Bolinao, Mabini, Agno, Hundred Islands, Pangasinan
Pliocene - Pleistocene
Coralline reefal limestone at Mabini, Bolinao, Agno and the Hundred Islands in Pangasinan were previously included with the Sta. Cruz Formation. However, Karig and others (1986) argue that these limestones were formed in a distinctly different environment and therefore represent another formation. They also cite a proprietary report of the Philippine Bureau of Energy Development that describes horizontal Early Pliocene limestone capping Middle to Late Miocene sedimentary sequence in Burgos. Recent samples of limestones in the Hundred Islands and in Bolinao also yielded Pliocene-Pleistocene fossils. At Mabini, Pangasinan, BEICIP (1976) reports that the limestone, with an estimated thickness of 250 m, yielded fossils which were dated Early Pliocene (N19). In the absence of more detailed studies of these limestones, they are tentatively designated as Bolinao Limestone.