Substantially enriched geological data have accumulated since the Geology and Oil Possibilities of the Philippines by Corby, et al., 1951 was published. Most of them are the results of intensive regional mapping done by the Geological Survey and Petroleum Divisions of the Philippine Bureau of Mines; some basin areas were worked out by private oil companies. This paper is an attempt to fill the need to modify some of the earlier geologic interpretations and existing views regarding the tectonic evolution of the Archipelago in view of the fact that since the early part of 1960 numerous intrusive and sedimentary rocks considered as pre-Tertiary basement have turned out to be either Paleogene or Miocene in age.