Soils of Palau — VESSEL AND SIMONSON 
289 
Latosols formed from volcanic Breccias but 
lacking large numbers of concretions in the 
profile. These soils are identical with the 
dominant ones in the association of Latosols 
from Breccias, described earlier. Some do have 
more concretions in the surface layer than 
typical, thus being intermediate in character 
between the bauxitic and nonbauxitic Latosols. 
Lithosols or lithosolic soils and Alluvial 
Soils comprise 10 per cent or less of the as- 
sociation. The nature and distribution of these 
minor soils is similar in the two associations 
of Latosols from volcanic Breccias. 
3. Latosols from Tuffs (Ngardok Associa- 
tion) 
Although derived from different parent ma- 
terials, the dominant soils of this association 
closely resemble the Latosols formed from 
volcanic Breccias, especially those low in 
concretions. On the whole, the soils from 
tuffs have thinner solums and slightly lower 
permeability. They have fewer concretions in 
the profile and seem to be less weathered than 
the bauxitic Latosols from Breccias. Minor 
components of the association are Alluvial 
Soils and Regosols or regosolic soils. Total 
area of the association is 13 square miles, 
which is one-fifth that of the Latosols from 
Breccias. Latosols from Tuffs occur only on 
Babelthuap, mainly in the northern half of 
the island. 
The land surface of this soil association is 
highly dissected. Topography is mostly hilly 
to steep with local relief in many tens of feet. 
Ridge crests are commonly narrow but valleys 
are fairly broad with much fill. Occasional 
uplands have been dissected so as to resemble 
miniature Badlands, which are conspicuous 
though small. 
A profile description to represent the 
Latosols from Tuffs follows. 
(a) Setting . The profile was described and 
sampled south of the village of Aimeong, 
west central Babelthuap. The site was a 25 
per cent slope to the west in uplands about 
100 feet above sea level and less than 100 
yards from a mangrove swamp. The vegeta- 
tion at the site consisted of coarse grasses and 
low shrubs. 
(b) Profile Description . 
A 
0-3' 
B 
3-18' 
Ci 18-42' 
Reddish-brown (5YR 4/4) 
silty clay loam; weak me- 
dium granular structure; 
soft, friable; many fine and 
medium roots, few worm- 
holes and pinholes; strong- 
ly add. 
Yellowish-red (5YR 4/8) 
silty clay; weak coarse and 
medium subangular blocky 
structure; slightly hard, 
firm, slightly plastic, slight- 
ly sticky; many fine roots; 
few pinholes; strongly 
acid. 
Bedded deposit of weath- 
ered tuffs in which the 
main layers are variegated 
weak red (1QR 4/2), red 
(10R 4/8), pale yellow 
(2.5Y 7/4), and white 
(2.5Y 7/2) silty clay loam 
that is soft and friable. In- 
tercalated layers are red- 
dish-yellow (7.5YR 6/6) 
silty clay that is hard, firm, 
slightly sticky, and slightly 
plastic. The whole horizon 
has weak, very coarse platy 
structure inherited from 
original deposit and is 
strongly acid. 
C 42-60" Variegated weak red (10Y 
4/2) and pale-yellow (2.5Y 
7/4) silt loam with very 
fine white (2.5Y 8/2) 
specks; massive; soft, very 
friable; strongly acid. 
Major differences among the Latosols from 
Tuffs are in thickness and color of solum. 
Approximately half of these soils have solums 
IVi or more feet thick. Another fourth have 
solums between 1 and IV 2 feet in thickness. 
