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PACIFIC SCIENCE, Vol. XII, October, 1958 
Fig. 1 . Map showing the location of the Palau Islands in the western Pacific Ocean. 
Peleliu, Angaur, and Koror and much of 
Auluptagel are also high limestone ridges. 
The maximum elevation of the high limestone 
islands is 686 feet above sea level on Uruk- 
thapel. Slopes of these islands are generally 
steep or very steep though a few have small 
central depressions with mild relief. 
The volcanic islands, so named because of 
the underlying basement rock, are generally 
hilly to rolling with local relief commonly 
measurable in tens of feet. Slopes and ridge 
crests are rounded and subdued. Babelthuap 
has three prominent ridges running roughly 
parallel to the long north-south axis of the 
island. The highest elevation in the Palau 
Islands is that of 794 feet above sea level on 
one of the ridges in northwestern Babelthuap. 
The volcanic islands (Babelthuap, Arakabe- 
san, Malakal, Auluptagel, and Koror) are all 
closely grouped in the northern part of the 
chain. As mentioned earlier, Auluptagel and 
Koror are partly volcanic rock and partly 
limestone. 
Soil Parent Materials 
The variety of rocks from which soils have 
been derived is relatively small in the Palaus. 
The platform and high limestone islands con- 
sist of former coral reefs. The present surface 
of the high limestone islands is largely a mass 
of rubble of assorted sizes. Much of the land 
surface of the platform islands also consists 
