198 
GEOLOGY: W. M. DAVIS 
the coral-reef problem by reason of the great volume of carefully ascertained 
facts that they present. They are in various respects more detailed and more 
accurate than the Admiralty and Hydrographic Charts hitherto available. 
Many of the islands are thus shown to have more or less minutely embayed 
shore lines, indicative of the subrecent or recent submergence of an eroded 
land surface. This is particularly true of Palawan, the southwesternmost 
member of the group, which has a shore line of most intricate pattern where 
its western side is indented by Malampaya sound: there can be no question 
that the coastal features of this kind exhibited on Palawan and many other 
members of the Philippine group result from the recent partial submergence 
of an uneven land surface. 
According to Darwin's theory of coral reefs, in the form usually presented, 
shores of submergence should be fronted by barrier reefs; but the Malampaya 
district of Palawan is not so fronted; its reefs, where they occur, belong to the 
fringing class, and since Darwin's time fringing reefs have been associated 
with stationary or emerging shores. Barrier reefs are indeed exceptional 
in the Philippines, in spite of the repeated occurrence of embayed shore 
lines on many islands, and the question therefore arises whether the theory of 
upgrowing reefs on intermittently subsiding foundations is incorrect or in- 
complete. The object of this paper is to point out that the theory, as ordi- 
narily stated, is incomplete, and that the element needed to complete it is 
to be found in a seldom-quoted passage from Darwin's own writings, as follows: 
"If during the prolonged subsidence of a shore, coral-reefs grew for the first 
time on it, or if an old barrier-reef were destroyed and submerged, and new 
reefs became attached to the land, these would necessarily at first belong to 
the fringing class " (Coral Reefs, 124). 
This passage may be understood as meaning that the " prolonged subsi- 
dence" of an island might be too rapid to permit reef growth, until a pause 
allowed the establishment of a fringing reef; and also that the rapid subsi- 
dence of an island would destroy and submerge a barrier reef previously 
formed around it during slower subsidence, whereupon a fringing reef would 
be formed on the new shore line. Thus interpreted, the passage affords 
a satisfactory explanation of the frequent association of fringing reefs with 
shore lines of submergence in the Philippines and in certain other archipelagoes, 
even though such reefs may elsewhere be found on stationary shore lines or on 
shore lines of emergence. Fringing reefs thus formed may be described as 
"of a new generation:" they will evidently lie unconformably on the eroded 
rocks of the shore belt, and their unconformity, as well as the embayments 
of the shore line, will indicate their association with submergence. The con- 
tact of fringing reefs with the marine sediments that ordinarily characterize 
a non-embayed shore line of emergence would be essentially conformable. 
Whether the shores of the Philippines now for the first time have reefs 
formed upon them, according to the first clause in the above quotation from 
Darwin, or whether the existing fringes are the successors of "destroyed 
