viii, a, 4 Smith: Fossil Invertebrate Fauna 241 



is seen in sections along the Bued and Agno Rivers. This is 

 basal. Other great deposits of conglomerate are encountered 

 farther north at an elevation of nearly 2,000 meters. In some 

 localities this formation is fairly rich in fossils, as in Trinidad 

 Gap, Benguet. 



Probably the best geological sections in the Archipelago are 

 on Panay. These show great thicknesses of conglomerate and 

 sandstone. The conglomerates here are bedded and conformable 

 to the strata above and below. 



Tuffs. — There is a great deposit of pyroclastic material, with 

 intercalated beds of sand and silt extending over a considerable 

 area of southwestern Luzon, particularly over Cavite and Ba- 

 tangas Provinces and the country adjacent to Manila. A great 

 deal of this material probably came from Taal Volcano, but 

 also from other vents, many of which in a former period existed 

 throughout this region. When first quarried, the material is 

 soft, but gradually hardens on exposure. It is buff, to gray in 

 color. It was extensively used in the Spanish regime, and is 

 still quarried to a less extent for building purposes. This stone 

 is known in the trade as "Guadalupe stone." Fragments of 

 pumice, black hornblendes, fragments of feldspar, etc. give the 

 rock a very heterogeneous composition and coarse' texture. The 

 maximum thickness of the deposit is probably more than 100 

 meters. The best exposures are to be seen in several quarries 

 along the banks of the Pasig River. This deposit has yielded 

 a few fossils. 



Adams, 10 who has studied this tuff more closely perhaps than 

 any one else, says of these fossils : 



Occasionally a log of wood has been encountered in drilling, and plant 

 remains, fish teeth (fig. 3), and one mammalian tooth (fig. 4) have been 

 found in the beds. The presence of the plant remains has been recorded 

 by many observers. The greatest depth at which a log of wood has been 

 found is in the Alabang wells southeast of Manila where one was cut by 

 the drill at a depth of between 130 and 132 meters. The mammalian 

 tooth was obtained from the Pasig well at a depth somewhere between 

 81 and 85 meters. [Figs. 3 and 4 refer to Adams's article.] 



"This Journal, Sec. A (1910), 5, 73. 



