﻿1 6 Bulletin 20 94 



Examination of half a dozen of the canyon sections to the south 

 of Logan Canyon has shown that the Carboniferous and Devon- 

 ian portions of the section may be distinguished both by physical 

 and faunal characters. In the Devonian series, generally 1000 

 to 1200 feet thick, dark magnesian limestones are the predomi- 

 nant element, although nonmagnesian limestones and in some 

 places argillaceous rocks appear as minor components of the 

 formation. In the Carboniferous the dark magnesian lime- 

 stones of the lower series are replaced by lighter-colored non- 

 magnesian limestones. The Carboniferous and Devonian series 

 of these sections show about the same kind and degree of con- 

 trast which is found between these series in the Montana section. 

 The Devonian beds of these northern Utah sections appear with- 

 out question to be the southern continuation of the Jefferson 

 limestone. The following is a representative section occurring 

 nearly east of Paradise Post Office, in Green Canyon. 



Section in Green Canyon, Utah 



Feet. 



D. Gray nonmagnesian limestone, partly covered 900 =■= 



C. Dark-gray to black magnesian limestone, generally with 



saccharoidal texture 1 100 =*= 



B. Thin-bedded limestone, buff or brownish near top, with pe- 

 culiar concretionary development, with thin-bedded 

 bluish-gray limestone in lower part 100 



A. White to light-gray magnesian limestone, with chert or 



siliceous beds locally developed 1 50 



2250 



The dark magnesian limestone (C) seems clearly to correlate 

 with the Jefferson limestone of Montana. The following is a list 

 of species obtained from these beds in the Green Canyon section: 



Fossils from Green Canyon, Utah 

 Productella spinulicosta 

 Camarotazchia sp. 

 Spirifer argentarius 



