646 EDWARD STEIDTMANN 



The Whiskey Lake'' area includes two unsubdivided townships, 

 Nos. 137 and 138, in the third and fourth tier of townships north 

 of Lake Huron. The pre-Cambrian rocks of the area are provi- 

 sionally classified as: 

 Middle Huronian — Conglomerate and quartzite 



Unconformity 

 Lower Huronian — Conglomerate, quartzite, slate, and limestone 



Great unconformity 

 Sudbury series — Slate and probably quartzite, part of the greenstone 



Unconformity 

 Keewatin — Most of the greenstone and green schist 

 Laurentian — Granite and syenite 



Coleman^ classifies the pre-Cambrian succession along the north 



shore of Lake Huron as follows : 



Keweenawan — Basic volcanic eruptives and basic sills. Subordinate coarse, 

 usually red sediments, probably indicating warm, dry climate 

 Animikie — Black slates, volcanic tuff, bowlder conglomerate 

 Huronian — Arkose and quartzite, shallow lake or sea deposits indicating cool 

 climate. Bowlder conglomerate or tillite formed under glacial 

 conditions 

 Sudburian — Pillow basic lava flows. Coarse sediments — conglomerates, 

 bowlder beds, arkoses, quartzites derived mainly from the dis- 

 integration of granites 

 Grenville — Quartzites, schist, and impure calcareous sediments whose relation 



to the Keewatin is uncertain. Intrusion of granites 

 Keewatin — Basic eruptions and jaspititic iron formations 



Coleman^ classifies the pre-Cambrian rocks of the region north 

 of Lake Huron extending from Point Mamainse to Wanapitie as 



follows : 



Keweenawan 

 Discordance 

 Post-Laurentian < Animikie 



Discordance 

 Upper Huronian 



Great discordance 

 f Sudbury series 

 Pre-Laurentian < Great discordance 



[ Keewatin — Probably equal to the Grenville series 



' A. P. Coleman, "The Whiskey Lake Area," Ontario Bur. Mines, 22d Ann. Rept., 

 Vol. XXII (1913), Part I, pp. 146-54, 5 figs. 



^A. P. Coleman, "The Pre-Cambrian Rocks North of Lake Huron with Special' 

 Reference to the Sudbury Series," Ontario Bur. Mines, Ann. Rept., Vol. XXIII (1914), 

 Part I, pp. 204-36, map, 18 figs. 



3 A. P. Coleman, "The Sudbury Series and Its Bearing on Pre-Cambrian Classi- 

 fication," Congres Geologique International XII. Session 1914. 



