248 C. SCHUCHERT MORRISON AND TENDAGURU FORMATIONS 



Dr. S. S. BiTclonan, of England. It appears, however, to be the obvious 

 correlation to make and if done seems to explain better the close sim- 

 ilarit}' of the sanrians in the two upper dinosaur zones. Further, as the 

 East African dinosaurs are so very much like those of the Morrison, 

 and as this is especially true of the sauropods, the evidence appears to 

 indicate that all of these animals are of Upper Jurassic age. Accord- 

 ingly the Morrison may be of this time; but as these saurians are also 

 related to the ven^ fragmentary ones of the Wealden, which are of early 

 Comanchian time, it seems best at present not to be too quick in accept- 

 ing the view that the ^lorrison is Jurassic. 



The Morrison and Sundance Formations 



xalles applied to the morrison 



The Morrison formation of the Great Plains is widely known as the 

 one which has furnished since 1877 the most striking of all fossil ani- 

 mals, the great dinosaurs. They were first successfully collected near 

 Morrison and in Garden Park, near Canyon City, Colorado ; later at Como 

 Bluff and elsewhere in AYyoming, and most recentl}^ in Utah. At first 

 these deposits were known as the Atlantosaurus beds, a name given them 

 by Marsh ; later they were called the Como beds by Scott, the Gunnison 

 formation by Eldridge, and the McElmo and the Morrison formation by 

 Cross ; the last term, proposed in 1894, is now in general use. 



CHARACTERISTICS AND DISTRIBUTION 



The Morrison of eastern Colorado and central Wyoming, Stanton 

 writes, ^ 



o' 



''consists of variegated marls and shales witli irregular beds of sandstone and 

 sometimes thinner layers and lenses of siliceous limestone. The colors of the 

 shales and marls are greenish gray, purplish, maroon and red, very irregularly 

 distributed, while the sandstones are usually gray, sometimes weathering 

 brown or with small brown spots." 



The sandstones often channel into the clays and then occur as lenses, 

 and it is very probable that most of the red color of the shales is due to 

 secondar}^ causes or weathering. 



"The limestones are gray, in some cases weathering with a reddish tinge. 

 The general appearance of the formation is remarkably uniform over large 

 areas, and yet the individual elements are so variable that no two detailed 

 sections are exact duplicates of each other." 



2 T. W. Stanton : The Morrison formation and its relation with the Comanche series 

 and the Dakota formation. Jour. Geology, vol. 13, 1905, pp. 657-658. 



