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CANADA. 



335 



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Lake Superior, while the above greenish slates (No. 3) were not sepa- 

 rated from the preceding rocks (Nos. 1 and 2) until many years later. 

 (See Am. Jour. ScL, 1852, (2 ) XIY. 224-229 ; 1857, XXIIL 305-314; 

 Azoic Rocks, pp. 71, 72, SO.) 



In the Keport of Progress for 1847-48, Mr. Murray gives some ac- 

 count of the sequence of the rocks on the islands and northern shore of 

 Lalvo Huron. 



*' Tlio older groups observed consist, firstly, of a metarnorpliic scrioR, com- 

 posed of granitic and syenitic rocks, iu the forms of gneiss, mica slate, and 

 horublendo slate ; and, secomlly, of a straiiried series composed of (]_uartz rock 

 or sandstones, conglomerates, shales and limestones, with hiterposed beds of 

 greenstone ; " 



succeeded by fossilifcrous formations, i. c. Potsdam sandstone, etc. 

 Certain of the conglomerates of the second series arc said to contain 

 pebbles and boidders of syenite, but beyond this nothing is advanced to 

 show the relations of this to the granitic and syenitic rocks, the two 

 scries not being seen in contact. The relation of ihc fossilifcrous forma- 

 tions to the preceding series was shown clearly enough, the separation 

 being a marked one. (/. c, pp. 107—113.) 



Mr. Murray further says : 



*'0n a cluster of small islands .... Granite, [lithologically like the 



Laurcntian,] was found breaking through the (p.iart/-rock The colour 



of ilie rock was red. On one of the islands, qnartz-rock beds on opposite 

 sides of the granite were observed Lo dip in opposite directions, north on the 

 north side and south on the south side, at an angle of 70° or 80° ; and in an- 

 other of the islands the cpiartz-rock and gi'anile were seen in juxtaposition, the 

 former reclining on the latter. In liiis case the (ptartz rock was traversed by 

 several trap dykes running sli-iilly obhcpie to the strike, while granitic veins 

 ran transversely tlirough the wlii*le, and were continued throu^-h a main bmly 

 or unclcus (if granite, the one gvaiute being distinguishable from the other, 

 notwithstanding the red color of both, by the fmer texture of the veins." {I. c, 

 pp. 112, 113.) 



In a "Report on the North Shore of Lake Huron," under date of 

 December 20, 1848, Mr. Logan gives some account of the second series 

 described by Mr. Murray, and states : 



"Tlie series of rocks occupying this country from the connecting link be- 

 tween Lakes Huron and Superior to the vicinity of Bhebawenahning, a distance 

 of ]20 miles, with a breadth in some places of ten, and in others exct-ediug 

 twenty milesj it appears to me, must be taken as belonging to one forma- 



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