568 INDEX TO THE STEATIGEAPHY OF NORTH AMEEICA. 



Section of Sundance formation on Owl Creek 7 miles northwest of Thermopolis , Wyo, 



Feet. 



Green soft sandy shales and hard greenish fossilif erous sandstone in alternating layers 70 



Gray sandstone 4 



Green sandy clay '. 20 



Gray limy sandstone _ 2 



Dark greenish-gray sandy clay, with many belemnites 40 



Greenish-gray sandstone, with occasional hard layers 30 



Green sandy shale 20 



Greenish-gray sandstone, thin bedded 4 



Hard buff impure limestone, breaking into small rectangular blocks 2 



Green sandy shale lying on "Red beds '' 2 



194 



Along the slope of Wind River Mountains and in the upUfts passing east of Fort Washakie 

 and Lander the Sundance formation is about 300 feet thick and consists of greenish-gray shales 

 and sandstones, with thin but prorainent ledges of impure, highly fossiliferous limestone in 

 their upper part. In the northern foothills of the Rattlesnake Mountains, where the thickness 

 is about 300 feet, there are gray sandstones at the top, and part of the medial sandy shales are 

 of pronounced reddish tint, as in the Black Hills and some other districts in Wyoming. 



Platte Valley to RocTc River. — The Sundance formation presents most of its usual features 

 along the south side of Casper Moiintain, in Muddy Creek valley, and on Wagonhound Creek 

 and North Platte River south of Douglas. In the extensive exposures in the big bend of the 

 river south of Douglas there are 30 feet or more of massive gray sandstone, overlain by 30 feet 

 of pale-greenish sandy shale, 5 feet of soft greenish massive sandstone, 40 feet of soft sandstones 

 of bright-reddish tint, 15 feet of massive buff sandstone, and about 200 feet of green shale with 

 three hard beds of fossiliferous limestone. * * * 



Section of Sundance formation near Alcova, Wyo. 



Feet. 



Green shale 65 



Slabby, hard limestone 10 



Green shale 10 



Limestone 10 



Green shale 75 



Sandstone 5 



Shale, part pink, part green 100 



Sandstone, white (on Chugwater red beds) 25 



300 



In the Freezeout Hills and Rock River region the lower beds of the formation are pre- 

 dominantly sandy, wliile the upper part consists largely of green shales with hard fossiliferous 

 layers. In an extensive exposure east of Medicine Bow the strata are as follows: 



Section of Sundance formation in Como Ridge, 6 miles east of Medicine Bow, Wyo. 



Morrison shales. Feet. 



Limestone and shale 15 



Massive disintegrated sandstone, in part shaly 10 



Drab shale with few lumps of brown limestone 30 



Buff shaly sandstone 5 



Yellow sandy shale with belemnites 42 



Buff shaly sandstone 5 



Yellow shale (lying on the Chugwater red beds) 12 



119 



A section in the eastern side of the Freezeout Hills near Dyer's ranch, given by W. N. Logan, 

 is as follows : 



