MOOK, STUDY OF THE MORRISON FORMATION 



61 



Feet 



Sandstones of the Purgatoire formation. 



Variegated shale and compact argillite, green drab, and dull maroon in 

 color, largely covered 37 



Massive gray sandstone having ocher colored spots, with soft fine- 

 grained chocolate colored sandstone above and red layers toward the 

 top. Largely covered. Exact relation not known 58± 



Greenish-gray shale and compact argillite with 6-inch beds of impure 

 limestone and short lenses of sandstone. The limestones contain 

 small fresh-water gastropods and lamellibranchs 25± 



120± 



Two miles above the mouth of Jones Lake Fork 

 there is an exposure of 100 feet of the formation. 

 The uppermost beds at this point are covered, but 

 there is about 30 feet of reddish shale with cal- 

 careous concretions, underlain by 8-10 feet of lime- 

 stone. At the base is green argillite. 



Gilbert gives the following partial section at the 

 mouth of Jones Lake Fork (Stose, 1912, 7) : 



Feet 

 Thin sandstone and gray shale (Purgatoire for- 

 mation). 



Chocolate colored shale 16 



Soft pale gray sandstone freckled with brown, 



weathering pale brown 10 



Variegated compact blocky shale, red, chocolate, 

 green and white, with bands of fine sandstone, 

 some tough and brown. The lowest sandstone 

 is a fine-grained rock freckled with pale yellow . 51 



77 



EASTERN NEW MEXICO AND OKLAIIOMA 



Fig. 19. — Composite sec- 

 tion of the upper part 

 of the Morrison forma- 

 tion in the Huerfano 

 quadrangle, Colorado. 



1. — ■ Purgatoire ; 2. — 

 Morrison. Scale, 125 feet 

 to 1 Inch. (Stose.) 



The Morrison occurs a few miles east of Fol- 

 som, New Mexico, in the canyon of the Eio Cimar- 

 ron (Lee, 1902, 5). It consists, at this point, of 

 25 to 50 feet of variegated clay-shales overlying the upper gypsum mem- 

 ber of the Eed Bed series. These clays thicken -^farther east, and 14 miles 

 east of Folsom they are about 200 feet thick. The following section by 

 Lee was measured at this point: 



Dakota (Purgatoire). Sandstone, massive and quartzitic, somewhat conglom- 

 eratic in places. 

 Shales (Morrison). 200 feet of varicolored shales with local bedsi of brittle 

 limestone and lime concretions. A coarse, loose-tex- 

 tured, cross-bedded sandstone occurs near the top. 

 . Red Beds. Deep red sandstone. 



