2l6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 75 



HcberteJla occidentalis (Hall) 

 Dinorthls subquadrata (Hall) 

 Maclurina sp. 

 Endoccras sp. 



Dr. Kirk, in submitting the report on the fossils, wrote : * 

 The Beaverfoot (Richmond) is composed in the main of heavy bedded 

 dolomitic limestones, weathering brownish to lead colored. It seems to vary 

 in thickness in different sections. In the Upper Columbia Lake and Windermere 

 Creek sections it apparently does not exceed 200 feet in thickness. In the 

 Sinclair Canyon sections higher beds are present, consisting of thinner-bedded, 

 purer limestones, and here it attains a thickness of about 400 feet. The fauna 

 is identical with that of the upper Bighorn of Wyoming, of the upper portion of 

 the Fremont of Caiion City, Colorado, and of the Richmond of Stony Mountain, 

 Manitoba. 



Mrs. Walcott and I collected, from the lower 20 feet (6.1 m.) of the 

 limestone above the Wonah quartzite in Sinclair Canyon, the follow- 

 ing as identified by Dr. Kirk : 



Columnaria alveolata Goldfuss 



Columnaria {Palcophyllnm) d.stokcsi (Edwards and Haime) 



Favosites sp. 



Streptelasma rusticitin Billings 



Rhynchotrema argenturbica (White) 



Zygospira cf. recurvirostris Hall 



Plectambonites cf. saxcus (Sardeson) 



Hebertclla cf. occidentalis (Hall) 



Dinorthis cf. subquadrata (Hall) 



The known Richmond fauna has such a wide distribution in the 

 Mississippi drainage area, the Cordilleran region, and Alaska, and 

 it is so distinctive, that its value as a horizon marker is unquestioned, 

 and it is especially valuable in the Beaverfoot-Brisco-Stanford Range 

 area as it occurs above a strongly marked disconformity between 

 the Ordovician and Silurian. It characterizes the Beaverfoot forma- 

 tion so clearly that it is not possible to unite the Beaverfoot with the 

 Brisco formation, which has a very different fauna. A superficial 

 knowledge of the faunas of the Beaverfoot and the Brisco might 

 lead to erroneous identification, and cause the unwary geologist to 

 attempt to establish transitional faunas and to include two formations 

 in one, but a thorough study and comparison of all the elements 

 entering into the problem — lithologic, stratigraphic, and faunal — will 

 usually lead to the discovery of unsuspected evidence of discon- 

 formity and faunal changes of such magnitude as to warrant the 

 demarcation of distinct formations in an apparently continuous strati - 

 graphic and faunal series of strata. This has occurred many times 

 in the past and will occur in the future. 



' Smithsonian Misc. Coll., Vol, 75, No. i, 1924, p. 13. 



