478 Reviews — Canadian Geology. 



are several points which require elucidation in connexion with this 

 formation ; firstly, the age is very uncertain, the rocks were affected 

 by pre-Permo-Carboaiferous folding and rest on crystalline schists; 

 H. P. Woodward thought they were Devonian, but this cannot be 

 proved in the absence of fossils. Again, it is not clear whether the 

 igneous rocks of the intrusive phase followed closely on those of the 

 volcanic phase or not. Finally, the ore-bearing rocks of Western 

 Australia are all more or less associated with the NuUagine formation, 

 but it is uncertain whether the mineralization was associated with 

 the pre-Cambriau mountain-building movements which produced the 

 metamorphism in the older rocks or whether it took place after the 

 deposition of the NuDagine formation. 



W. H. W. 



YIII. — Ak Exploration of the Tazin anb Taltson Rivers, North- 

 West Territories. By Charles Camsell. Geological Survey 

 of Canada, Memoir 84. pp. iii -|- 124, with 18 plates and map. 

 Ottawa, 1916. 



IN the North- West of Canada there are still vast tracts of country 

 which are as yet unexplored; one of the largest of these 

 " blocks " forms the subject of this communication. The region is 

 situated between the Great Slave Lake and Lake Athabasca; it is 

 part of the Laurentian plateau region and abounds in lakes, while its 

 rivers flow in irregular valleys which are rarely more than 100 feet 

 deep. 



The oldest rocks, which occur now in isolated patches, are 

 " a series of schists, quartzites, conglomerates, limestones, argillites, 

 and some volcanic rocks", which are grouped together under the 

 name of the Tazin Series. These are Archaean rocks, probably 

 Huronian in age. The Tazin Series is invaded by a great composite 

 batholith of gneisses and granites with some quartz diorites. These 

 rocks, which occupy the greater part of the area, have a north and 

 south trend, corresponding more to the Cordilleran lines than to 

 those of Eastern Canada. At one place, at the north-east end of 

 Tazin Lake, there is a remnant of the Athabasca Sandstone, which 

 is a conglomeratic deposit of Keweenawan age, and probably of 

 terrestrial origin. After this rock there is a complete absence of 

 any deposit till those of the Pleistocene glaciation. The glaciation 

 in this region was very intense, as is shown by the rounded, grooved, 

 and striated character of the rocks, and by their fresh and un- 

 weathered condition. Glacial deposits, boulder-clay, moraines, 

 drumlins, and sand plains are found, but not in any great abundance, 

 the rock being mostly left bare of any surface deposit. The direction 

 of motion of the ice as shown by the strise seems to have been about 

 S. 62° W., while there is evidence of a later feebler glaciation with 

 a more northerly trend. The Tazin Series is cut by numerous quartz 

 veins which contain pyrites in places, and seem to offer some 

 prospects of valuable metalliferous deposits. The memoir contains 

 also a detailed account of the canoe routes followed by the author, 

 and is illustrated by manv excellent photographs of the country. 



W. H. W. 



