the mainland by solid earth in the early or Middle Tertiary. For a
long geologic time the land was low and swampy. At the end of the
Eocene a great upheaval occurred; there were foldings and crumplings,
igneous rock was thrust into the distorted mass, and the islands
were considerably elevated above the sea. During the latter part of
the Tertiary period the lands seem to have subsided and to have been
separated from the mainland.

About the close of the subsidence eruptions began which are continued
to the present by such volcanoes as Taal and Mayon in Luzon and Apo
in Mindanao. No further subsidence appears to have occurred after
the close of the Tertiary, though the gradual elevation beginning
then had many lapses, as is evidenced by the numerous sea beaches
often seen one above the other in horizontal tiers. The elevation
continues to-day in an almost invisible way. The Islands have been
greatly enlarged during the elevation by the constant building of
coral around the submerged shores.

It is believed that man had appeared in the great Malay Archipelago
before this elevation began. It is thought by some that he was in
the Philippines in the later Tertiary, but there are no data as yet
throwing light on this question.

To-day the Archipelago lies like a large net in the natural pathway
of people fleeing themselves from the supposed birthplace of the
primitive Malayan stock, namely, from Java, Sumatra, and the adjacent
Malay Peninsula, or, more likely, the larger mainland. It spreads
over a large area, and is well fitted by its numerous islands --
some 3,100 -- and its innumerable bays and coastal pockets to catch
up and hold a primitive, seafaring people.