152 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213. 
steeply and are in places nearly vertical. East of Bisbee the faults 
are normal, but southeast of Mule Pass Gulch faults of the reversed 
or overthrust type predominate. As Tertiary sediments are absent in 
the Bisbee region, this period was probably marked by the deforma- 
tion of the Cretaceous and older rocks and by erosion. 
The Pleistocene is represented by unconsolidated gravelly deposits 
flooring the broad valleys that surround the Mule Mountains on the 
west, south, and east. These are in the main fluviatile wash, with 
possibly some finer lacustrine beds at a distance from the mountains. 
It is impossible without the aid of a geological map to do more than 
indicate very crudely the general distribution and structure of the 
rocks of the Bisbee quadrangle. A northwest-southeast diagonal 
drawn through the quadrangle will pass through the town of Bisbee 
and form a rough division between the Cretaceous beds on the north- 
east and the pre-Mesozoic rocks on the southwest. The former, 
although folded and faulted, exhibit simple structures and have a 
prevalent dip to the northeast, away from the older rocks. They 
undoubtedly once extended farther over the Paleozoic rocks to the 
southwest, but have been removed by Tertiary and Pleistocene erosion. 
In contrast with the Cretaceous beds, the Paleozoic and pre-Cambrian 
rocks exhibit a highly complex structure, which, if we disregard the 
undecipherable pre-Cambrian deformation of the crystalline schists, is 
due to faulting, to intrusions of granite-porphyry, and to folding. In 
the northwestern part of the quadrangle the Paleozoic beds dip gen- 
erally to the southwest, but they change near Bisbee to a southeast- 
erly dip, which in turn swings round to a northeasterly dip a few 
miles southeast of the town. The pre-Cambrian schists, which are 
extensively exposed in the northern part of the district, pass gradu- 
ally beneath the Paleozoic beds to the southwest, being less and less 
frequently exposed in the various fault blocks, and finally disappear- 
ing altogether toward Naco Junction. 
DEVELOPMENT AND PRODUCTION. 
Prior to the year 1880 Bisbee was an unimportant lead camp, a 
single furnace being then in operation upon cerussite mined from the 
Hendricks claim, close to town. The copper ore of the Copper Queen 
mine was discovered early in this year, and was profitably exploited 
until 1881. This ore was free from sulphur and had an average tenor 
of 23 per cent of copper. It was treated in two 36-inch furnaces, 
which, in spite of their small size were able, with wood as fuel, to 
turn out about half a million pounds a month. In 1882 the men com- 
posing the present Copper Queen Company bought the Atlanta claim 
near the original discovery and began prospecting. 
In 1884 the Copper Queen ore body, which had been worked for 
300 feet down an incline, was exhausted. The outlook was gloomy 
and work was almost abandoned, when a second ore body was simul- 
