Soils of Palau — Vessel and Simonson 
and their approximate proportions. Patterns 
of occurrence of component soils also may 
be indicated. The component soils are de- 
scribed either by giving full morphological 
details for representative profiles together 
with data on topography and other features 
or by comparisons with soils that have been 
fully described. 
Miscellaneous land types are geographic 
units without classifiable soils or with low 
proportions of such soils. Examples in the 
Palau Islands are smooth stony land and 
limestone outcrop. Stray patches of classifia- 
ble soils occur in each of these units but 
comprise a negligible portion of the total area. 
The profile descriptions use horizon con- 
cepts and terminology as given in the Soil 
Survey Manual (Soil Survey Staff, 1951), un- 
less otherwise stated. The identification of 
field textures, i.e., apparent texture as de- 
termined by the fingers when the profile was 
being described, is given for individual hori- 
zons. Pinholes refer to pores that are 1 mm. 
or less in diameter, whereas wormholes are 
tubular channels about 3 mm. in diameter. 
Numbers of pinholes, wormholes, roots, stone 
fragments, and concretions are indicated by 
three relative classes, viz., few, common, and 
many. Concretions are roughly spherical, un- 
less otherwise noted, and their sizes are re- 
ferred to the same limits as granular structure 
(see Soil Survey Manual for these size limits). 
Each profile description is preceded by a 
brief statement on the geographic setting, 
and some are followed by comments not 
readily included in the description itself. 
Latosols and Latosolic Soils 
The Latosols are by far the most extensive 
soils in the Palau Islands, comprising some 
60 per cent of the total land area. As shown 
by the map in Figure 2, they are dominant on 
Babelthuap, Koror, Arakabesan, and Malakal, 
and form the north tip of Auluptagel. Despite 
their large acreage, however, they have lim- 
ited importance to local food production. 
285 
The Latosols of the Palaus are well drained, 
red to yellowish, friable, strongly acid, deep, 
and ferruginous or bauxitic soils derived 
mainly from volcanic rocks. The regoliths 
from volcanic rocks are weathered to great 
depths, but the soils do not seem to have 
correspondingly deep solums. The few lato- 
solic soils formed from sedimentary clays are 
less deeply weathered and have shallower 
solums than do those derived from volcanic 
rocks. 
These soils occur in moderately dissected 
uplands with a dendritic pattern of drainage- 
ways. Ridge crests are generally narrow, as are 
the valleys, and the intervening rounded 
slopes are relatively long. Local relief, i.e., 
differences in elevation within a unit area of 
approximately 160 acres (one-fourth square 
mile), are measurable in tens of feet, for the 
most part. In a few places local relief is meas- 
urable in one or two hundreds of feet, whereas 
in others it may be in feet. 
Three associations are dominated by Lato- 
sols formed from volcanic rocks, whereas a 
fourth consists of latosolic soils derived from 
clays. Brief descriptive names are used to 
identify the major group in each association. 
Such names are not being suggested as proper 
names for great soil groups but are intended 
for local identification of the soils. When the 
name of an association is used as a subsection 
heading, it is followed by another name or 
names in parentheses. These names in paren- 
theses identify the associations on the map of 
larger scale in the report on military geology 
of the islands (U. S. Department of the Army, 
1956). The information on the larger map has 
been generalized in preparing the map in 
Figure 2. 
1 . Latosols from Breccias (Palau Association) 
This association is dominated by Latosols 
that are red or reddish brown in the deeper 
profile. Colors are mainly of 2.5YR and 5YR 
hues 5 though a few soils are strong brown 
5 Munsell color notations. The application of this 
system of color notations to soils is discussed in the 
Soil Survey Manual (Soil Survey Staff, 1951). 
