h™ ^J 





■J-- *- - 7 



\. 



EKSUME, AND GENERAL DISCUSSION. 



523 



Azoic of Foster and Whitney. These rocks had been met with by tlie 

 geologists of the Canada Geological Survey, and were designated by 

 them in the Ptcport of Progress for 1845-40 as the '^ Mctamorphio 

 Scries," * their geological position not having been clearly ascertained, 

 nor the question considered whether the lowest Lower Silurian really 

 formed the base of the fossiliferous strata, so that rocks underlying 

 them unconformably could properly be called Azoic. 



After the publication of Foster and Whitney's Eeport — in 1854, 

 namely — Mr. Logan, the chief of tiio Canada Survey, recognizing the 

 fact that the term *'metamorphic " had no special significsiuco as desig- 

 nating the geological age of any group, since rocks in any part of the 

 series may be metamorphic, adopted for the Azoic of Foster and Whit- 

 ney the designation of " Laurentian," a name previonsly proposed by 

 an eminent authority for a group at the other end of tlie geological 

 series, and already in current use — an' act of great injustice, as wo 

 have already pointed out.f Neither was any reference made in the 

 report of the Canada Survey, in which the name " metamorphic " was 

 exchanged for that of " Laurentian,*' to the fact that the geological 

 position of those rocks had previously been definitely established, and 

 another name given to them by the American geologists working on 

 the southern side of Lake Superior. 



Furthermore, owing to the inability of Mr. Logan to distinguish be- 

 tween the Azoic quartzites of Lake Huron, and the very dissimilar 

 sandstones, conglomerates, and interbedded volcanic rocks of Keweenaw 

 Point, utter confusion was introduced into the geology of the region of 

 the Upper Great Lakes — in the minds, at least, of those accepting the 

 dicta of the Canada Survey as authority — a condition of things which 

 was not fully rectified until many years later, t 



For some time after the introduction of the term " Azoic " into the 

 geohtgical nomenclature by Foster and Whitney, that term Avas current 

 among geologists in this country. Dana, in the first edition of his 

 '* Manual of Geology," the Preface of wliich bears the date of Novem- 

 ber 1, 18G2, and in the revised edition, issued in 1871, in which it is 

 stated that the work " bus received such alterations as seemed to bo 



ill 



* Sec aiUey pp. 331 ct seq. 



i- Sec ante, pp. 7, 338. Also, Am. Jour. Sci., (2), XXIII. 305-314 ; Proc. Bost. 

 Soc. Nat. Hist, XXI. 121, 122. 



t Soc a stiilciiieiit in refercnt^e to the results attained by the Geological Survey of 

 Canada, published hy A. U. C. Selwyn, present chief oC that Survey, in ''Science," 

 number of February 9, 1883. 



