MANILLA. 301 



rocks which contain them, were presented to the Expedition by 

 Sefiors Araria and Roxas of Manilla. These will claim particular 

 attention in the Geological Report, to which the reader is referred 

 for information. 



So far as our information and observations went, the whole of the 

 Philippine Islands are of similar geological formation. In some of 

 the islands the volcanic rock prevails, while in others coal and the 

 metalliferous deposits predominate. On some of them the coal-beds 

 form part of the cliffs along the shore; on others, copper is found 

 in a chlorite and talcose state. The latter is more particularly the 

 case with Luzon, and the same formation extends to Mindoro. 

 Much iron occurs on the mountains. Thus, among the Tagala 

 natives, who are yet unsubdued by the Spaniards, and who inhabit 

 these mountains, it is found by them of so pure a quality that it is 

 manufactured into swords and cleavers. These are, occasionally, 

 obtained by the Spaniards in their excursions into the interior against 

 these bands. 



The country around Manilla is composed of tufa of a light gray 

 colour, which being soft and easily worked, is employed as the 

 common building material in the city. It contains, sometimes, scoria 

 and pumice, in pieces of various sizes, besides, occasionally, impres- 

 sions of plants, with petrified woods. These are confined to recent 

 species, and include palms, &c. 



This tufa forms one of the remarkable features of the volcanoes of 

 the Philippine Islands, showing a strong contrast between them and 

 those of the Pacific isles, which have ejected little else than lava and 

 scoria. 



Few portions of the globe seem to be so much the seat of internal 

 fires, or to exhibit the effects of volcanic action so strongly as the 

 Philippines. During our visit, it was not known that any of the 

 volcanoes were in action ; but many of them were smoking, parti- 

 cularly that in the district of Albay, called Isaroc. Its latest erup- 

 tion was in the year 1839 ; but this did little damage compared with 

 that of 1814, which covered several villages, and the country for a 

 great distance around, with ashes. This mountain is situated to the 

 southeast of Manilla one hundred and fifty miles, and is said to be a 

 perfect cone, with a crater at its apex. 



It does not appear that the islands are much affected by earth- 

 quakes, although some have occasionally occurred that have done 

 damage to the churches at Manilla. 



VOL. V. 70 



