MINERAL RESOURCES OF AROROY DISTRICT. 411 



and drowned in a recent depression. Hence it seems probable that the 

 low land lying south of the head of this bay represents the lower portion 

 of the shale, and it is here that the coal measure should be looked for. 

 Above the shale is an unconformity marked by 8 or 10 meters of conglo- 

 merate which here contains pebbles of augite andesite and vein qiiartz, 

 evidently derived from the Aroroy district and hence an important factor 

 in determining the age of the veins. Above the conglomerate are several 

 beds of limestone belonging to the Upper Miocene or perhaps Pliocene. 

 Doctor Smith has furnished the following notes relative to the fossils 

 collected in these sedimentaries : 



Mr. Ferguson and I visited this locality in August, 1909, and, collected a suite 

 of fossils containing: 



Pleurotoma gendinganensis Mart. lianella spinosa Lam., living. 

 Pleurotoma carinata Gray var. uood- Ranella nobilis Reeve, living. 



wardi Mart. Phos acuminatus Mart. 



Conus sulcatus Reeve, living. Cassis pila Reeve, living. 



Conns sinensis Sow., living. " Flabellum sp. 



Odontocyathvs sp. nov. Dentalium sp., living. 



Nassa verbeeki Mart. Capulus sp. 



These species' are nearly all represented by living forms in Philippine waters 

 to-day, so that the beds which enclose them (and they show very little consolida- 

 tion) are very recent. I would assign them to the Pliocene. 



Later alluvial deposits. — Deposits of post-Tertiary origin may be 

 divided into three classes : Deposits left by former streams, by the 

 present streams, and by mangrove swamps. 



The old course of the Lanang Eiver northeast of the range of andesite 

 hills in the southern part of the area is marked by a broad belt of 

 stream gi-avels. The conditions whicli probably led to this curious 

 change in the course of this river, causing it to adopt a longer one and 

 twice to cut through the range of .andesite hills, have been discussed 

 at length in my previous paper ^'■' and need not be repeated here. A 

 small area of gravels likewise occurs north of this point, marking an older 

 river course of uncertain direction. 



The Lanang Eiver has developed a small fioodplain between its two 

 gorges. Here a curious abandoned meander also occurs, apparently the 

 incised relic of an earlier course. The gravels here formed the dredging 

 grotmd operated for a short time by the Lanang Dredging Company. 

 The Luya, a tributary of the Lanang, drains the region in which the Mount 

 Cogran veins outcrop, but I have not been able to learn what were the 

 results of testing in this ground. The lower part of the Lanang Eiver 

 has developed a typical flood-plain, the sides of which slope gently away 

 from the river. This is clearly shown on the map by the courses of the 

 two small streams flowing parallel to it. The one on- the south empties 



" This Journal, Sec. A ( 1909 ) , 4, 6-7. 



