Up to the early 1970's it haf been assumed that the Philippines was a part of the mainland China. It was theorized that during the Pleistocene or Ice Age, the waters surrounding what is now the Philippines fell about 156 feet below the present levels. As a result, a vast area of land was exposed and became sort of land bridges to the mainland of Asia. In February, 1976, howeverm this theory of the "land bridges" to Asia was disputed by Dr. Fritjof Voss, a German scientist who studied the geology of the Philippines. According to Dr. Voss, the Philippines was never a part of the mainland of Asia but that it rose from the Bottom of the sea and "continues to rise as the thin Pacific crust moves below it."
As proof that the Philippines was never a part of the Asian mainland, Dr. Voss points to the fact when scientific studies were done in 1964-67 on the thickness of the earth's crust it was found out that the 35-kilometer thick crust underneath China does not extend to the Philippines. Hence, the latter could not have been a part or "land bridge" to the mainland Asia. On the other hand, the Philippines lies "along the great earth faults extending to deep undersea trenches" and so through violent earthquakes what is now the Philippines rose to the surface of the sea.