50 C. R. Longivell — Geology of 



The following forms, found in the limestones, were 

 identified by Dr. Girty: Aviculipecten utahensis, A. spp. 

 1 and 2, A.m. sp., Pseiidomonotis n. sp., Myalina n. sp., 

 Pteriaf sp., Sedgivickiaf n. sp., Myophoria n. sp., M. aff. 

 lineata, Pleurotomariaf n. sp., Pleuropliorusf n. sp., 

 Pseudomelaniaf n. sp., Murcliisoniaf sp., and casts of 

 starfishes. 



Although this list is not diagnostic in itself, it serves to 

 correlate the horizon with beds in Arizona, Utah, and 

 Idaho in which, Dr. Girty states, ammonites have been 

 found, proving a Lower Triassic age for the horizon. 

 Very clearly the formation corresponds closely to the 







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Fig. 5. — Unconformable contact of Pliocene (?) intermontane deposits and 

 Horse Spring beds. Valley of Muddy Creek. 



Kanab Valley * ^ Permian, ' ' to the ^ ^ Lower Shinarump ' ' of 

 northern Arizona, and to the Moenkopi formation of 

 Arizona, New Mexico, and Utah. The name Moenkopi 

 has been applied to the beds of this horizon over a large 

 region, and this name will also be used here for the for- 

 mation in the Muddy Mountains, inasmuch as there is no 

 reasonable doubt regarding the correlation. 



A disconf ormity separates the top of the Moenkopi for- 

 mation from the Shinarump conglomerate, which ranges 

 in thickness from 10 feet to 200 feet and varies in compo- 

 sition from coarse conglomerate to conglomeratic sand- 

 stone. Pebbles are mainly quartzite and chert, and are 



