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GEOLOGY AND ORE DEPOSITS OF THE COLLBRAN
In the Suan Mining Concession granitic intrusions have in-
1 Published with the permission of the Seoul Mining Company.
The general iocation of the Suan Mining District is in Central Korea (Fig. 1), about fifty-five miles east-south-east of the city of Pyeng Yang, Korea, approximately in latitude 38° 48′ north, and longitude 120° 20' east. The Suan Mining Concession held
FIG. 1. Map of Korea showing the general location of the Suan Mining Concession and the principal towns.
by the Seoul Mining Company (recently seized) covers an area of 40 by 60 Korean li, about 260 square miles. The camps are reached by government and company roads from Pyeng Yang. The generally rugged nature of the topography of the concession is indicated in Plate I., 4. The maximum difference of elevation on the concession is about 3,500 feet. The climate blends the characteristics of semi-tropical and north temperate conditions.
There is a rather heavy rainfall in the summer; while spring, autumn, and winter are comparable with those seasons in Ohio.
The general geologic features of the district are, briefly: a series of sedimentary rocks intruded by a granite batholith. The contact principally concerned (Fig. 2) is irregularly elliptical in outline with a periphery of about 21 miles, not taking into ac
FIG. 2. Suan granite and the Collbran contact. The position of placers, and prospects are indicated.
count the irregularities. The major axis of the ellipse extends in an east-south-east direction. The invasion of the granite has uplifted and pushed aside the overlying and surrounding rocks with tremendous force. Erosion has exposed the mass, showing a rim of the upturned edges of the sedimentary rocks around the granite. In the immediate vicinity of the granite the sediments