CAMBRIAN CORDILLERAN SECTIONS — WALCOTT 183 



HOWELL FORMATION (continued): 



Feet 



xe. Gray, siliceous limestone in layers 2 to 10 inches thick 70 



if. Bluish black limestone in massive layers, breaking up into thin 



layers on weathering 102 



Fauna: 

 Ptychoparia. 

 Bathyuriscus. 



ig. Gray, siliceous limestone in thick beds 90 



Total of Howell formation 435 



S pence shale: 



The Spence shale [Walcott, 1908a, p. 8] is exposed on the east side of Dome 



Canyon a little above where it bends to the westward. Peet 



I. Pinkish, argillaceous shale 20 



Fauna : 

 Micromitra (Iphidella) pannula (White) [1874, p. 6]. 

 Oholus (Westonia) ella (Hall and Whitfield) [1877, P- 22,2\. 

 Lingtilella dubia (Walcott) [1898, p. 401]. 

 Acrothele subsidiia (White) [1874, p. 6]. 

 Hyolithes billingsi Walcott [1886, p. 134]. 

 Ptychoparia piochensis Walcott [1886, p. 201]. 

 Ptychoparia sp. 



Zacanthoides typicalis (Walcott) [1886, p. 183]. 

 Bathyuriscus productus (Hall and Whitfield) [1877, p. 244]. 



LANGSTON (?) FORMATION: 



The section of the beds which are doubtfully placed in the Langston forma- 

 tion [Walcott, 19080, p. 8] was measured at the same locality as the Spence 

 shale. Feet 



la. Massive bedded, bluish gray, arenaceous limestone, with irregu- 

 lar partings of buflf-colored arenaceous limestone. The latter 

 penetrates the layers of limestone in the most irregular 

 manner and frequently surrounds small, irregular nodules 

 of the bluish gray limestone 170 



Fauna: 



Billingsella, sp. undt. 



Platyceras. 



Hyolithes. 



Leperditia. 



Ptychoparia. 



Zacanthoides. 



Dorypyge? 



lb. Brovyn, buflF weathering, arenaceous limestone in thick layers; 



almost sandstone in places 35 



Total of Langston (?) formation 205 



Total Middle Cambrian 4,417 



