X, A, 5 Pratt: Reconnaissance in Caramoan Peninsula 315 



schists, succeeded the period of sedimentation. This dynamism 

 affected most strongly the central and western parts of the 

 peninsula and left the sedimentaries at the eastern end unmeta- 

 morphosed. The rocks converted into schist have not lost their 

 original bedded structure. The igneous basement upon which 

 the sediments lie has not been rendered thoroughly schistose, 

 but this is probably because the igneous rocks were less re- 

 sponsive to dynamic action than the bedded rocks. Just what 

 form the dynamism assumed is undetermined. Adams " con- 

 cluded that Caramoan Peninsula had suffered a severe thrust 

 from the Pacific (northern) side and perhaps this is the true 

 explanation. Certainly the strata have been forced into folds 

 along a predominatingly west-northwest line, and over compara- 

 tively extensive areas the sedimentary and metamorphic rocks 

 are inclined at steep angles southward. 



Subsequent to the period of metamorphism quartz was intro- 

 duced along bedding planes and fractures, forming quartz lenses 

 in the schists and concretions of chert locally in the unmetamor- 

 phosed limestones. Perhaps the observed pyrite lenses and the 

 veinlets of pyrite and chalcopyrite are related to this activity 

 also. The volcanism which produced the tuffs, flows, and ag- 

 glomerates of andesite along the northern coast began toward the 

 end of the period of sedimentation, but belongs essentially to a 

 later time. Finally came the extrusion, which built up Mount 

 Isarog and joined Caramoan to the mainland of southeastern 

 Luzon. 



During recent times erosion and the submergence evidenced 

 by the drowned appearance of the north coast have been the 

 principal factors in modifying the contour of Caramoan Penin- 

 sula. The recent submergence has permitted the Pacific to 

 advance on the land, drowning the rivers and submerging, except 

 for the highest points which remain as islands, a considerable 

 area that formerly extended to the north from Caramoan Penin- 

 sula. At present the submergence is no longer in progress, but 

 to judge from slightly raised beaches along the north coast, 

 elevation has once more begun. 



ECONOMIC GEOLOGY 



GENERAL 



Caramoan Peninsula is important principally on account of 

 its forest resources. Neither agriculture nor mineral industries 

 have become prominent on the peninsula proper, although hemp 



" This Journal, Sec. A (1911), 6, 469. 



