446 N. H. DARTON PALEOZOIC AND MESOZOIC OF "WYOMING 



Feet 



Blue shale 50 



Limestone 2 



Concealed, probably blue shale 30+ 



Total 135+ 



In Bed moiintain, Avhere the formation is 128 feet thick, it consists 

 niainl}' of pale l)luish shale, which in the upper beds contains green nodu- 

 lar masses. Thirty-six feet above the base there is a 2-foot layer of lime- 

 stone, and 88 feet above the base a 1-foot limestone layer containing fresh- 

 water fossils. At the base are light colored sandstones and terra cotta 

 and bluish shales, which may possibly represent the marine Jurassic, but, 

 as they contain no fossils, they are provisionally classed as Chugwater. 



East of Laramie mountains. — In the first canyon south of South fork 

 of Horse creek the Morrison consists of pale green and maroon massive 

 shale lying on 30 feet of light colored massive shale containing several 

 layers of limestone, one 6 feet thick. On South fork of Horse creek the 

 6-foot limestone member is conspicuous, underlain by 20 feet of gray 

 shale lying on a 1-foot limestone bed at supposed base of the formation. 

 The total thickness here is about 200 feet, which appears to be the average 

 amount, except on the southernmost prong of Horse creek, where it is 

 less than 150 feet. 



Fossils and age. — Many dinosaur remains have been obtained from 

 the Morrison formation in southeastern Wyoming, notably from the 

 extensive bone quarries near "Bone Cabin," in the northeastern jjor- 

 tion of Freezeout hills, 15 miles north by west from Medicine Bow; on 

 Rock creek east of Medicine Bow; on Sheep creek; on Como ridge, 

 6 miles east of Medicine Bow, and on Bone creek, 7 miles northeast 

 of Medicine Bow. They comprise Brontosaurus, Morosaurus, Lao- 

 saurus, Camptosaurus, Dryosaurus, Ornitholestes, Diplodocus, Stego- 

 saurus, and Allosaurus. Collections have also been made near Steam- 

 boat lake, southwest of Laramie. Bones have been found also at a 

 ])oint 2 miles east of Red mountain, west of Downey lake, east of Jelm, 

 and also at several localities in Colorado a short distance south of the 

 state line. In the drab, brittle, impure limestones in the shales are 

 numerous remains of fresh-water molluscs, usually of very small size. 

 Fossil algse occur in the limestones along the east side of Laramie moun- 

 tains. The following fossils were identified by Dr T. W. Stanton from 

 west and southwest of Laramie : Unio baileyi, Limnaa, Planorbis veter- 

 nus, Volvata scabrida, Vorticifex stearnei, Viviparus, ? and Viviparus 

 n. sp. (very large) ; and from Como ridge: Unio sp., Volvata scabrida. 

 and Limncca accelerata. In the thin layer of brown sandy limestone in 



