JURASSIC SYSTEM 441 



Section of Sundance Formation in Como Ridge, 6 Miles East of Medicine Bow, 



Wyoming 



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, shalj' sandstone 5 



Yellow shale (lying on Chugwater red beds) 12 



Total 119 



Two miles north of Medicine Bow tlie lower half of the formation is a 

 massive buff sandstone, with 8 feet of red shale about 100 feet above its 

 base and a 2-foot bed of red shale a short distance higher. 



A section in the eastern side of the Freezeout hills near Dyer's ranch, 

 given by W. Jf. Logan/* is as follows : 



Section of Sundance Formation in Freezeout Hills, Wyoming 



No. Feet 

 15. Purplish clay with sandy inclusions (has sandy lime- 

 stone layer near base filled with fossils) 40 



14. Greenish sandstone, thinly laminated 2-5 



13. Purplish, fossiliferous clay, with many lime nodules 



filled with fossils 20 



12. White, sandy clay, dinosaur remains 4 



11. Sandy clay with brown concretions; green sandstone 



layer near middle 6 



10. White, sandy limestone in thin layers (fossils) % 



9. Sandy red clay 10 



8. White, fissile sandstone 6 



7. Shale, reddish, changing to purple 4 



G. White sandstone, moderately hard % 



2-5. White sandstones, separated by 2 layers of red clay. . . 1 

 1. Red clay of Chugwater formation. 



Total 94+ 



East of Laramie mountains. — The thin margin of the Sundance forma- 

 tion outcrops continuously along the eastern foothills from JTorth fork of 

 Horse creek to the southernmost prong of Horse creek and from tbe 

 North to the South fork of Lodgepole creek. Small exposures appear on 

 North and Middle forks of Crow creek. The rocks are mostly light buff 

 sandstones, but some sandy shales appear. The average thickness is 40 



" Kansas University Quarterly, vol. Ix, 1900, pp. 111-112. 



