COMPARISON OF " SLATE CONGLOMERATES." 105 



On other occasions both Murray and Logan describe one of the slate con- 

 glomerates by saying it resembles the other; but this must be understood 

 only of the general features (see ante, p. 92 and p. 94). In his description 

 of the country around Lake Wahnapitse, Murray speaks of the lower as 

 standing nearly vertical, and having a " rough, jagged and wrinkled surface, 

 breaking into elongated splinters when struck with the hammer " {antey p. 

 92). About Lake Metagamashing the slate is " green, fine-grained and 

 finely laminated," with " rounded pebbles of syenite," and a dip of 10° to 

 12°. It is " divided by two sets of parallel joints, cutting the strata into 

 rhombohedral-shaped blocks." Sir William Logan, in his general table of 

 the constitution of the Hurouian system, already cited from the " Geology 

 of Canada," does not give a full description of the upper slate conglomerate, 

 and there is reason to think, as has been stated, that in certain regions, at 

 least, he included a portion of the lower with the upper formation. Never- 

 theless, he states that the upper has " pebbles not so large," and is " inter- 

 stratified with beds of quartzite" and "silicious slate" suitable for hones — 

 characters never attributed to the lower slate conglomerate by either Murray 

 or Logan. 



Personal Observations. — Referring again to the writer's observations on 

 the upper slate conglomerate at the outcrop two miles south of Murray's 

 hill, we find the following record published : 



" Metamorphic slates, mostly compact, with slatiness moderately well developed, 

 but to a large extent a well-characterized slaty argillite, silicious in places, and inclos- 

 ing bands of silicious schist." * 



It is impossible to possess any information respecting the Auimike series 

 without recognizing that formation here. 

 Of the formation at Murray's hill it is said: 



" It contains pebbles of red graniilite of all sizes, up to two feet in diameter." 



It recalls somewhat the peripheral portions of the Ogishke conglomerate. 



This formation is said to be " similar " to the other ; that is, they are both 

 slate conglomerates. 



The writer's brother made independently the following observations on 

 these two exposures. Of the first he says : 



"This ridge, which is a characteristic bluff of characteristic Animike slates, dips 

 S. 30° W. (magnetic). -^ * * It is minutely granular, almost aphanitic. It is 

 thin-bedded, but hardly slaty, evidently of sedimentary origin. * * ^ It breaks 

 with a flinty, subconchoidal surface of fracture." 



Of the Murray's hill formation he says : 



•' The rock is but scantily slaty in the direction of the sedimentation. Close jointage 

 sometimes produces an appearance of slatiness. Neither has it any slaty cleavage. 



* Seventeenth Ann. Rep. Minn. Geol. Survey, 1887, pp. 158, 159. 



