THE MORRISON SHALES OF SOUDHERN  COLOKAD®O 
AND NORTHERN NEW MEXICO. 
OUTLINE. 
I. Introduction. 
1. General statement. 
2. Work previously done, areas examined, etc. 
3. General structure of the region discussed. 
II. Places examined. 
1. Rio Cimarron Canyon. 
a. Detailed sections. 
6. Discussion of formations. 
c. Exeter sandstone. 
ad. Unconformity at the base of the shales. 
2. Canadian canyon. 
a. Detailed section. 
bd. Discussion of formations. 
3. Apishapa Canyon 
4. Foothills region. 
III. Summary and conclusions. 
1. The shales of the whole region form a stratigraphical unit. 
2. The shales belong to neither the Dakota nor the Red Beds. 
3. The relation of the shales to other formations. 
4. The possible connection between the Morrison and the Lower Cre- 
taceous. 
5. Correlation of the shales with the Morrison. 
Tue Morrison formation is known as the Atlantosaurus beds, 
the Como, and the non-marine Jura. It is a persistent forma- 
tion composed of colored clay-shales which contain varying 
amounts of impure sandstones and limestones. Its maximum 
thickness, so far as known, is about 400 feet, but the average 
thickness seems to be between 200 and 300 feet. It has an 
extensive distribution, but the limits are unknown. It occurs 
in the Black Hills, and has been reported from various parts of 
Wyoming. It is found over a large part of western Colorado, 
where it is known as the Gunnison, and outcrops east of the 
36 
