X, A, 5 Pratt: Persistence of Philippine Coal Beds 297 



Americans was carried out on Batan Island, Albay Province. 

 The western half of this island was reserved by the United 

 States Army for the purposes of coal mining. On the eastern 

 end of the island the East Batan Coal Mining Company developed 

 a mine which yielded from 20,000 to 30,000 metric tons of coal 

 annually for several years. The work of the United States 

 Army demonstrated that faulting was a serious factor in the 

 nonpersistence of the coal beds on the reservation, while the 

 commercial mine at the other end of the island proved 

 the existence of a bed of considerable dimensions with no evi- 

 dence of faulting and but little indication of inconstant conditions 

 of deposition. 



Part of the exploration at the Army mine consisted of diamond- 

 drill work. The results of the drilling are very confusing and 

 difficult of interpretation. A large proportion of the different 

 holes drilled yielded no core because of the softness of the rocks 

 penetrated, and it is probable that the records of strata en- 

 countered are faulty on this account. One drill hole, according 

 to its record, penetrated 11 distinct beds of coal, yet it is im- 

 possible to correlate these beds with the results obtained in 

 adjacent holes. 



The mine workings yielded more definite information. An 

 opening on the Big Tree bed in the upper part of the coal-bearing 

 rocks advanced 14 meters in coal which lay about horizontal 

 and was 2.8 meters thick. For 10 meters the bed was perfectly 

 regular, but within the next 4 meters it decreased in thickness, 

 the floor rising abruptly in steps to about 30 centimeters. The 

 work was abandoned without any attempt to proceed beyond 

 the evidently faulted zone. Other openings of limited extent 

 encountered faults in much the same way. 



More important work was performed at New Number 5 mine, 

 in the base of the coal measures. A slope was driven through 

 rock to intersect two beds the presence of which was indicated 

 in adjacent drill holes. The beds appeared to be parallel to each 

 other and to dip at an angle of about 35°. The upper bed was 

 first encountered, and the slope was continued as a drift along 

 the strike of the bed for a distance of 60 meters. Throughout 

 this distance the bed was irregular and showed considerable 

 evidence of squeezing; at the end of the drift the coal was lost 

 along a fault. A horizontal crosscut was driven to the lower 

 bed through the intervening rock strata, a distance of about 

 10 meters. A drift on the strike of the lower bed from the end 

 of this crosscut, parallel to the drift on the upper bed and at 

 approximately the same level, advanced 50 meters to a fault. 



