Soils of Palau — Vessel and Simonson 
structure, and consistence but not in color. 
The differences may reflect marked banding in 
the original parent materials or disturbance of 
some kind, possibly by man. Disturbance 
seems probable in view of widespread occur- 
rence of pottery fragments at some depth in 
Latosol profiles in the Palau Islands. Labora- 
tory data also suggest the possibility that the 
present B 2 3 horizon may at one time have 
been an A horizon, later covered by soil ma- 
terial of similar composition moved down- 
slope from higher uplands. 
The slope gradient at the profile site on 
Arakabesan falls near the lower end of the 
dominant range for the association as a whole. 
Consequently, the solum is thicker than aver- 
age. It is estimated that 10 per cent of the 
Latosols in this association have deeper solums 
and that 60 per cent have slightly shallower 
solums, i.e., between 2 and 3 feet. The re- 
maining 30 per cent have solum thicknesses 
falling between 1 and 2 feet. Regardless of 
variations in solum thickness the regolith is 
deep for all Latosols in this association, com- 
monly ranging from 10 to 60 feet. Occasion- 
ally, thickness of the regolith may exceed 60 
feet to the underlying basaltic or andesitic 
volcanic Breccias. 
Concretionary or bauxitic Latosols, Litho- 
sols and lithosolic soils, and Alluvial Soils 
comprise from 10 to 15 per cent of the associ- 
ation. Proportions of these three minor 
groups are approximately equal. The concre- 
tionary Latosols are similar to the dominant 
soils in the association of bauxitic Latosols 
from Breccias. In contrast to the Latosols, 
the Lithosols and lithosolic soils are formed 
in shallow regoliths, usually marked by rock 
outcrops. The Alluvial Soils occupy toe slopes 
and narrow valleys and are similar to those 
described in the subsection on Regosols, 
Alluvial Soils, and Organic Soils. 
2. Bauxitic Latosols from Breccias (Babel - 
thuap Association) 
The dominant soils of this association are 
the most strongly weathered Latosols of the 
287 
islands. Striking features of these soils are the 
large numbers of concretions on the surface 
and in the profile. Approximately half of the 
total area of this association consists of red- 
dish, bauxitic Latosols. Most of the remainder 
consists of Latosols that are low or lacking in 
concretions, but there are also minor propor- 
tions of Lithosols or lithosolic soils and of 
Alluvial Soils. Much less extensive than 
Latosols from Breccias, this association has a 
total of 19 square miles, all on Babelthuap. 
Major areas are in the west central part of the 
island, though two small ones are near the 
south coast. 
Topography is dominantly hilly. Slopes 
may be slightly steeper, on the average, than 
they are in the association of Latosols from 
Breccias. Local relief is commonly measurable 
in many tens of feet. 
A profile description representative of the 
dominant bauxitic Latosol of the association 
is as follows: 
(a) Setting . The profile was described and 
sampled in a former strip mine used for the 
extraction of bauxitic ore, approximately 
1,600 yards south of Ngardmau on Babel- 
thuap. The site has a slope of about 15 per 
cent to the east. Vegetation near the strip 
mine consists of coarse grasses and brush 
interspersed with almost pure stands of ferns 
( Gleichenia linearis). 
(b) Profile Description. 
Ai 0-6" Brown (7.5 YR 4/4) gravel- 
ly loam; moderate fine 
granular structure; soft, fri- 
able; brownish coarse and 
very coarse vesicular platy 
concretions common, few 
brown fine concretions; 
many very fine, fine, and 
medium roots; few small 
worm casts; very strongly 
acid. 
B 2 6-18" Red (2.5YR 4/8) silty 
clay; compound structure 
of moderate coarse sub- 
angular blocks breaking 
