570 Cant DANG: 
of shales and sandstones. No fossils were noted in this vicinity, 
but near Teasdale, in Wayne County, the writer found abundant 
marine fossils, chiefly pentagonal crinoid stems in a thin limestone, 
a few feet above the contact of this formation with the underlying 
massive sandstones. Fossils were also found at the same horizon 
near Loa. The McElmo beds are highly variegated, red, pink, 
gray, green, and maroon being common shades. Gypsum, in beds 
up to roo feet or more thick, occurs in the lower half of the forma- 
tion. About 400 feet below the top of the McElmo occurs the 
Salt Wash member, a very conglomeratic gray coarse sandstone. 
The McElmo has a highly characteristic bad-land topography. 
Following the McElmo occurs the Dakota formation of Cretaceous 
age, usually 25 or 30 feet thick, a coarse gray sandstone, at places 
highly conglomeratic and outcropping in hogbacks. Above the 
Dakota is the Mancos, a bluish-gray soft shale 2,000 to 3,000 feet 
thick, forming broad plains. 
STRUCTURE 
Lupton,’ on his map of the Green River field, does not show the 
formations in the area involved in this description, but he writes 
the word “‘anticline”’ along the axis of the structure in question, 
leaving the area blank, since it was outside the field involved in his 
report. As seen from the west, along the Green River-Moab road 
or the Thompsons-Moab road (Fig. 1), the structure appears to be a 
simple anticline, the limbs of which rise gradually from the adjacent 
plain of Mancos shale to the northeast and southwest. Two scarps 
about a mile apart face each other from these limbs and overlook 
a central or axial valley which strikes about N. 45° W. At first this 
was supposed to be a simple anticlinal valley, but the extreme 
straightness of these scarps for several miles aroused suspicion, so a 
careful examination of the structure was made. It was found to be 
a well-developed anticline, along the crest of which occurs a typical 
graben or down-faulted trough about a mile wide (Fig. 2.). The 
relationships are clearly brought out in Figs. 3 and 4. Outcrops of 
Mancos shale were found almost in contact with La Plata sandstone. 
This would give the fault a displacement of perhaps 1,200 feet or 
1 Loc. cit. 
