REVIEWS 177 



slate, and ferruginous dolomite slate — in fact, all possible graduations and mixtures 

 of the minerals dolomite, hematite, quartz, and such argillaceous minerals as kaolin 

 and chlorite. In the ferruginous rocks associated with the iron ore the iron occurs as 

 hematite and also in the form of carbonate, isomorphous with carbonate of calcium, 

 magnesium, and manganese in the form of ferro-dolomite and manganic-ferro-dolomite, 

 and as silicates combined with various proportions of alumina, lime, magnesia, and 

 manganese, as chlorite and mica, and also very probably to a small extent as iron 

 phosphate. 



It is believed that the iron ore of the Baraboo district was originally a deposit of 

 ferric hydrate, or limonite, formed in comparatively stagnant, shallow water, under 

 conditions similar to those existing where bog or lake ores are being formed today, 

 and that through subsequent changes, long after the iron was deposited as limon- 

 ite, while the formation was deeply buried below the surface and subjected to heat 

 and pressure, the original limonite became to a large extent dehydrated and changed 

 to hematite. 



Comment. — The theory of the origin of the ores here proposed differs from that 

 worked out for the Lake Superior region. It is believed that insufficient data are yet 

 at hand to warrant a positive statement concerning the origin of the ores, and that until 

 such data are at hand the theory worked out for the Lake Superior region in general, 

 with which the Baraboo district has many points in common, should be assumed to 

 apply to the Baraboo district. A detailed analysis and criticism of Dr. Weidman's 

 argument is published by the reviewer in Vol. XXXV of the Transactions of the Ameri- 

 can Institute of Mining Engineers. 



Drilling in the east-central portion of the valley has recently seemed to show the 

 presence of an Upper Huronian quartzite series unconformably overlying the series 

 described by Weidman, but this is yet to be confirmed. 



James M. Bell. "Economic Resources of Moose River Basin." Report of the 

 Ontario Bureau of Mines, Part I (1904), pp. 135-97. 



Bell describes the Laurentian and Huronian rocks of the Moose River basin. 

 The former include acid igneous rocks, and the latter, greenstones, green schists, and 

 certain sediments, with doubtful relations to each other and to the Laurentian. 



George F. Kay. "The Abitibi Region." Report of the Ontario Bureau of Mines, 

 Part I (1904), pp. 104-34. 



Kay describes the rocks seen on a trip from Mattagami to Nighthawk and the 

 area west of Lake Abitibi. No attempt is made to describe their stratigraphy and 

 structure. 



A. P. Coleman. "The Classification of the Archean." Proceedings and Trans- 

 actions of the Royal Society of Canada, Vol. VIII (2d Ser., 1902), Sec. IV, pp. 

 135-48. 

 Coleman discusses the classification of the Archean (pre-Cambrian of the U. S. 



Geological Survey), and proposes the following: 



Middle and f Keweenawan 



Lower Cambrian ? { (Unconformity) 

 or Algonkian ? [ Animikie 



