THE MORRISON FORMATION 665 



feet. Fossils gradually become less abundant in both species and 

 individuals toward the west, until near Folsom only a small mactroid 

 shell was found in considerable numbers. The most western point 

 at which Gryphaea corrugata was collected is about thirty miles east 

 of Folsom. 



Along this line the coarse sandstone beneath the Comanche fossils 

 is from fifteen to forty feet in thickness, and the variegated shales, 

 sandstones, etc., of the Morrison increase to about 200 feet. Litho- 

 logically and stratigraphically this is identical with the Morrison beds 

 seen on the Purgatoire where characteristic dinosaurs were collected. 

 Fragmentary, undetermined, dinosaur remains were seen in it on the 

 Cimarron near Exter, New Mexico. 



Beneath the recognized Morrison some localities show forty to 

 fifty feet of gypsum and gypsiferous shales resting on a massive white 

 or pinkish sandstone which Mr. Lee has described as the Exter sand- 

 stone. It varies greatly in thickness, the maximum observed being 

 eighty feet. The Exter is separated from the Red Beds by a striking 

 angular unconformity, wherever the Red Beds are folded in local 

 uplifts. The Red Beds show the usual character and at Tod's ranch, 

 fifteen miles east of Folsom, they yielded fragmentary Triassic verte- 

 brates. 



From Folsom we traveled by rail to Tucumcari and from that 

 place by wagon to Las Vegas. 



Tucumcari region.— At Mesa Tucumcari the Dakota sandstone, 

 eighty feet in thickness is underlain by sixty feet of fossiliferous 

 Comanche shales and yellowish sandstones containing the same fauna 

 as at Garrett, Oklahoma, with a few additions. The Morrison 

 formation was not recognized but its place in the section is occupied 

 by a talus slope with no exposures. The lower part of the section 

 is composed of Red Beds of the ordinary character, overlain by 

 friable, light-colored sandstone that is suggestive of the Exter. 



At Mesa Redondo, a few miles south of Tucumcari, the space 

 between the Comanche zone and the Red Beds is filled by 300 feet 

 of heavy bedded gray and buff sandstones with intercalated thinner 

 beds of red shales. 



About ten miles northwest of Tucumcari station the section shows 



1 Journal of Geology, Vol. X (1902), p. 45. 



