CAMBRIAN CORDILLERAN SECTIONS — WALCOTT I93 



ST. CHARLES FORMATION (continued) : 



3 (continued) : Feet 



Fauna (a mixture of the faunas at the base and at the top) : 



Obolus discoideus (Hall and Whitfield) [1877, p. 205]. 



Oboliis ? sp. undt. 



Lingidella maniicula (White) [1874, p. 9]. 



BillingscUa coloradoensis (Shumard) [i860, p. 627]. 



Huenella lesleyi Walcott [1908c?, p. no]. 



Hyolithcs. 



Cyrtolites. 



Agnostus. 



Ptychoparia. 



Anoinocare. 

 4. Bedded, light gray sandstone, followed below by dirty brown 

 sandstone, and toward the base shaly and thin-bedded sand- 

 stone 166 



Strike, north 20° east (magnetic) ; dip, 25° west. 

 Fauna (in upper 20 feet) : 



Obolus discoideus (Hall and Whitfield) [1877, p. 205]. 



Obolus (Fordinia) bellulus (Walcott) [1905, p. 323]. 



Acrotrcta idahocnsis aha Walcott [1902, p. 588]. 



Billingsella coloradoensis (Shumard) [i860, p. 627]. 

 Fauna (near the base) : 



Lingtilella (Lingulepis) acuminata (Conrad) [1839, p. 64]. 



Total Upper Cambrian 1,227 



MIDDLE CAMBRIAN 



NOUNAN FORMATION [Walcott, 1908a, p. 6] : 



1(7. Light-gray, arenaceous limestone 12 



lb. Lead-colored, arenaceous limestone 40 



If. Light-gray, arenaceous limestone 85 



id. Dark lead-gray, arenaceous limestone 87 



le. Shaly and thin-bedded arenaceous limestone with intercalated 



reddish brown sandy layers 15 



if. Light-gray, arenaceous limestone 18 



l^. Dark lead-gray, arenaceous limestone 198 



ih. Light-gray, arenaceous limestone 494 



li. Dark leadrgray, arenaceous limestone, with numerous irregular 



annelid borings filled with light-gray, arenaceous limestone.. 56 



ij. Massive bedded, arenaceous, cherty limestone 8 



ik. Bluish gray, cherty, more or less arenaceous limestone in thick 



bands that break up into thin layers on weathering 28 



Total of I 1,041 



Fauna: 



A few traces of fossils occur in the lower 28 feet and large 

 annelid borings occur in many of the arenaceous limestones. 

 If in a dark rock, the irregular borings are filled with 

 lighter-colored rock, and in the light-gray rock by darker 

 rock. 



