RECONNAISSANCE IN COLORADO AND UTAH 635 
Paradox Valleys. The Dolores River was crossed in Paradox Valley 
and from that point the route turned again northward following the 
crest of Uncompahgre Plateau to Unaweep Canyon, the remarkable 
transverse gorge examined by Peale (29). The section exposed in 
West Creek near Dolores River was studied in some detail. From 
Unaweep Canyon we retraced our course along the Uncompahgre 
Plateau and passed down. its eastern slope to Montrose. During 
this journey, of about 450 miles, occupying 30 days, excellent oppor- 
tunities were presented for observing the stratigraphic relations of 
formations ranging from the Pennsylvania Carboniferous to the 
Mancos shale of the Cretaceous. 
It will be a great aid to the reader in comprehending the signifi- 
cance of the recorded observations if he will refer to Sheets XIV and 
XV of the Hayden Aélas of Colorado and adjacent parts of Utah, 
which represent the whole of the area traversed, with the exception 
of the vicinity of Moab. 
GENERAL CORRELATION OF FORMATIONS 
The plan of presentation will be to take up the formations of each 
system in turn and give the evidence which identifies the stratigraphic 
units adopted in the Colorado folios with certain ones found in the 
Plateau region, with suggestions, more or less definite as the case 
may be, as to correlation with the terminology of Peale, Holmes, 
and other geologists who have written upon the region visited. The 
table of correlation appearing on the following page is presented as a 
guide in following the discussion. 
CRETACEOUS FORMATIONS 
The floor of the main plain or plateau between the San Juan 
Mountains and Grand River Canyon in Utah, variously designated 
on the Hayden maps, in adjacent areas, as San Miguel Plateau, 
Dolores Plateau, and Great Sage Plain, is immediately underlain by 
the Dakota sandstone. Speaking of the very district traversed by 
our party on the outward journey, Holmes remarks that ‘over 
hundreds of square miles these sandstones lie comparatively unbroken, 
while the loose series of shales above have been swept off like so much 
dust from a great floor” (17, p. 259). 
