208 The Ottawa Naturalist. 



Valley Toronto, is given, showing at the base, the Hudson river shale ; 

 dark or lowest till ; fossiliferous stratified sand and clay ; middle till 

 lastly, upper stratified unfossiliferous clay. 



In a former paper on the " 1 'nterglacial fossils from the Don Valley, 

 Toronto " by Dr. Coleman,* that author presents to his readers the extinct 

 faunas and floras of the various formations in that district and indicates 

 the work done by Sir Wm. Dawson, Prof. Penhallow, Dr. W. H. Dall 

 and Mr. C. T. Simpson, the last two, of the Smithsonian Institution, 

 Washington. This paper and the one under present consideration are 

 important contributions to a most interesting section of cenozoic 

 geology. 



Adams, Frank D. " A further contribution to our knozvled^e of the 

 Laurentian;" American Journal of Science, Vol, L. Art. VII, 

 pp. 58 69, with plates 1 and 2, New Haven, July 1895. 



This timely article by the well known professor of Geology ot McGill 

 University brings forward a summary of results obtained from observation 

 and study both in the field and in the laboratory of the Archaean rocks ex- 

 posed in the region to the north of the city of Montreal. The information 

 was chiefly obtained while acting as field geologist on the Geological 

 Survey of Canada, the facts and deductions acquiring additional weight 

 from the author's well known ripe petrographical knowledge and a 

 varied experience with the various problems connected with the com- 

 position and genesis of Archaean rocks. 



This paper opens with a general description of the delimitation of 

 the two great subdivisions of the Archaean Laurentian and Huronian 

 as developed in the Dominion of Canada. The origin and composition 

 of the gneisses constituting the Laurentian are the chief points considerd 

 and the various facts relating thereto obtained by a careful examination 

 in the field as well as a critical microscopic study of one hundred and 

 sixty typical specimens representing as far as possible all varieties of the 

 rocks occurring in the district. The region in question lies to the east 

 of that examined by Logan and later by Ells and comprises an area 

 composed of 3500 square miles underlain by the crystalline rocks of 



* American Geologist, Vol. XIII, pp. 8595, Feb. 1894. 



