636 WHITMAN CROSS 
CORRELATION OF FORMATIONS 
San Juan Folios, U.S. G. S. Peale ‘| Holmes Powell 
Mancos 
Cretaceous ae i 
akota or pper ’ 
Dako Upper Dakota Dakota islemoy'§ Hous 
Lower Dakota 
McElmo Dat | Flaming Gorge 
Jurassic | Gunnison Jurassic 
La Plata White Cliff 
aoe Triassic Triassic Vermilion ha 
Triassic Dolores 
Bemmean Shinarump Group 
Perminnel Cutler Permo-Carbonifer- (All assigned to 
erm e ous, or Upper Triassic) 
Carbon- Carboniferous 
iferous 
Pennsyl- Middle Upper 
vanian Hermosa Carboniferous Aubrey 
The continuity of exposures, the persistence of lithologic char- 
acters, and the simplicity of stratigraphic relations place it beyond 
question that the section under discussion has for its upper members 
the Dakota sandstone and a variable remnant of Cretaceous shales, 
everywhere of the same general characteristics. ‘The shale formation 
has been named after the town and valley of Mancos, our starting 
point, and I am aware of no reason why that name should not apply 
to the portions of that formation remaining above the Dakota, over 
the entire Plateau Province east of the Colorado and Grand Rivers, 
if not, indeed, still farther westward. 
The formation here called Dakota is that designated as ‘‘ Upper 
Dakota” on Sheets XIV and XV of the Hayden Aélas of Colorado, 
covering the portion of Colorado and Utah with which this discussion 
has to do. The “Lower Dakota” of those maps was a division 
established by Holmes for strata below the commonly recognized 
Dakota, as will shortly be explained. 
