184 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 53 



LOWER CAMBRIAN 



PIOCHE FORMATION: 



The Pioche formation [Walcott, 1908a, p. 11] is exposed at the westward 

 bend of Dome Canyon. P^^t 



I. Arenaceous and siHceous shaly layers, with some thicker 



layers of quartzitic sandstone 125 



Faxma : 



Annelid trails. 



Trilobite tracks (Crusiana). 



Southwest of Pioche, Nevada, on the Panaca Road, this formation contains 

 the following fauna : 



Eocystites ? longidactylus Walcott [1886, p. 94]. 



Oboliis (JVestonia) ella (Hall and Whitefield) [1877, 



p. 232]. 

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

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

 Acrothele subsidua hera Walcott [1908^, p. 87]. 

 Acrothele spurri Walcott [1908J, p. 86]. 

 Acrotreta primceva Walcott [1902, p. 593]. 

 Billingsella Jn'ghlandensis (Walcott) [1886, p. 119]. 

 . Hyolithes billingsi Walcott [1886, p. 134]. 

 Oknellus gilbcrti Meek [1874, p. 7]. 

 Zacanthoides levis (Walcott) [1886, p. 187]. 

 Crepiccphalus augusta Walcott [1886, p. 208]. 

 Crepicephaliis liliana Walcott [1886, p. 207]. 



PROSPECT MOUNTAIN FORMATION:^ 



The Prospect Mountain formation [see Walcott, 1908a, p. 12] is exposed oil' 

 the west slope and foothills of the House Range north and south of Dome 

 Canyon. Feet 



I. Gray and brownish quartzitic sandstone in layers 4 inches to 



three feet in thickness i,37S+ 



Total Lower Cambrian 1,500+ 



RfiSUMfi, HOUSE RANGE SECTION 



Upper Cambrian : Feet Feet 



Notch Peak formation 1.490 



Orr formation 1,825 



Total ■ 3,315 



* As the result of conference with Mr. Arnold Hague, the following forma- 

 tion names are given for formations in the Eureka section (see Walcott, 1884, 

 p. 284) : Eldorado limestone replaces Prospect Mountain limestone ; Dunder- 

 berg shale replaces Hamburgh shale, the name Hamburgh being retained for 

 the Hamburgh limestone. 



