REVIEWS 411 



respectively metamorphosed silicious and argillaceous sediments. 

 Locally the base of the series is conglomeratic. They are divided into 

 an upper and a lower silicious zone. 



Torridonian strata occupy most of the unmoved area east of the fault 

 line. The beds are chiefly coarse, chocolate and red arkoses and pebbly 

 grits which carry occasional layers of shale and flagstone. 



Unconformable upon the Torridon beds lie the Cambrian. The 

 Cambrian is based with a gritty quartzite; the upper Fucoid limestones 

 carry an Olenellus fauna. 



An apparent metamorphic transition of Torridon into Moine schists 

 is reported, but no suggestion is made as to the age of the Moine schists 

 relative to the Cambrian and Torridonian. 



The petrology of the district is marked by unusual lamprophyre 

 dikes of minette and monchiquite relationships. 



The last twenty pages are given to a discussion of Pleistocene glacia- 



tion and glacial deposits. 



T. T. Q. 



The Archean Geology of Rainy Lake Re-studied. By Andrew C. 

 Lawson. Geol. Surv. Canada, Memoir No. 40, 1913. Pp. 

 115, pis. 9, map 1. 



Field study confirms the author's earlier opinion (of 1887) that the 

 Coutchiching sedimentary series is older than the Keewatin igneous 

 rocks. He found that there were two widely separated periods of plu- 

 tonic activity; to the earlier he proposes to confine the name Laurentian, 

 and for the younger he introduces the term Algoman. 



Lawson's classification of Archean formations from the top down- 

 ward is as follows: 



1. Eparchean interval — peneplanation. 



2. Algoman. Vast batholiths of granite- and syenite-gneisses. 



3. Seine series (Upper Huronian, Middle Huronian of some authors). 

 Conglomerates, quartzites and slates. 



4. Uplift, deformation and erosion, followed by depression. 



5. Steep rock series (Lower Huronian). Sediments and volcanics. 

 Several hundred feet of fossiliferous limestones. 



6. Erosion which extensively exposed the granite batholiths. 



7. Laurentian. Granites and granite-gneiss. 



8. Keewatin. Chiefly volcanic rocks with intercalated sedimentary 

 beds. Certain intrusive gabbros. 



9. Coutchiching. Sedimentary strata. Mica schist and paragneiss. 



