JRevieics — Geological Survey of Canada. 327 



containing 1566 pages of text, and various maps and illustrations. 

 From the summary of the Director we learn that geological investi- 

 gations were carried on in all the provinces of the Dominion by no 

 fewer than twenty distinct parties, of which one was in British 

 Columbia, one in Alberta, two in Manitoba, seven in Ontario, five 

 in Quebec, one in New Brunswick, and three in Nova Scotia. In 

 the Eastern provinces the survey work consists mainly in revising 

 and adding to the details of the geology of districts which have been 

 already examined and reported on, whilst in the North-West and in 

 British Columbia the work is largely in exploring and mapping new 

 areas, and one may naturally look for greater interest and novelty in 

 the reports from these regions. 



The first report, after the summary of the Director, is by Mr. 

 E. G. McConnell on the country between the Peace Eiver and the 

 Athabasca Eiver, north of Lesser Slave Lake, comprising an area of 

 about 44,000 squai-e miles, which is for the most part a gently 

 undulating wooded plain, diversified with numerous lakes, muskegs, 

 and marshes. The lakes are *mostly shallow hollows in Boulder- 

 clay ; many of those of former times are now filled up. The greater 

 part of the region is underlain by soft dark greyish or brownish 

 shales of Cretaceous age, with but few fossils in them. They have 

 an estimated thickness of 3000 feet, and they represent the Dakota, 

 Colorado, Montana, and Laramie formations. The Cretaceous beds 

 rest directly on nodular and crumbly, nearly horizontal, limestones, 

 filled with fossils of Devonian age. Not more than 100 feet of 

 these limestones are exposed in the Peace and Athabasca regions. 

 The most striking geological feature of this district is the so-called 

 Tar-sands, exposed in the valley of the Athabasca Eiver and some 

 of its tributaries. The Tar-sands were originally unconsolidated 

 sands and soft sandstones, ranging from fine silt to coarse grit, and 

 they are now thoroughly impregnated by a bituminous material 

 which has cemented them into a coherent tarry mass. In places 

 they form high cliffs, varying from dark-brown to jet black, from 

 which streams of so-called tar issue in warm weather and form 

 pools at the base of the escarpment. The Tar-sands are exposed for 

 a distance of 90 miles along the Athabasca Valley ; they are from 

 140 to 225 feet in thickness, and have an estimated minimunr 

 distribution of 1000 square miles. The sands themselves are clearly 

 of Cretaceous age, of which they form the lowest local division, 

 and they rest directly on the greyish, crumbly, evenly stratified, 

 Devonian limestones. The enormous amount of bituminous material 

 with which the sands are now charged is considered by the Canadian 

 geologists to be the heavy constituents of petroleum oil which has 

 welled up from the underlying Devonian limestones during past 

 ages. But, strangely enough, these limestones, so far as they are 

 exposed, are by no means specially bituminous in character, and 

 the sources of the bituminous material in the sands are therefore 

 attributed to underlying beds, of which at present nothing is known. 



The Athabasca and Peace Eiver regions are so thickly covered 

 with Glacial Drift that it is only in the main drainage valleys and 



