4 ART. 12. — B. KOTü : 



village of Sam-deung ^\ About thirty kilometers upstream, it re- 

 ceives a small affluent, the U-gang -\ which comes from the south. 

 The upper course of this branch lies in the drainage area which 

 constitutes the mining district under consideration. A map (see 

 PI. IV.) of the mining region clearly shows the relation between 

 the geologic structure and the drainage system. Rivulets take a 

 long equatorial course in somewhat widened dells, turning suddenly 

 in the meridional direction in a short defile. Such is the small 

 stream, the Ugang, which flows along the south of the Hol-gol 

 mine. It turns abruptly northward at Tol-hogai "'\ and again to the 

 east along S'ôk-tari ^^ in order to join the Sin-gyoi-gang already 

 mentioned. Generally speaking, therefore, the courses of the brooks 

 in the neighborhood of the mine are equatorial and meridional, 

 draining the waters of the hilly interior lying about 300 m above 

 sea level. 



The gold mine of Hol-gol is located on the north flank of a 

 range of hills running W. N. W. to E. 8. E., being separated on 

 the south from the already-mentioned Oii-jin-san by the valley of 

 Morai-chhi ^\ which takes a course nearly parallel to the hill range. 

 The mining office is on the south side of the 3Iorai-chhi valley. 

 On the west and north-west of the mine, the ground rises 

 showing topographical features somewliat resembling those of a 

 terrace, the elevation being the remnant of a tilted crustal block 

 dislocated meridionally, in the process of which the ground on 

 the eastern side was thrown down. The edge of the break lies 

 west of, and parallel to, the Hol-gol valley, which consequently is 

 itself a tectonic depression. See Pi. IV. 



On the east the ground again rises into a steep, meridional 



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