NO. 5 PRE-DEVONIAN PALEOZOIC FORMATIONS 3II 



Feet Meters 



Arctomys Formation 



I. Variable arenaceous shales with alternating bands of 

 color — greenish, deep red, buff, yellow and gray. 



Numerous mud cracks and ripple-marks occur on 

 many of the layers, and a few casts of salt crystals on 

 some of the buff-colored arenaceous shaly layers.... 268 81.7 



Total Arctomys formation 268 81.7 



MIDDLE CAMBRIAN 

 Eldon Formation 



la. Irregularly-bedded, gray siliceous and arenaceous lime- 

 stone in thick layers above and thin layers below ; at 

 192 feet (58.5 m.) from the base, a bed of bluish- 

 black limestone is fossiliferous. Above the fossilif- 

 erous bed, the strata become more massive, arena- 

 ceous, steel-gray in color, weathering to light gray.. 410 125.0 

 Fauna. — (57x) : 192 feet (58.5 m.) above the base. 

 Agnostus sp. 

 " Ptychoparia" 2 species 

 Bathyiiriscus-\\kt pygidium 

 \h. Light and dark gray, thin-bedded arenaceous limestone, 



weathering to a light gray color no 33.5 



ic. Massive-bedded, siliceous, fine-grained, compact, dark 



bluish-gray limestone 197 60.1 



Two yellowish-buff-weathering bands of limestone 

 2 to 3 feet (.6 to .9 m.) thick stand out in color on 

 the face of cliffs. 

 Fauna. — (57w) : near the summit. 



Billingsella ? sp. 

 Neolenus-\\]<.t pygidium 

 \d. Massive-bedded limestone much like that of ic 71 21.6 



Total of 1 788 240.2 



2. Thin-bedded, bluish-gray limestone, with irregular 



layers and stringers of gray, buff-weathering, dolomi- 



tic limestone 95 29.0 



At 24 feet (7.3 ni.) from the base a shaly, bluish- 

 gray, siliceous limestone about 2 feet (.6 m.) thick is 

 interbedded. 

 Fauna. — (in shaly limestone) : 



Oboliis mcconnelli Walcott 



Obolus membranaceous Walcott 



Lmgulella sp. 



Iso.rys cf. argent ea (Walcott) 



Elrathia sp. 



3. Massive-bedded, dark gray, arenaceous limestone.... 190 57.9 



4. Massive-bedded, cliff-forming, light gray arenaceous 



limestone. At several horizons occur bands of thinner 



