boutwell] ORE DEPOSITS OF BINGHAM, UTAH. 117 
Gauge mines on the north to the Queen and Lucky Boy mines on the 
south, an area of approximately 15 square miles. The vertical range 
of known ore deposits is marked by those in the Zelnora (8375) and 
the lowest levels in the Brooklyn (5875) and Dalton and Lark (5810), 
a vertical extent of 2,565 feet. 
Ore bodies occur in each of the lithoiogic types of rocks of the dis- 
trict, including limestones, quartzite, shale, and ijorphyry. The lime- 
stones, which have afforded the largest ore bodies, compose the main 
belt and include the Brooklyn-Telegraph and the Commercial and 
Highland Boy members. No ore bodies are known in the massive 
dark-blue limestone underlying these series, but some have been 
found in the siliceous limestone above the Highland Boy horizon and 
in the thin mottled limestone of the Petro-York "bedded vein." 
Although ore occurs in the calcareous shales which characterize the 
great siliceous series over the main limestone belt, exploration shows 
that the rich lead-silver bodies formed under rather than within these 
shales. High-grade lead-silver ore carrying minor values of copper 
and gold occur in fissures which transect the quartzite, porphyry, or 
shale. 
If we may judge from the occurrence of known ore bodies, two litho- 
iogic types appear to have exerted the strongest influence upon their 
formation, namely, limestone and porphyry; for it is in the main lime- 
stones in the neighborhood of intrusive masses that the large shoots 
of copper sulphides have been discovered. Thus the country rock 
inclosing the great Highland Boy shoots overlies a broad, irregular 
dike sill. The newly proven shoot in the Boston Consolidated over- 
lies the great Last Chance intrusive, and is cut and overlain by por- 
phyry. The bodies in the Jordan-Telegraph-Brooklyn and in the 
Commercial- Yosemite limestones are complexly associated with dikes 
and sills. 
In influencing the position, form, and extent of ore bodies, defor- 
mation of the country rock appears to have constituted a third impor- 
tant factor in the formation of ore bodies, for in Bingham those 
limestones which have been intruded by porphyry inclose the larger 
and more numerous shoots in regions in which strong fracturing and 
Assuring have occurred. The entire country rock is excessively frac- 
tured, crushed, and fissured. These fissures are distinct loci of move- 
ment, of considerable horizontal and vertical extent, bounded by 
highly slickensided and polished walls, and possess in a general way 
the form of planes, but in detail exhibit many inequalities. They 
are not restricted to a few distinct trends, but trend in about equal 
number toward practically all points of the compass. 
The ore-bearing fissures, however, in far the greater number trend 
toward the northeast and southwest, and dip steeply to the northwest. 
Underground evidence shows that Assuring took place in northeast- 
