Sohuchert — Carboniferous of Grand Canyon of Arizona. 361 



some of the Supai is included with blocks of the Redwall. 

 One entire day was devoted to collecting- fossils from it, 

 but the results were very unsatisfactory. Toward the 

 middle of the Redwall were seen sections of a few corals, 

 of Menophyllum and Clisiophyllum, and a number of 

 crinoidal columnals, besides Spirifer centronatus. Of 

 the few fossils taken away, there is a Syringopora like 8. 

 surcularia Girty, Menophyllum excavatum Girty, Fenes- 

 tella and Polypora in several species, and a finely stri- 

 ate Spirifer. 



These fossils are seen to belong to the same fauna as 

 those identified by Girty 14 from near Nelson, Arizona, 

 and collected by W. T. Lee. The time indicated by them 

 is that of the Madison limestone so widely distributed in 

 the Rocky Mountain country, or of the older half of the 

 Mississippian of the Mississippi valley. 



Devono-Cambrian contact. — The Redwall usually re- 

 poses disconformably on the Muav member of the Tonto 

 formation of Cambrian age, but in many places in the 

 Grand Canyon from El Tovar Hotel west far into the 

 Shinumo quadrangle Noble has found remnants of 

 the Upper Devonian "preserved in hollows eroded in the 

 upper part of the Tonto formation." These Devonian 

 hollows are in depth up to 80 feet and were first noted by 

 Walcott in 1880. 1 ' 5 Throughout the Grand Canyon 

 area no one has found a trace of the Ordovician or 

 Silurian and none of the Lower and Middle Devonian. 

 In 1916 Noble informed the writer that in the basal con- 

 glomerates of one of these eroded hollows in Sapphire 

 Canyon he found an abundance of fish remains that have 

 been identified by Mr. J. W. Gidley as scales of Holopty- 

 chius and plates of Bothriolepis nearest to B. nitidens of 

 the Catskill formation of New York. The only hollow 

 with Upper Devonian sediments seen by the writer was 

 high above the Hermit trail on Cope Butte, where the 

 formation consists of a twisted and gnarled, mottled yel- 

 low and pink, fine-grained calcareous sandstone that 

 appears to be somewhat worm bored. It is an odd 

 deposit and probably is of fresh-water origin. The dis- 

 conformity between the Tonto and the succeeding Upper 

 Devonian or Redwall is therefore very marked and is the 

 most significant one in the Paleozoic of the Grand 

 Canyon. 



" Girty, loc. eit. 



15 C. D. Walcott, this Journal, (3), vol. 20, p. 224, 1880. 



