MORRISON SHALES OF COLORADO AND NEW MEXICO 37 
Rocky Mountains throughout Colorado. Until recently the 
formation has not been known east of the foothills region of 
the Rockies, although it was supposed to extend for some dis- 
tance underneath the younger formations of the plains. 
During the past year, 1901, I have been interested in push- 
ing an investigation of this formation as far as possible to the 
east and south in the hope of finding its limits in these directions ; 
and in the hope also that some light might be thrown upon the © 
age of this formation, which remains a subject of some dispute. 
In a recent number of the JouRNAL oF GrEoLoey (Vol. 1X, No. 4, 
May-June, 1901) I described certain shales found in the 
canyons of southern Colorado, and gave reasons for considering 
them as the probable equivalent of the Morrison formation. 
Since the publication of that article, these shales have been 
examined by Mr. Barnum Brown, of the American Museum of 
Natural History, with a view to opening bone quarries in them. 
After an examination of several days, Mr. Brown confirmed the 
opinion that the shales are of Morrison age, and stated further- 
more that Dinosaur bones occur from a horizon fifty feet from 
the base to the top of the formation. He says ina private letter: 
I identified Morosaurus and Diflodocus vertebrz, and the lithological 
character of the beds is identical with those (Morrison) extending along the 
eastern side of the Rocky Mountains. 
My present purpose is to report progress in tracing this for- 
mation still further to the east and south, where it is exposed in 
the canyons of southern Colorado and Northern New Mexico. 
Over a large part of southeastern Colorado and northeastern 
New Mexico occurs an extensive uplift, which, roughly speak- 
ing, seems to be in the form of an oblong dome, whose axis 
lies near the Colorado-New Mexico line in the vicinity of Mesa 
de Maya. From the center, the strata dip more or less in all 
directions, unless perhaps in a southwesterly direction, where 
data are wanting. (It is possible that more detailed work will 
show that the slight southwest dip shown by Mr. Hills in his 
map of the El Mora and Spanish Peaks regions* is only local, 
U.S. Geol. Surv., El Moro and Spanish Peaks Folios. 
