained; minutely cry stalline. 



432. Greenstone. 



433. 434. Greenstone. 



435. Slaty greenstone — grayish-coloured; amygdaloidal, the cells filled with zeo- 

 lites ; contains much epidote in grains and amygdules. Some of the beds very 

 quartzose, and might be set down as quartz-rock. 



436. Greenstone. 



437. Metamorphosed shaly sandstone — reddish-coloured ; amygdaloidal, the cells 

 filled with epidote. Resembles some of the grits in the neighbourhood of Inaonani 

 and Kawimbash Rivers. 



438. Sandstone — somewhat shaly ; colour, light gray, with a reddish tint, derived 

 from numerous grains of red felspar ; more quartzose than the overlying beds ; 

 harder; more compactly and firmly cemented. On the under surface of one of the 

 beds are numerous casts of shrinkage cracks, from a mere line to an inch in width, 

 and an inch deep. In some places, there are casts of cavities in the underlying 

 rock, from six to eight inches in diameter, and an inch and a half in depth, exhi- 

 biting impressions of pebbles. The casts of the shrinkage cracks radiate in all 

 directions from the casts of the cavities or hollows just mentioned. The under sur- 

 face of this layer, together with the casts, are covered with a thin parting of bluish- 

 green clay, loaded with minute scales of mica. Calcareous. 



439. Very fine-grained shaly sandstone — colour, light red, with yellowish bands. 



440. Shaly sandstone — is more compactly cemented, and presents more of a slaty 

 appearance than Nos. 438 and 439; colour, grayish green; somewhat micaceous; 

 ferruginous on the surfaces ; calcareous. 



441. Conglomerate — made up almost entirely of rounded pebbles of quartz, of all 

 sizes, from that of a pea up to six inches in diameter, with a few fragments of chert, 

 and an occasional pebble of argillaceous slate ; the whole firmly cemented by a yel- 

 lowish siliceous paste, highly charged with oxide of iron, and containing numerous 

 grains and fragments of iron pyrites mingled with coarse sand. The cracks and 

 fissures in this rock are filled with iron pyrites. Fractures pass through the pebbles 

 without deviation. Prevailing colour, gray. 



442. Conglomerate — consisting, principally, of pebbles of quartz, cemented by 

 calcareo-siliceous matter, somewhat ferruginous, with small argillaceous white- 



