1872.] 



NICHOLSON NORTH SHORE OF LAKE SUPERIOR. 



21 



Leaving Prince Arthur's Landing by the 

 Dawson Road, we pass for the first three or 

 four miles over the black shales and interstra- 

 tified traps of the " Lower Copper-bearing 

 series." Four or five miles to the north- 

 east of Thunder Bay there comes on a range 

 of syenitic and gneissic rocks of Laurentian 

 age, as I should imagine by the interven- 

 tions of an E. and W. dislocation ; and these 

 continue to be exposed for several miles. 

 These in turn are succeeded to the N.W. by 

 a vast series of rocks referable to the Huro- 

 nian Group(see Map, fig.1 , and section, fig. 2). 

 The first members of this series consist of 

 greenish or grey slates, with bands of gneiss 

 and occasional trap-dykes. At the Govern^ 

 ment post known as the " Fifteen-mile 

 Shanty," and from here up to the foot of Lake 

 Shabendowan , a distance of 32 miles, we cross 

 a succession of bedded traps, mostly green in 

 colour, interstratified with great masses of 

 greenish, grey, or drab-coloured slate. The 

 road runs a little to the north of west, and 

 the general strike of the beds is W. by IS . 

 and E. by S. ; so that the actual thickness 

 of beds crossed over, though very consider- 

 able, is not so great as might at first sight 

 appear to be the case. These Huronian 

 slates and traps present a most singular 

 resemblance to the green slates and por- 

 phyries of the Lake -district of the north 

 of England. This likeness is shown in their 

 mode of weathering, in the kind of scenery 

 produced, and especially in the lithological 

 character of the slates. The slates in ques- 

 tion have a prevailing green colour, are 

 usually fine-grained, but are not unfre- 

 quently brecciated, and are divided by a 

 more or less nearly vertical cleavage, the 

 direction of which is remarkably persistent 

 over very large areas. The surfaces of the 

 slate are not uncommonly glossy ; and in 

 some cases, at any rate, tbe cleavage ap- 

 pears to coincide with the bedding of the 

 rock. These slates have been generally 

 spoken of as " talcose" or "chloritic" slates ; 

 but I entertain no doubt that they are truly 

 of the nature of bedded felspathic ashes. 

 They do sometimes contain talc, and are 

 occasionally serpentinous ; but I am satisfied 



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