202 D. D. CAIRNES ^SECTION ALONG YUKOX-ALASKA BOUXDARY 



Fossils are of rather rare occurrence in all but the limestone members 

 of this group, which are highly fossiliferous. Fossil remains were, how- 

 ever, collected from the shale, sandstone, and quartzite beds at a number 

 of widely separated points. All the Mesozoic remains that were obtained 

 have been examined by Dr. T. W. Stanton, of the United 'States Geologi- 

 cal Survey, who considers most of them to be characteristic of the Lower 

 Cretaceous. Concerning one rather large but imperfect lot, he is, how- 

 ever, able to state only that "my judgment is that these fossils are not 

 older than Mesozoic and that they may be Cretaceous." The Orange 

 group is thus considered as being dominantly Mesozoic, but includes as 

 well certain Upper Carboniferous argillaceous, arenaceous, and calcareous 

 members which contain fossils that are of Permian or Upper Pennsyl- 

 vanian age. These beds overlie the members of the Eacquet group, in 

 which Mississippian and Pennsylvanian fossils occur. 



The Mesozoic members of the Orange group of sediments correspond 

 somewhat closely lithologically and stratigraphically with those of the 

 Laberge series,*^ which extensively developed in Yukon*" and northern 

 British Columbia, and particular}' resemble these beds in Atlin district,** 

 British Columbia, where they are locally much metamorphosed and altered 

 into slates, quartzites, and related rock types. The members of the La- 

 berge series are considered to be mainly at least of Lower Cretaceous or 

 Jurassic age and classed provisionally as Jura-Cretaceous. On account 

 of the distinctive appearance of certain of the members of the Orange 

 group, especially the banded red and green slates, these are thought in 

 all probability- to correspond stratigraphically with certain beds occurring 

 on the MacMillan and Upper Stewart rivers, which have been described 

 by both Mr. R. G. McConnell*^ and Mr. Joseph Keele,^^ of the Canadian 

 Geological Survey. Mr. Keele found Tria-ssic fossils in or immediately 

 below these rocks, which appear to correspond to the members of the 

 Orange group. 



Quaternary — Superficial deposits. — ^Under "Superficial deposits'^ the 

 writer means to include all the Pleistocene and Recent sedimentary de- 



*« D. D. Cairnes : Preliminary memoir on the Lewes and Nordensklold Rivers coal dis- 

 trict Yukon Territory. Geol. Surr. of Canada. Memoir No. 5, 1910, pp. 30-35. 



*'' D. D, Caimes : Wheaton district, Yukon Territory. Geol. Surv. of Canada, Memoir 

 No. 31. 1912. pp. 53-57. 



** D. D. Cairnes : Portions of Atlin district, British Columbia, with special reference 

 to lode mining. G^ol. Surv. of Canada. Memoir No. 37. 1912, pp. 59-63. 



<* R. G. McConnell : The MacMillan River, Yukon district. Geol. Surv. of Canada, 

 Ann. Rept, vol. xv. 1902-1903, pp. 31A-34. 



«* Joseph Keele : The Upper Stewart River region. Yukon. Geol. Surv. of Canada, vol. 

 XTl, 1904, pp. 13C-18C. 



A reconnaissance across the Mackenzie Mountains on the Pelly, Ross, and Gravel 

 rivers. Yukon and Northwest territories. Geol. Surv. of Canada, No. 1097, 1910. pp. 33- 

 36, 39-40. 



