292 
PACIFIC SCIENCE, VoL XII, October, 1958 
TABLE 2 
Composition of Layers from a Deep Section through a Bauxitic Latosol 
from Breccia Near Ngardmau, Babelthuap* 
DEPTH 
SiQ 2 
A1 2 0 3 
Fe 2 Q 3 
TiQ 2 
LOSS ON 
IGNI- 
TION 
GIBBSITE 
SILICATE 
CLAY 
MINERALS 
HEMATITE 
AND OTHER 
MINERALS 
Inches 
Per cent 
Per cent 
Per cent 
Per cent 
Per cent 
Per cent 
Per cent 
Per cent 
0-20 
0.98 
44.12 
25.55 
1.38 
26.14 
66 
2 
32 
20-28 
1.64 
34.83 
37.56 
1.68 
21.76 
51 
4 
45 
28-120 
7.63 
37.33 
29.85 
1.70 
21.22 
47 
17 
36 
120-180 
19.40 
35.21 
24.62 
1.42 
18.75 
29 
42 
29 
* Sampled by S. S. Goldich; hole 17, Taihei Area. Chemical analysis by Marie L. Lindberg, U. S. Geological Survey. 
the B horizons, and 6 to 18 for the C horizons. 
The Ci horizon of the Latosol profile de- 
scribed on Arakabesan has a plastic index of 
31, which is in the common range for B 
horizons. 
Morphologically, the dominant Latosols in 
the Palaus are like the Humic Latosols in 
Hawaii, described by Cline (Cline etal., 1939). 
The profiles from breccias and tuffs are much 
like the Humic Latosols in the character, se- 
quence, and thickness of horizons. Both pro- 
files in the Palaus, however, are lower in or- 
ganic matter than Humic Latosols in Hawaii, 
being more like the Low Humic Latosols in 
this feature. The profile from tuffs has ex- 
change capacities ranging from 31 to 37 
milliequivalents per 100 grams which falls 
within the common range of 30 to 40 milli- 
equivalents for Humic Latosols in Hawaii. On 
the other hand, the profile from breccia has 
exchange capacities ranging from 14 to 22 
milliequivalents per 100 grams which parallels 
the range of 15 to 30 milliequivalents for Low 
Humic Latosols. Ratios of exchangeable cal- 
cium to magnesium are much higher in the 
two profiles from the Palaus than they are in 
the Humic Latosols or Low Humic Latosols 
of Hawaii. All in all, the less weathered 
Latosols of the Palau Islands seem marginal 
between the Low Humic Latosol and Humic 
Latosol groups recognized in the Hawaiian 
Islands. 
The Latosols in the Palaus also resemble 
those in Hawaii in low plasticity and sticki- 
ness despite high clay contents. Some Low 
Humic Latosols in Hawaii are 80 per cent 
clay but feel as though they were silty clay 
loams when worked between the fingers. 
Field textures of Latosols in the Palaus seem 
marginal between silty clay loam and silt loam 
in the A i horizons and between silty clay and 
silty clay loam in the B horizons. There is 
little reason to believe that the Latosols of the 
Palaus are lower in clay than those in Hawaii. 
Latosols, though high in clay, commonly 
have low shrinkage values upon drying and 
show little or no expansion upon wetting. 
This behavior has been correlated with high 
liquid limit and low plastic index values. The 
liquid limits for Latosols in the Palau Islands 
mostly range from 56 to 82. Lower values were 
found in the bauxitic Latosol, which had 
liquid limits of 39 in the Ai and 45 in the 
lower C horizons. The plastic index ranges 
from 6 to 31, as was indicated in an earlier 
paragraph. Within the continental United 
States liquid limit and plastic index values of 
similar magnitude are found in the Davidson 
series (Fruhauf, 1946) and similar soils, which 
have been classified in the Reddish-Brown 
Lateritic group (Simonson, 1949). Although 
similar to Latosols in a number of ways, the 
Davidson profile has a much more distinct 
and far less friable B horizon. Field descrip- 
tions of the Latosols in the Palaus as well as 
the liquid limit and plastic index values sug- 
