CANADA. 330 



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. Sci., 1852, (2 ) XIV. 224-229 ; 1857, XXIII. 305-314; 

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



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

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

 Lake Huron. 



" The older groups observed consist, firstly, of a metamori)liic series, com- 

 posed of granitic and syeiiitic rocks, in the forms of gneiss, uuca slate, and 

 hornblende slate ; and, secondly, of a stratified series composed of quartz rock 

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

 greenstone ; " 



succeeded by fossiliferous formations, i. e. Potsdam sandstone, etc. 

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

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

 show the relations of this to the gi-anitic and syenitic rocks, the two 

 series not being seen in contact. The relation of the fossiliferous forma- 

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

 being a marked one. {l. c, pp. 107—113.) 



Mr. Murray further says : — 



"On a cluster of small islands .... Granite, [lithologically like the 



Laurentian,] was found breaking through the quartz-rock The colour 



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

 sides of the granite were observed to 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 quartz-rock and granite were seen in juxtaposition, the 

 former reclining on the latter. In this case the quartz rock was traversed by 

 several trap dykes running slightly oblique to the strike, wdiile granitic veins 

 ran transverselj^ through the whole, and were continued through a main body 

 or nucleus of granite, the one granite being distinguishable from the other, 

 notwithstanding the red color of both, by the finer texture of the veins." (1. c, 

 pp. 112, 113.) 



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

 December 29, 1848, Mr. Logan gives some account of the second series 

 described by Mr. Murray, and states : — 



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

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

 of 120 miles, with a breadth in some places of ten, and in others exceeding 

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



