On the Norian or "Upper Zaurentian" Formation. 427 



(/) On the East Coast of the Georgian Bay, 

 on Lake Huron. 



Bigsby 1 described, long ago, an occurrence of anorthosite 

 on the north-east coast of Lake Huron, which, according 

 to him, has a breadth of five miles. He also mentions 

 that the rock is well exposed and has a massive character, 

 but gradually merges into gneiss. The feldspar is greenish- 

 blue and grey in colour ; it forms crystals of an average 

 diameter of about one inch, and sometimes much larger. 

 Unfortunately, the locality is not indicated exactly, but 

 according to his description it must be in the neighbour- 

 hood of Parry Sound, and I have therefore on the map 

 indicated the occurrence in that vicinity. According to 

 Bell, 2 Long Inlet", ten and a half miles long and situated 

 farther south on the same coast, is likewise cut in a band 

 of white granular plagioclase, mixed with a little quartz 

 and black mica. 



(g) Elsewhere in Canada. 

 The occurrences of anorthosite above described are the 

 only large and important ones that are known. Elsewhere 

 in the Laurentian, small bands and bosses of the rock are 

 found, but they are too small and unimportant to deserve 

 further mention. They occur, for the most part, in the 

 neighbourhood of the masses above described. Other 

 occurrences have been referred to this group of rocks, 

 but it is not known as yet whether they really belong 

 to it. Vennor, for example, mentions one in the Lauren- 

 tian, north of the east end of Lake Ontario. There is 

 also an occurrence in the vicinity of Dolin's Lake, near 

 the City of St. John, New Brunswick. An examination 

 of a specimen from- the last mentioned locality shows it 

 to be an olivine-gabbro. 3 



1 Bigsby, A List of Minerals and Organic Remains occurring in the Canadas.— Am. 

 Jour, of Sc, 8, 1824. 



2 Bell, Rep. of the Geological Survey of Canada, 1876-77, p. 198, 



3 Note.— See also a paper by Dr. A. C. Lawson, which has appeared since the pub- 

 lication of the present paper, entitled " The Anorthosytes of the Minnesota Coast of 

 Lake Superior."— Geol. and Nat. Hist. Surv. of Minn. Bull. No. 8, 1893. 



