112 



ANNALS NEW YORK ACADEMY OF SCIENCES 



Morrison plane to be correlated with the inteiTal between the Morrison 

 and the Sundance? This question will be discussed in the section on the 

 interpretation of the Morrison formation. 



RELATION TO OVERLYING BEDS 



In western Colorado and eastern Utah the Morrison is overlain by the 

 Dakota sandstone. The contact is fairly sharp, but without definite 





Pig. 78. — Sections of the Morrison formation shotving (lecrease in thickness from 

 southwestern Colorado northward. 



A. Telluride quadrangle, Colorado ; uia-ximum thickness 900 feet ; B. Mack, Colorado, 

 thickness about 700 feet ; C. Tensleep, Wyoming, thickness about 250 feet ; D. Belt 

 Creek, Montana, thickness about 125 feet. Scale, 250 feet to 1 inch. 



evidence of erosion of the ^loirison prior to the deposition of the IDakota. 

 In Montana the Morrison is overlain b}: the Kootenie formation. The 

 Kootenie is very similar to the Morrison and may belong to the same 

 deposition cycle. In various areas in central Wyoming, from the Mon- 

 tana south to the Colorado line, the Morrison is overlain by the Cloverly 

 formation, the lower part of which is probably equivalent to the Lakota. 

 In the Black Hills area the Morrison is overlain by the Lakota sandstone. 



