PARK ACIDAG MINING DISTRICT. UTAH: 455 
Camptonectes pertenuistriatus Hall & Pinna kingi Meek. 
Whitfield. Cyprina? sp. 
Cucullaea haguet Meek ? Pentacrinus sp 
Astarte sp. Ostrea sp. 
Pleuromya subcompressa Meek. Lima (Plagiostoma) occidentalis Hall & 
Cerithium? sp. Whitfield. 
Nerinea sp. Gervillia sp. 
Gryphaea calceola var. nebrascensis M. 
Well 
GENERAL STRUCTURE 
In the course of mapping the above-described geologic formations 
in this district, and of reconnaissance work in adjoining areas, several 
structural features were discovered which bear significantly upon the 
location and deformation of the ore-bearing formations. Some time 
must necessarily elapse before the complete report giving these results 
can appear. Accordingly, in response to several urgent requests 
from operators for information, this opportunity is taken to present 
without further delay a general statement of some of the more impor- 
tant structural features. 
The general anticlinal structure of the Paleozoic and Mesozoic 
beds which characterize the Wasatch as a whole is interrupted in this 
central portion by a transverse (east-west) anticline or dome. Sedi- 
ments ranging from Cambrian to Tertiary here dip northerly and 
southerly quaquaversally from a series of laccolithic masses. These 
include, from west to east, the porphyritic granite of Lone Peak and 
Little Cottonwood Canyon, the granodiorite at the head of Little 
Cottonwood Canyon in the vicinity of Alta, the coarse and fine-grained 
dioritic masses at the heads of Big and Little Cottonwood Canyons, 
and the northeast extensions in the form of dikes. These several 
masses constitute a mammoth composite laccolith. It is noteworthy 
that these intrusions have taken place along a zone coinciding in 
location and course with the extension of the Uinta axis across the 
Wasatch. ‘This fact, together with the influence of these masses in 
doming the structure athwart the general course of the Wasatch, 
naturally raises a query as to a similar influence in the formation of 
the Uintas. This transverse Wasatch dome and the Uinta dome are 
separated topographically, though not structurally, by a north-south 
