Soils of Palau — VESSEL AND SIMONSON 
291 
TABLE 1 
Exchangeable Calcium and Magnesium, pH, Exchange Capacity, Base Saturation, 
and Organic Matter in Three Latosol Profiles 
HORIZON 
DEPTH 
pH 
CATION 
EXCH. 
CAPACITY 
EXCHANGE- 
ABLE 
CALCIUM 
EXCHANGE- 
ABLE 
MAGNESIUM 
BASE 
SATURA- 
TION 
ORGANIC 
MATTER 
Inches 
m.e./100 g 
m.e./100 g 
m.e./100 g 
Per cent 
Per cent 
LATOSOL 
FROM BRECCIA* 
Al 
0-12 
5.6 
22.4 
8.3 
1.8 
45 
5.20 
B21 
12-26 
5.6 
15.3 
6.2 
0.8 
46 
2.35 
B22 
26-33 
5.8 
16.7 
6.6 
0.7 
44 
2.45 
B23 
33-39 
6.2 
20.3 
7.8 
0.5 
41 
1.44 
Cll 
39-60 
6.2 
13.9 
7.6 
0.5 
58 
0.50 
C12 
60-88 
6.6 
15.8 
8.8 
0.7 
60 
0.37 
BAUXITIC 
LATOSOL 
FROM BRECCIA* 
Al 
0-6 
5.0 
12.0 
0.4 
0.4 
6 
4.79 
B2 
6-18 
5.0 
8.3 
0.1 
0.4 
7 
2.38 
Cl 
18-28 
5.2 
10.1 
0.3 
0.5 
4 
0.98 
C2 
28-34 
5.2 
10.2 
0.3 
0.6 
10 
0.85 
C3 
34-76 
5.2 
14.3 
0.2 
0.3 
4 
0.64 
LATOSOL 
FROM TUFFS f 
A 
0-3 
36.7 
7.1 
5.7 
37 
B 
3-18 
31.0 
12.2 
2.8 
50 
Cl 
18-42 
31.5 
19.6 
1.8 
69 
C2 
42-60 
30.7 
17.6 
1.7 
64 
* Analyses through courtesy of Dr. G. D. Sherman, Chairman, Department of Soils and Agricultural Chemistry, Univer- 
sity of Hawaii. 
f Analyses by E. M. Roller, Soil Survey Laboratories, Soil Conservation Service, U. S. Dept, of Agriculture. 
in determining composition of samples given 
in Table 2. The quantities of gibbsite and of 
silicate clay minerals were estimated by Gold- 
ich from differential thermal analyses and the 
chemical analyses. Hematite and other min- 
erals were obtained by difference. 
6. Comparisons of Soils in Palau Islands, 
Hawaii, and Puerto Rico 
The Latosols in the Palaus have low de- 
grees of horizonation, diffuse horizon bound- 
aries, and common to numerous pinholes in 
the profile. Morphologically, they are com- 
parable to Latosols observed by Simonson in 
Hawaii, Puerto Rico, Ceylon, and Brazil. 
There are differences, however, among the 
Latosols in the Palaus as there are elsewhere. 
The Latosols low or lacking in concretions 
seem to be much less strongly weathered than 
are the bauxitic Latosols high in concretions. 
This inference is based on differences in 
morphology and on laboratory data given in 
Tables 1 and 2. 
The Latosols low or lacking in concretions 
have A horizons that are easily recognized be- 
cause they are darker and more friable than 
the B and C horizons. The B horizons are set 
apart because they are more plastic and less 
friable than the C horizons. Differences in 
plasticity are slight as indicated by dominant 
ranges in plastic index values (Casagrande, 
1932) of 6 to 9 for the A horizons, 21 to 31 for 
