OF THE ROOKS OF L A K E S U P E R I 0 R. 



259 



lumps ; and it is probably analogous in its formation to the basaltic grits, its rela- 

 tions being with the Anorthite and Palisade rocks, and its date cotemporaneous with 

 the eruption of that rock. 



623. Bears, apparently, E. of N. This rock is very ferruginous, very crystalline 

 in its aspect, and exhibits decided polarity. In its structure it has a somewhat 

 schistose appearance, especially on exposed surfaces, and is most likely an overflow 

 from a N. 30° E. dike of basalt. Colour, blackish gray, with a shining appearance. 

 It is the same as No. 613, which resembles " Nepheline rock," and which bears E. 

 and W. The difference in bearing is easily accounted for, if it is a bedded rock, as 

 it seems to be. Between the regular layers it is coated with oxide of iron, which 

 gives that portion of the rock a thoroughly rusty appearance. It contains a great 

 quantity of iron, and it is probable that it is from rock of this character that the 

 ferruginous beds associated with the conglomerates have been derived. (See No. 

 603.) 



624. Bears N. 45° W. Colour, purplish gray; fine granular; jointed. Com- 

 posed of red felspar and black hornblende or augite. Resembles No. 618, but has 

 more of a bluish tint. Magnetic. Smooth, conchoidal fracture. Bears most analogy 

 to the N. and S. dikes. Weathered surfaces, black and smooth. Joints slightly 

 incrusted with a zoolitic mineral, probably Heulandite. It is very compact, and 

 shows no appearance of crystallization. Traverses No. 603 and No. 625. 



625. Bears N. 30° E. Resembles No. 603, and is probably a dolerite. Colour, 

 dark greenish gray. Minutely crystalline, with occasional larger crystals of a 

 greenish felspar (?) disseminated through it. Irregular fracture. Is more nearly 

 like No. 615. Weathered surface black, somewhat irregular, but tolerably smooth. 

 The joints contain thin incrustations of carbonate of lime. Magnetic. Minute 

 scales of mica disseminated through it. Is traversed by No. 624. It may be com- 

 pared with No. 613, but is less crystalline than this last-named rock. Belongs to 

 the basaltic series ; contains a great deal of deep olive-green mineral, soft, and 

 having a lighter green streak. 



626. This specimen, which is from the bed of conglomerate which lies between 

 the Palisade rock and No. 624, is a baked clay. It is of a rather light brick-red 

 colour, shows traces of lines of deposition, and is somewhat amygdaloidal, the cells 

 being very irregular in form, and compressed, with minute crystals of minerals, 

 probably zeolitic, incrusting their sides. Has been much broken up and contorted 

 by the intrusion of No. 624. Belongs to the lower shale-beds of the creek behind 

 the Palisades. In some places the clay is discoloured, being dirty white or yellow, 

 and in such instances is harder than the other parts of the rock. 



627. Metamorphosed slate, from the same breccia as No. 626. Very fine-grained. 

 Colour, bluish gray — not unlike the altered slate at the Lower Falls of Pigeon 

 River. (See Nos. 4 and 8.) In the joints of these fragments are incrustations of a 

 green mineral, supposed to be epidote. The slate is amygdaloidal, the cavities being 

 filled with calcareous spar, surrounded, in many cases, by a ring of chalcedony. Frac- 

 ture irregular and jagged, and, in some directions, splintery. A ring of zeolite, in 

 some of the cells, surrounding a nucleus of calcareous spar. 



628. Brecciated conglomerate — some of the fragments large, and of a deeper red 



