LOWER CRETACEOUS. 607 



the formation is called Jurassic ( ?) in recent publications of the United States 

 Geological Survey. Its relations to the Comanche series were traced by Stanton/*' 

 with W. T. Lee and C, W. Gilmore, and are expressed in the following comments 

 and sections : 



The beds now generally designated on United States Geological Survey niaps as the 

 Morrison formation have been a subject of interest and discussion since 1877, when abundant 

 remains of dinosaurs were found in them. The first extensive collections of the vertebrate 

 fauna were obtained in the neighborhood of Morrison near Denver, in Garden Park, near 

 Canon City, Colo., and at Como or Aurora, Wyo. Since then the formation has been recognized 

 by means of its fossils, its lithologic features, and its stratigraphic relations in the Black HUls, 

 on the Laramie Plains, and elsewhere in Wyoming, in Montana, in western Colorado, in south- 

 eastern Colorado, and in adjacent parts of Oklahoma and New Mexico. * * * 



The formation is nonmarine throughout, so far as known, and consists of variegated marls 

 and shales with 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 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 

 duphcates of each other. The total thickness is seldom more than 200 feet, though it is 

 possibly more than 400 feet at Canon City. 



Several geologists, particularly Hill and Lee, having suggested that the 

 Morrison was a representative of some part of the Comanche series, Stanton examined 

 its relations, as stated above, and found: 



Section on Purgatoire River about 20 miles south of La Junta, Colo. 



Feet. 



1. Benton shales, thickness probably not more than 200 



2. Dakota sandstone 100 



3. Dark shales and shaly limestones with Comanche fauna 50-100 



4. Coarse gray cross-bedded sandstone 15-60 



5. Variegated shales, marls, sandstones, and limestones of the ilorrison formation, with Bron- 



tosaurus, etc 200 



6. Gypsum and gypsiferous shales 70-125 



7. Red Beds with Belodon near top, exposed 200-300 



Section on Rio Cimarron east of Garrett post office, Olda. 



Feet. 



1. Massive coarse cross-bedded gray and brown sandstone of the Dakota 150 



2. Dark shales with layers of brown flaggy sandstone and bands of somewhat calcareous 



yellow sandstone with Comanche fauna 50-60 



3. Coarse brown or gray cross-bedded sandstone with irregular bands of pebbles, apparently 



unconformable on the underlying stratum 4-15 



4. Variegated shales, gray sandstones and bands of siliceous limestone, referred to the Morri- 



son, not well exposed. Thickness probably less than 100 



5. Red Beds. 



The Comanche horizon has yielded a varied fauna which is clearly the same as the Wasliita 

 fauna that has long been known as Mesa Tucumcari, New ]\lexico, in northern Texas, and in 

 the Kiowa shales of southern Kansas. * * * 



This horizon was traced with practical continuity westward up the Cimarron to Folsom, 

 New Mexico, a distance of about 75 miles across the strike. Its lithologic features show little 

 variation, and its thickness is never less than 50 feet nor more than 100 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 

 Gryphxa corrugata was collected is about 30 miles east of Folsom. 



Along this line the coarse sandstone beneath the Comanche fossils is from 15 to 40 feet 

 in thickness, and the variegated shales, sandstones, etc., of the Morrison increase to about 200 



