MOOK, STUDY OF THE MORRISON FORMATION 



109 



Feet 



Maroon clay with small concretions 6 



Green clay : 15 



Maroon clay witli small concretions 12 



Green clay 6 



Limestone concretions 1 



Olive green clay 8 



Buff sandstone 12 



111 



'•'"''r'r^'*'"-'-- ■•^'^ •^' •'l'-^ 

















































































































"'.'-==-i^'5I---r.-. 















































Fig. 76. — Section of the Morrison forma- 

 tion at Kara Peak, Wyoming. 



Scale, 125 feet to 1 inch. (Loomis.) 



Fig. 77. — Section of the Morrison forma- 

 tion on Bearer Creek, Wyoming. 



Scale, 125 feet to 1 inch. (Loomis.) 



Atlantic Coast Eepresentative of' the Morrison Formation 



ARUNDEL formation OF MARYLAND 



The Morrison formation is apparently represented in the eastern part 

 of the United States by part of the Potomac series. It was formerly 

 claimed that the Potomac was a unit formation. Its age has been disr 

 cussed by a number of workers, some holding it to be Jurassic, others 

 Cretaceous. More recently it has been divided into several distinct for- 

 mations, separated from one another and from the underlying and over- 

 lying formations by disconformities or stratigraphic breaks. The lowest 

 formation of the Potomac series, the Patuxent, contains none of the dino- 

 saurian fauna characteristic of the Morrison, but the middle member, or 

 Arundel, is characterized by many forms identical with or closely related 

 to the forms of the Morrison fauna. The Arundel beds have been well 

 described by Clark, Bibbins and Berry (1911, 5). 



The Arundel is the lower part of the "upper oolite," or "Iron-Ore 

 Clays" of Tyson, a part of the "Variegated Clays" of Fontaine and Mc- 

 Gee, and of the "Baltimorean" of Uhler. It is the equivalent of the 

 "Iron-Ore series" of Ward. It outcrops in an irregular northeast-south- 



