No. I.] 



GEOGNOSTICAL OBSERVATIONS. 



523 



hornblendic gneiss, which is traversed by a vein of very coarse granite 

 several yards wide. The upper part of the hill consists of strata of horn- 

 blendic gneiss, dipping N. b. W. at an angle of 45°. 



About thirty miles due north of Dog-Rib Rock, an irregular ridge of hills of 

 coarse sand and gravel occurs. The intermediate district is a continuation of 

 the gneiss formation, without any material alteration in appearance, and beds 

 of gneiss or granite occasionally shew themselves at the foot of the ridge. 

 These sand hills constitute a small height of land between the source of 

 Winter River and a dilatation of the Copper-Mine River, named Point Lake. 

 The gneiss appears in abundance on the north side of this height, associated 

 with much mica slate and some clay slate. The hills are higher here, and the 

 valleys narrower and deeper, than in the neighbourhood of Fort Enterprise. 



On an arm of Point Lake, about forty -five miles due north of Fort Enter- 

 prise, the rocks belong to the transition class. The hills here are six or 

 seven hundred feet high, and are in their general character rather round- 

 backed, but obtuse conical elevations and high and steep cliffs are very 

 numerous. 



At the encampment in lat. 65° 13' N., from whence we started on June 

 25th, the following strata occur, dipping to the westward at an angle of 80°, but 

 much waved and convoluted : — Grey wacke passing into Grey wacke slate — 

 Grey wacke with small imbedded crystals of hornblende — dark greenish or 

 blackish grey transition clay slate, having a thick slaty structure. Several 

 flat islands in the lake consist of transition green stone. A rock standing 

 apart from the neighbouring hills on the borders of the lake, about a mile and 

 a half to the southward of the encampment, having a rounded summit, but 

 bounded on three sides by mural precipices about two hundred feet high, is 

 composed of compact earthy greenstone, containing disseminated iron pyrites 

 covered with layers of transition greenstone slate. The precipices in some 

 places present a very obscure appearance of twisted columnar structure, and 

 the rock falls down in large irregular but somewhat rhomboidal fragments. 

 The upper and under surfaces of these fragments are smoothish, and present 

 a greater quantity of pyrites than is disseminated through the rest of the rock. 

 On the north side of the lake, two miles from the encampment, there is a high 

 bluff hill with a precipitous side, which seems to consist principally of a tran- 

 sition conglomerate. The basis is earthy clay slate. The imbedded masses 



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