458 ADAMS. 



prison colony, the quarries were discontinued. The present plant oper- 

 ated by the city is on the northwest part of Talim Island at Subay, 

 where a crushing plant operated by steam and supplied with convenient 

 tracks, bins, and facilities for dumping into scows, is still in operation, but 

 shows the results of heavy usage. The stone at this quarry is of about the 

 same character as at Binangonan and Malagi. The better qualities are a 

 dense basalt, which has a conchoidal and splintery fracture and shows 

 2.57 per cent of wear. With it there is a variable vesicular and sometimes 

 scoriaceous variety showing 8.66 per cent of wear, and the gradation into 

 this quality is so irregular that in quarrying it is very difficult to separate 

 the two. Moreover, the processes of weathering have attacked the poorer 

 and softer stone and the quariy at Talim contains considerable dirt, so 

 that it is impossible to obtain continuously a clean, uniform crushed stone. 



A careful survey was made of the zone which embraces Talim Island 

 and Binangonan Peninsula. No better material was found occurring in 

 relations .suitable for quarrying. The zone is characterized by flows of 

 basaltic lava, varying from dense to vesicular and scoriaceous varieties, 

 and a large part is covered with volcanic agglon^erate and braccias, which 

 grade into tuffs. 



When the United States Army built the road between Los Banos and 

 Calamba, they opened a quarry near Los Bailos. The rock is a crystalline 

 andesite, usually quite dense in texture. There is a high face of rock 

 which rendered quarrying easy and a small crusher was installed which 

 gave a very satisfactory output. It shows 2.66 per cent of wear. Besides 

 using the stone on the road near Los Baiios, a considerable quantity of it 

 was transported to Fort McKinley and used in macadamizing the streets 

 of that post. The city of Manila has been deterred from using this quarry 

 because it was thought not to furnish the best quality of rock which could 

 be obtained, and that the transportation which would include that by land 

 to the shore of the lake and a long towage across to the mouth of the 

 Pasig Eiver would make the cost too high. 



The quarry at Sisiman, near Mariveles, was opened for the purpose of 

 supplying large stone for building the breakwater of Manila Harbor. 

 The city was induced to try crushed stone from this quarrj' for macadam, 

 and some streets were carefully prepared with it for the purpose of 

 making a practical test, but it was found rmsatisfactory since it is too 

 soft and wears rapidlj' iinder the action of wheels, disintegrating into 

 rock flour. Although the Cjualit}' of the stone was soon determined, some 

 additional attempts were made to use the screenings from it as a top 

 dressing over the Talim rock, "with a hope that it would serve as a binder. 

 As it has a very low cementing value, this experiment was not successful, 

 and the fact that the dressing consisted of fines containing a large amount 

 of rock flour rendered the streets muddy and necessitated the removal of 

 the dressing after the first heavy rains. 



