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PACIFIC SCIENCE, Vol. XII, October, 1958 
drainage. Total area of this association is 
slightly more than 4 square miles. 
The dominant poorly-drained soils show 
the effects of a water table at or near the sur- 
face an important part of each year. A typical 
profile has a surface layer of brown (7.5YR 
4/4) silty clay loam about 9 inches thick un- 
derlain by gray (5Y 5/1) or olive-gray (5Y 
4/2) silty clay mottled with brownish yellow 
(10YR 6/8). Somewhere between 234 and 4 
feet this gives way to dark-gray, nearly 
impermeable clay free of mottles. 
Well-drained soils in this association are 
commonly of similar texture but have brown 
surface layers grading downward into red, 
reddish brown, yellowish red, or yellowish 
brown. Mottled patterns and colors of 5Y hue 
are lacking in the well-drained soils. Soils 
with drainage intermediate between the well- 
drained and poorly drained ones are also 
intermediate in their morphology. 
The Alluvial Soils are adapted to most 
crops that can be grown in the Palau Islands. 
In spite of the suitability of the soils for 
cultivation, however, very little of this associ- 
ation was being tilled in 1948. Most areas 
were idle, generally supporting tall coarse 
grasses which were replaced locally by poor 
forest. Taro was being grown on some 
patches of wet Alluvial Soils near villages. 
Other crops that seem to grow well on the 
Alluvial Soils are cassava, bananas, coconuts, 
and pineapples. 
3. Muck and Peat 
These organic soils are of major importance 
to present food production, despite their 
small total area. They occur as scattered indi- 
vidual bodies, mostly along the northeast 
coast of Babelthuap and on the islands of 
Angaur and Peleliu. Some bodies are too 
small to be shown in Figure 2. The total area 
of organic soils is slightly less than 3 square 
miles. 
Muck consists of black, neutral to mildly 
alkaline, highly decomposed organic matter 
mixed with some mineral matter. Thickness 
of the muck commonly ranges from 2 to 334 
feet although it may be slightly less than 1 
foot thick in places. The muck is generally 
underlain by gray silt, gray clay, or coral sand. 
On Angaur, all of the muck is underlain by 
phosphate ore in the form of pellets. Approx- 
imately 90 per cent of the total area of organic 
soils consists of muck. 
Peat is less decayed than muck and is also 
commonly lower in mineral matter. Plant 
structures in the peat can be readily identified. 
The deposits range from 1 to 334 feet in thick- 
ness over limestone or phosphate ore. The 
areas of peat are approximately 10 per cent of 
the total of Organic Soils. 
The Organic Soils are especially valuable in 
the Palau Islands because of their suitability 
for taro production. They produce high yields 
of the crop, which is a major item in the diet 
of the people. 
Lithosols , Stony Land , Rock Land , and Man- 
grove Swamp 
This group comprises one soil association 
and three miscellaneous land types. Col- 
lectively, the group has a total area of 49 
square miles, ranking second to the Latosols 
from Breccias. Despite their large extent, 
however, the Lithosols and miscellaneous 
land types have little usefulness to agriculture. 
1. Lithosols from Volcanic Rocks 
The main features of this association are 
the shallowness of soils, common occurrence 
of rock outcrops, and steep topography. Usu- 
ally 6 to 15 inches deep over hard rock, the 
soil is dark, slightly acid, and commonly 
marked by a faint and thin Ai horizon. Rock 
fragments are common on the surface and 
throughout the profile. Massive rock out- 
crops occur along ridge crests. The associa- 
tion has steep to hilly topography and is cov- 
ered by forest or savanna. The steepest areas 
are mostly in forest, whereas the remainder is 
covered by coarse grasses and low shrubs 
with scattered pandanus trees. Restricted to 
Babelthuap and small nearby islands not 
