Revieivs — Geological Survey of Canada. 177 



travelled over, as well as the character of the rocks and minerals 

 underlying it. 



These rocks consist of the following systems : — (I) The Laurentian, 

 which is here " applied almost exclusively to the crystalline, massive 

 or altered, crushed and contorted rocks of the Fundamental Gneiss 

 or ' Basement Complex,' consisting of granites and diorites, and 

 granite- and diorite-gneisses, which it has been impossible to separate 

 in any definite time-series." (2) The Huronian is represented by 

 the Marble Island (Hudson Bay) white quartzite, which Mr. Tyrrell 

 regards as not improbably the oldest part of the Huronian in the 

 region near the north-western shore of Hudson Bay from Marble 

 Island northward to Dawson Inlet southward. This quartzite has 

 associated with it diabase and other basic eruptives, which have 

 been intruded beneath it and have also flowed over it. (3) The 

 Cambrian rocks consist of the Athabasca sandstones and con- 

 glomerates occupying the northern part of the region explored. 

 The rock varies from a coarse conglomerate to a fine-grained, red, 

 mottled sandstone, and as no fossils were found in it the age of the 

 formation was determined on stratigraphical and lithological grounds 

 alone. Mr. Tyrrell concludes, however, that as they "hold a position 

 unconformably above the Huronian and below the Cambro-Silurian, 

 they may be assigned with probability to the Cambrian." (4) Two 

 small outliers were the only representatives of the Cambro-Silurian 

 (Ordovician) found within the area surveyed, the one being on an 

 island in Nicholson Lake, the other near Fort Churchill. Tlie fossil 

 contents of these rocks showed them to be of the age of the Trenton 

 Limestone. (5) Silurian rocks were not seen in situ, but masses of 

 white limestone scattered along the river-bank near Churchill are 

 referred to that system on the strength of their fossils, one of which, 

 a Leperditia, had been submitted to Professor T. Eupert Jones. 

 (6) The Pleistocene period is here indicated by a great glacier 

 (a map of which is given) called by Mr. Tyrrell the Keewatia 

 Glacier, the most northern of three great centres of glaciation — the 

 Cordilleran, the Keewatin, and the Labradorean, constituting a great 

 neve or • gathering-ground,' from which the ice flowed outward in. 

 all directions. 



A description of the till, moraines, eskers, ancient beaches, etc., 

 concludes the geological part of this report, to which three appendices 

 are attached, one on Chippewyan names of places, another a vocabu- 

 lary of words used by the tribe of inland Eskimos inhabiting the 

 banks of Kazan and Ferguson rivers, and the third containing a list 

 of the plants collected. 



Mr. Tyrrell's report is followed by a short one by Dr. Bell on the 

 geology of the French Eiver-sheet of the Survey Map, representing 

 the country at the northern end of Georgian Bay (Lake Huron). 

 The object of this report is to condense the information obtained, 

 from various reports by the writer and others, the coloured map 

 accompanying it (on a scale of 4 miles to 1 inch) indicating the 

 geological facts, which are therefore sparingly dealt with in the 

 text. If a vertical section could be made from the mainland along 



DECADE IT. VOL. TI. NO. IV. 12 



