PARK CITY MINING DISTRICT, UTAH 435 
exposed in Big Cottonwood Canyon, were carefully measured and 
critically studied. Among the results secured is the precise definition 
of several stratigraphic formations, including one carrying a previously 
undescribed Permian fauna; also the solution of several faults of 
large offset which bear significantly upon mining operations. 
Three brief progress reports have been published. The com- 
plete statement of the results of that investigation will go to press this 
year in the form of a “Professional Paper” of the United States 
Geological Survey. It seems desirable, however, that certain results 
should be made public at once. This paper has therefore been pre- 
pared by request for the purpose of introducing the names of certain 
stratigraphic formations for the use of writers on these formations in 
adjacent regions, and of rendering the broad, structural results of 
the work available for use by local operators. 
In this connection it is a pleasure to acknowledge the valuable 
contributions toward these final conclusions. Thus, the investiga- 
tion has throughout been under the general supervision of Mr. S. F. 
Emmons, and in the first year was carried on jointly by Dr. J. D. 
Irving and the writer, and during the remaining two years benefited 
by the service of Mr. L. H. Woolsey. Dr. T. W. Stanton has identified 
the fossil collections from the Jurassic and Triassic, and also in 1903 
kindly co-operated in the field in the solution of special problems of 
stratigraphic correlation; while Dr. G. H. Girty has determined the 
fossil collections from the Carboniferous, numbering over too dis- 
tinct lots, and throughout the investigation has given helpful inter- 
pretations of paleontological evidence. The writer began his work 
in the region in October, 1900, when it was his good fortune to dis- 
cover material proof that the main Little Cottonwood granite mass is 
intrusive in quartzite of Cambrian age, and that the Alta granodiorite 
body is intrusive in limestone of Pennsylvanian age.’ In addition 
to the detailed study of the immediate Park City District throughout 
the period of survey, he has also carried on comparative studies in 
stratigraphic correlation and general geology in adjoining portions of 
this range and the Uintas. 
1S, F. Emmons, “ Little Cottonwood Granite Body of the Wasatch Mountains,”’’ 
American Journal of Science, Vol. XVI (August, 1903), pp. 139-47. J. M Boutwell, 
‘Progress Report on Park City District, Contributions to Economic Geology 1902,” 
U. S. Geological Survey, Bulletin, No. 213 (March, 1903), p. 36. 
