440 G. F. LOUGHLIN 
Survey map, a rudely elliptical mass of granite surrounded on three 
sides by a concentric succession of sedimentary rocks. The granite, 
originally called Archean, was proved by Mr. Emmons in 1903! to 
be intrusive and probably of post-Jurassic age and his conclusions 
have been sustained by Boutwell.2 The sedimentary rocks were 
originally correlated as follows: 
Permo-Carboniferous and later 
Upper Coal Measures limestone 
Weber quartzite, Carboniferous 
Wasatch limestone (intercalated series at the top), mostly lower Coal 
Measures 
Ogden quartzite, Devonian 
Ute limestone, Silurian 
Quartzite (clay slates at the top), Cambrian 
The present writer, however, during his first day in the district 
found fossils in the lower limestone belt (called the “Ute” in the 
above table) of Madison (Lower Mississippian) age. These 
fossils were collected on the spur between the two cirques just over 
the divide northwest of Alta, and were determined by Dr. Girty 
of the Survey as follows: 
Syringopora sp. Syringothyris (?) sp. 
Zaphrentis sp. Composita sp. 
Amplexus sp. Cleiothyridina crassicardinalis 
Spirifer centronatus Euomphalus sp. 
These fossils are in part duplicated by fossils found in the 
great upper limestone belt (the “Wasatch” limestone of the 
Fortieth Parallel Survey), the greater part of which appears to be of 
Madison age. The fossils collected from this belt were determined 
by Dr. Girty as follows: 
Syringopora sp. 
Zaphrentis sp. 
Spirifer centronatus 
The presence of two belts of Mississippian limestone separated 
by a quartzite belt at once suggested the presence of an overthrust 
fault, which is proved by the following evidence. The “lower” 
limestone extends northward for about half-way down the Mill D 
tS. F. Emmons, Amer. Jour. Science, 4th series, XVI (1903), 139-47. 
2J. M. Boutwell, of. cit., p. 156. 
