402 FERGUSON. 



THE AROEOY DISTEICT. 

 LOCATION AND TOPOGRAPHY. 



The Aroroy mining district is situated near the northwestern corner 

 oJ! the island in the group of hills to the east of Port Barrera, which is 

 a deep bay extending southward for a distance of about 13 kilometers. 

 Anyone entering this bay must be struck by the extremely different topo- 

 graphy exhibited on either side. To the westward are series of nearly 

 horizontal sedimentaries, limestone, conglomerate, and shale. The lime- 

 stone outcrops form a regular series of terraces which can be followed 

 without a break for great distances. Toward the southern part of the 

 bay erosion has broken these terraces into a number of small mesas. On 

 the other hand, the country on the Aroroy side is more irregular and the 

 hills present smooth, rounded outlines without any trace of terracing. 



Mount Vil-lon, lying just outside the area mapped, is the highest 

 mountain in the district, having an elevation of about 400 meters. It 

 differs from the other hills in having a northeasterly trend, and breaks 

 off precipitously at Monument Rock, near the Guinobatan Elver. The 

 majority of the mineral veins outcropping in the district are found in 

 the three hills. Mounts Aroroy, Bagadilla, and Kalakbao. "While the 

 summits of these three hills lie in a north and south line, the individuals 

 show a pronounced northwesterly trend, due to the superior resistance to 

 erosion offered by the quartz veins. Mount Aroroy, or Kanatanatawan, 

 (elevation 255 meters) lies farthest to the north and is separated from 

 the highest of the three hills, Mount Bagadilla (elevation 350 meters), 

 by Bangon Creek, which here flows through a deep canon. Mount Baga- 

 dilla, on its western side, sends out several northwesterly spurs marking 

 the situation of different quartz veins. The gorge of the Gruinobatan 

 River separates Mount Bagadilla from the southern hill. Mount Kalakbao, 

 which has an elevation of 220 meters. 



A long stretch of irregular country broken by a series of small hills 

 extends to the south and west from Mount Kalakbao until the Lanang 

 River is reached. (Plate I, fig. 2.) This river cuts a complicated 

 channel through a range of hills of over 200 meters elevation, and follows 

 a northwesterly course. Mount Cogran lies just to the northeast of this 

 range, its height being due to the resistance of the quartz veins which 

 outcrop here. 



Tlie area is drained by several permanent streams, all of which (the 

 Buyuan River lying outside the area proper) drain northwestward into 

 Port Barrera. Three principal streams drain the area : The Guinobatan 

 River, Panique Creek, and the Lanang River. The northern branch 

 of the Guinobatan, Bangon Creek, flows in a deep gorge between Mount 

 Aroroy and Mount Bagadilla; while its direction is northwesterly it 

 does not follow the strike of the quartz veins, but cuts obliquely across 



