GEOLOGY: W. M. DAVIS 
199 
and submerged barrier reefs," according to the second clause, may be deter- 
mined for certain islands by the abundant off-shore soundings. Thus in the 
case of Palawan, its embayed western coast does not descend rapidly to great 
depths, but is fronted by a well defined submarine platform, 20 or 30 miles 
wide, along the seaward edge of which a discontinuous rim rises towards but 
not to the surface ; the rim can be most reasonably explained as an incomplete 
upgrowth from a barrier reef of an earlier generation on the outer margin of a 
broad lagoon. It is not possible, in our present ignorance of the geology of 
Palawan, to determine whether the drowned barrier reef was formed by up- 
growth during slow and long continued subsidence, or by outgrowth during a 
long-enduring still-stand of the island; but in either case, the great breadth of 
the lagoon plain appears to be the product of a long lasting process, and thus 
contrasts strongly with the new fringing reefs of the Malampaya district, 
which are so narrow as to be inconspicuous on charts of the largest scale. 
Evidently, therefore, the rapid submergence by which the barrier reef of 
Palawan was drowned must be of recent date. 
Similar conclusions may be derived from other parts of the Philippines, 
where embayed shore lines, relatively narrow fringing reefs, and well defined 
submarine platforms are frequently found, although no islands are so striking 
in these respects as Palawan. The platforms cannot be reasonably ascribed 
to marine abrasion during a higher stand of the islands or a lower stand of 
the ocean, for the island shores are not clift; and the submergence of the plat- 
forms cannot be accounted for by a rise of ocean level, which must everywhere 
be of the same date, amount and rate, for the platforms vary in depth, and 
the new fringing reefs vary in breadth. The depth of the Palawan platform 
for example, increases from 25 or 30 fathoms at its southwestern end to 55 or 
60 fathoms near its middle, and then decreases again toward the northeastern 
end ; and the fringing reef, which is hardly chartable near the mid-length of the 
island where the platform is deep, has a width of 1 or 2 miles at the south- 
western end of the island where the platform is relatively shallow. 
On the other hand, the northeastern coast of Samar, on the opposite side of 
the archipelago from Palawan, has a moderately sinuous shore line with delta 
flats that diminish the initial size of its bays, and fringing reefs that reach 
forward a mile or so from its points; here the latest submergence cannot be so 
recent as that of Palawan. But instead of being benched by a submerged 
platform, the sea bottom off shore from Samar sinks rapidly to a great depth. 
Moreover, there are long stretches of the coast of Luzon which are neither 
embayed by arms of the sea, nor enclosed by barrier reefs, nor fronted by 
submarine platforms: Luzon, unlike many other of the Philippines, has a con- 
siderable extent of coastal lowlands, as if the growth of fringing reefs, or the 
outwash of detritus, or the emergence of the former sea border had increased 
its low littoral area. Again, Cebu and Negros, which occupy a somewhat 
central position in the archipelago, are described by Becker as terraced with 
elevated reefs up to altitudes of 2000 feet or more. The diverse shore features 
