STRATIGRAPHIC RESULTS OF A RECONNAISSANCE 
IN WESTERN COLORADO AND EASTERN UTAH! 
WHITMAN CROSS 
One of the principal features of interest in the study of the sedi- 
mentary formations of the western mountain slopes of Colorado is 
their correlation with the formations of the Plateau Province to the 
west. I have already introduced the discussion of this subject in an 
article on the Red Beds of Colorado (8)?, but without first-hand infor- 
mation as to the Plateau country. Iam now able to review and affirm 
the correlation there suggested, on the basis of observations made 
during the summer of 1905, in the course of a reconnaissance from 
Mancos, on the southwestern flank of the San Juan Mountains, in 
Colorado, to the vicinity of Moab, on Grand River, in Utah, return- 
ing to the northern slope of the San Juan at Montrose. Other mem- 
bers of the party engaged in this reconnaissance were Messrs. L. H. 
Woolsey, W. H. Emmons, and Geo. F. Kay, all of whom had seen, 
or were to see later in the season, the stratigraphic succession of 
formations in the San Juan region. I wish to acknowledge my - 
indebtedness to all these gentlemen for observations recorded with 
my own in the following pages. 
Itinerary—The party proceeded west from Mancos to Cortez, in 
the Montezuma Valley; thence northwesterly across the headwaters 
of various branches of Montezuma Creek to the northeast base of 
the Abajo or Blue Mountains, in Utah. From this point the route 
northward lay mainly in Dry Valley which extends nearly to the 
La Sal Mountains. This part of the journey was near the line followed 
by Newberry in 1859 (28). Turning westward down Spanish Valley 
to Moab, extensive sections were examined on both sides of Grand 
River. From Moab we proceeded up the Canyon of Grand River, 
some 20 miles, and then turned east, passing over the northern slopes 
of the La Sal Mountains, and thence south through Sindbad and 
« Published by permission of the Director, U. S. Geological Survey. 
2 Numbers in parentheses refer to the bibliographic list at the end of this paper. 
634 
