NO. 14 A NEW SAUROPOD DINOSAUR GILMORE 5 



a number of units named in ascending order as follows : Dakota sandstone, 

 Mancos shale, Point Lookout sandstone, Menefee formation, Cliff House 

 standstone, Lewis shale, Pictured Cliffs sandstone, Fruitland formation, Kirt- 

 land shale with included Farmington sandstone member, Ojo Alamo sandstone, 

 Puerco formation, Torrejon formation, and Wasatch formation. The Point 

 Lookout sandstone, Menefee formation, and Cliff House sandstone comprise 

 the Mesaverde formation of the older literature and the Pictured Cliffs sand- 

 stone, Fruitland formation, and Kirtland shale, the Laramie formation. The 

 Dakota sandstone contains coal beds and other plant remains and grades into 

 the overlying Mancos shale. The formations from the Mancos shale to the 

 Pictured Cliff's sandstone, inclusive, are marine except parts of the Menefee 

 formation which arc brackish and fresh water deposits with coal beds. The 

 lower part of the Fruitland formation contains a transition series of brackish 

 water beds and the upper part and all of the overlying formations are fluviatile 

 deposits. The Mancos shale represents in large part the Benton shale and 

 Niobrara formation of the region east of the Rocky Mountains. Its extreme 

 upper part, however, is the equivalent of the basal part of the Pierre shale. 

 The Mesaverde group, Lewis shale, and Pictured Cliffs sandstone contain 

 invertebrates of Montana age, and the Fruitland and Kirtland formations, 

 plants, invertebrates, and reptiles of Montana age. These beds definitelj'^ 

 assignable to the Upper Cretaceous, /. c, from Dakota sandstone to Kirtland 

 shale, inclusive, are a comformable series 5,500 feet thick, of which about 

 4,000 feet are of Montana age. The age of the Ojo Alamo sandstone is in dis- 

 pute. It has been assigned by some writers on the basis of its dinosaur fauna 

 to the Montana group and correlated with the Judith River beds. It is 

 separated from the Kirtland shale by a widespread luiconformity and has been 

 correlated on that ground by other writers with the Denver and Raton forma- 

 tions of post-Montana age. The Puerco and Torrejon formations contain 

 large mammalian faunas and are usually placed in the Tertiary, though some 

 writers would place them in the Cretaceous. The Wasatch formation is uni- 

 versally accepted as Tertiary. 



Dinosaur remains have been found in the Fruitland formation, throughout 

 the Kirtland shale, and in the Ojo Alamo sandstone. The sauropod bones 

 found in June, 1921, came from the lower part of the Ojo Alamo sandstone 

 on Barrel Spring Arroyo, one mile south of Ojo Alamo. A detailed section 

 at this locality is as follows : ^ 



Ojo Alamo sandstone: Feet 



Sandstone, conglomeratic ; top eroded I5-|- 



Shale, dark greenish gray 7 



Sandstone, soft, nearly white, crossbedded ; contains gray argilla- 

 ceous streaks and brown concretions 21 



Shale, wine red, with local gray sandstone lenses 5 



Sandstone, soft, white, crossbedded ; contains brown concretions in 



the lower part 10 



Sandstone, brown, platy, ferruginous i 



Shale, dark bluish gray to purple, sandy 4 



^ See Bauer, C. M., Stratigraphy of a part of the Chaco River Valley. U. S. 

 Geol. Survey Prof. Paper 98, pi. 69 and pi. 70, 1916. This locality is shown 

 as locality 67 on plate 69 and the stratigraphic section as section R on plate 70. 



