NO. 5 



PRE-DEVONIAN PALEOZOIC FORMATIONS 



331 



Feet 



OZARKIAN 



MoNS Formation 



I a. Hard, steel-gray and dark gray limestone in massive 

 beds above with about 50 feet (15.2 m.) of thin layers 



below^ 232 



Fauna. — In the lower portion are numerous annelid trails. 

 (65Z). 



Eoorthis sp. 



Syntrophia ? sp. 



Hyolithes sp. 



Orthothcca sp. 



Osomia lucan Walcott 



Ozarkispira Ico Walcott 



Endoceras ? robsoncnsis Walcott 



Liostegium sp. 



Keytella niarginata Ulrich MSS. 



Meters 



70.7 



Fir,. 31. — Theoretical diagrammatic section of the formations composing the 

 cliffs on the east and west sides of the lower Siffleur River canyon, just 

 before the river bends, to the west. All of the formations indicated occur in 

 the ridges of Mount Sedgwick on the west side of the Siffleur, but only the 

 Lower and Middle Cambrian were measured in the Sitifleur Canyon cliffs. 

 Fossils of the Sullivan, Lyell, and Mons formations were found in the 

 debris washed down from the higher cliffs. 



The Siffleur cliffs are illustrated by plate 85. 



An outcrop of similar limestone at the foot of the 

 cliffs on the southeast side of the canyon carries a 

 similar fauna as found in fragments of limestone 

 lying in the debris. (67k). Ocomia zone. 



lb. Gray and greenish calcareous shales, with thin-bedded 



and shaly gray limestone intercalated 498 15 1.8 



Fauna. — Immense numbers of annelid trails and small frag- 

 ments of large trilobites, none of which could be 

 identified. 



ic. Light gray, calcareo-argillaceous shale, with beds of 

 intercalated gray interformational conglomerate in 

 layers i to 12 inches (2 to 30 cm.) in thickness; also 

 considerable shaly gray limestone 528 160.9 



