640 



C. L. DAKE 



Plicatula hydrotheca White; Camptonectes platessa White; Astarte? 

 sp.; Cardium trite White; Liopistha (Psilomya) elongata Stanton." 

 This should serve to fix the Flaming Gorge, which is next below 

 these sandstones, as at least in part McElmo, and the writer has 

 shown, in the foregoing, that it lies above a sandstone with two 



definite divisions, believed to 

 correspond to the La Plata. 



Unfortunately, at the point 

 where the fossils were collected, 

 the relations so plain in Water 

 Pocket Canyon could not be 

 seen, partly because of faulting 

 and partly because of burial by 

 lavas. However, there is but 

 little doubt in the writer's mind 

 that the Jurassic fossils were 

 found in beds below typical 

 McElmo and above the top 

 of the La Plata. He believes 

 that the McElmo formation is 

 in its upper part equivalent 

 to the Morrison, and that the 

 lower beds, apparently equiva- 

 lent to the Sundance of Wyo- 

 ming, lie above the top of the 

 true La Plata (Table I) . 



This is in marked contrast 

 to the conclusions of Emery,^ 

 who considers that the Gray 

 and Vermilion Cliff sandstones 

 are both Wingate, that the fossiliferous gypsum-bearing beds of 

 the writer's section are Todilto (middle La Plata), and that the 

 sandstones placed in the McElmo by the writer are Navajo. As 

 near as the writer can judge, Emery's chief reason for so believing 

 is the lithologic similarity of the limestones of the type Todilto 



'W. B. Emery, "The Green River Desert Section, Utah," Amer. Jour, of Sci., 

 XL VI (1918), 551-77- 



Fig. 5. — Thin-bedded red sandy shale 

 (Todilto ?) capped with La Plata (Gray 

 Cliff) sandstone, Mule Twist Canyon, 

 Water Pocket Flexure, near Henry Moun- 

 tains, Utah. 



