MIDDLE CAMBRIAN FOSSILS FROM PEND OREILLE 

 LAKE, IDAHO 



By CHARLES ELMER RESSER 



Curator, Division of Stratigraphic Paleontology 

 U. S. National Museum 



(With One Plate) 

 INTRODUCTION 



From 1921 to 1924 Dr. Edward Sampson, of Princeton University, 

 then a member of the United States Geological Survey, examined the 

 Pend Oreille mining district which surrounds the southern part of 

 Pend Oreille Lake, Bonner County, Idaho. A fossiliferous Middle 

 Cambrian series crops out in several of the fault blocks into which 

 the district is divided. This was the first Cambrian outcrop discovered 

 in that part of North America. Subsequently, other Cambrian areas 

 were found in the northwestern United States and the adjacent por- 

 tions of Canada, in the extensive area previously thought barren of 

 Cambrian strata except for the occurrence in the Lewis and Clark 

 Range, west-central Montana. These occurrences were briefly dis- 

 cussed in 1934.' Since the Pend Oreille Lake area is isolated from 

 other Cambrian outcrops and the stratigraphic succession is clearly 

 determined, description of the faunas is desirable. 



Dr. Sampson published a brief summary'' of his findings in the 

 district and described the stratigraphy, naming three Cambrian 

 formations. 



BELTIAN 



Before discussing the Middle Cambrian formations a few words 

 descriptive of the underlying Beltian strata are in order. Five Beltian 

 formations, totaling more than 30,000 feet, are described beneath the 

 Middle Cambrian. This enormous thickness of sediments consists of 

 argillaceous sandstone, fine-grained massive sandstone, and hetero- 

 geneous beds of quartzite, sandstone, and argillite, with or without a 



^ Resser, C. E., Recent discoveries of Cambrian beds in the northwestern United 

 States. Smithsonian Misc. Coll., vol. 92, no. 10, 1934. 



^ Sampson, Edward, Geology and silver ore deposits of the Pend Oreille Dis- 

 trict, Idaho. Idaho Bur. Mines GeoL, Pamphlet 31 (mimeographed), 1928. 



Smithsonian Miscellaneous Collections, Vol. 97, No. 3 



