MOOK, STUDY OF THE MORRISON FORMATION 93 



Jurassic [Morrison and Sundance] Feet 



Bluish green clay 21 



Green clay 20 



Flint 1/3 



Gray sandstone 10 



Concretions 2 



Green clay 3 



Concretions 1% 



Green clay 8 



Green clay with concretions 10 



Maroon clay with small concretions 10 



Sandstone 3 



Green clay 8 



Sandstone 1 



Red clay 5 



Sandstone 2 



Green clay -. 6 



Sandstone 1% 



Red, green, maroon clay 12 



Sandstone 2 



Maroon, green, red clay 10 



Sandstone 2 



Green clay 22 



Sandstone 1 



Green clay 20 



Reddish clay 20 



Sandstone 1% 



Green sandy shale 6 



Purple clay with limestones 22 



Nucula limestone 1 



Brown clay 43 



Total of Jurassic [Morrison and Sundance] 274 5/6 



In these sections the Morrison is interpreted as beginning with 'No. 13. 

 The contact is not very distinct. 



Logan gives the following section for the Freezeout Hills (1900, 5) : 



"Purplish clay containing considerable arenaceous inclusions 40 ft. 



"The clay contains, in the lower part, a thin stratum of sandy limestone in 

 which the following fossils were found : Pentacrinus dsteriscus, Asterias 

 duMum, Pseudomonotis curta, Avicula macronatus, and Ostrea strigilecula. 



"The Atlantosaurtts Beds. — The last stratum is the last one containing ma- 

 rine fossils, and probably closes the Jura, but some of the non-fossiliferous 

 beds lying above may belong to that formation. The succeeding stratum 

 varies so much in thickness that it may represent the eroded surface of the 

 Jura upon which the Atlantosaurus Beds were deposited. 



"16. Fine-grained, grayish-white sandstone 10 ft. to 125 ft. 



"The above stratum varies much in thickness within short distances. At 



