24 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213. 
The Bradshaw quadrangle contains important deposits of both cop- 
per and gold in the same series of rocks in which those of the United 
Verde occur, but developments on most of them had, unfortunately, 
not been pushed to any great depth. The ores occur mainly as vein 
deposits in old Algonkian schists associated with eruptives. One 
important result of the work has been to detect a tendency in the ore 
deposits to arrange themselves peripherally around the bosses of the 
granite which outcrop in the area. The results of this work will be 
published in f^lio form. 
Glohe quadrangle. — This area was surveyed and its mines and ore 
deposits studied in the autumn of 1901 by F. L. Ransome, assisted 
during part of the time by J. D. Irving. It lies to the southeast of 
the Bradshaw quadrangle and in a similar relation to the great Plateau 
region of northeastern Arizona. It includes the important mines of 
the Old Dominion and United Globe companies, together with many 
other deposits, of both copper and silver, which are mostly replace- 
ments of limestone associated with eruptive rocks. The report on 
this district was completed during the summer of 1902 and will shortly 
appear as Professional Paper No. L2. 
Clifton-Mort nci quadrangle. — This area lies still farther southeast, 
near the borders of New Mexico and also not far from the southwest- 
ern edge of the great Plateau region. The three areas just mentioned 
thus give important data as to the remarkable change of structure 
from the horizontal attitude and comparatively undisturbed position 
of the strata in the plateau to 1 heir ex1 remely broken and complicated 
structure in the ranges of the Basin region. This area, which is of 
even greater economic importance than either of the other two, was 
studied by W. Lindgren, assisted by J. M. Boutwell. The field work 
was commenced in the autumn of 1901 and continued well on into the 
spring of 1902. The ore occurs mainly in limestone and associated 
eruptive rocks. Mr. Lindgren is now engaged in the preparation of 
his report, of which a brief summary is given on later pages. 
Bisbee mining district. — This district was studied in 1892 hy F. L. 
Ransome, assisted by J. Morgan Clements and A. B. Rock. The area 
lies in the extreme southern part of the Territory, near the Mexican 
boundary line. It has long been one of the most important copper 
producers of the Territory, and, as in the last-named district, mining 
has received a new impetus as the result of the recent impulse given 
to copper mining in general through the increased demand for the 
metal and its consequent rise in price. The ores occur in limestone 
near eruptive rocks, but without the contact phenomena that charac- 
terize the Clifton-Morenci deposits. They present remarkably clear 
evidence of secondary enrichment by descending solutions. Mr. Ran- 
some is at present engaged in preparing his report of the region, of 
which a brief statement is given in this bulletin. 
