THE BANNOCK OVERTHRUST 689 
been studied by Dr. Girty, who has selected the following charac- 
teristic list from his bulletin (12) on the subject: 
Lingula carbonaria (?) 
Lingulidiscina missouriensis 
Chonetes ostiolatus 
Productus geniculatus 
Productus eucharis 
Productus montpelierensis 
Productus phosphaticus 
Pugnax weeksi 
Pugnax osagensis var. occidentalis 
Ambocoelia arcuata 
Leda obesa 
Plagioglypta canna 
Omphalotrochus ferrieri 
Omphalotrochus conoideus 
Hollina emaciata var. occidentalis 
The distribution of the Phosphoria formation, so far as at present 
known, is limited to portions of southeastern Idaho, northeastern 
Utah, and western Wyoming. 
WELLS FORMATION 
The Phosphoria formation is normally underlain by 2,400 feet 
of sandy limestones, calcareous sandstones, and quartzites of some- 
what variable character. These beds are here grouped in a forma- 
tion whose name is derived from Wells Canyon in T. 10 S., R. 45 E., 
on the north side of which a detailed section was measured. The 
stratigraphic interval is probably the same as is represented by the 
Morgan, Weber, and a portion of the Park City formations of 
northeastern Utah. In the Idaho field, however, these rocks show 
such variable lithologic features that it has been found impracticable 
to apply successfully the names Weber and Morgan over a major 
portion of the area. Furthermore, Dr. Girty comments that 
there is no faunal assurance that these divisions as recognized are 
actually the equivalents of the formations in Weber Canyon, 
Utah. Faunal and structural grounds make it advisable to include 
