460 
PACIFIC SCIENCE, Vol. XXII, October 1968 
TABLE 1 
A Sequence of Soils Occurring with Increasing Rainfall on a Single Basalt Flow on the 
Island of Kauai from Anahola to Waipuhi Falls in a Distance of 6 Miles 
Dry months 
8-9 
4-5 
2-5 
2-4 
0-2 
Wet months 
3-4 
4-5 
4-6 
5-8 
8-12 
Total rainfall 
40-45 
50-70 
70-100 
100-150 
150+ 
Soil family 
Kahana 
Puhi 
Haiku 
Hal ii 
titaniferous 
phase 
Koolau 
Great soil 
Low Humic 
Ferruginous Ferruginous Aluminous 
Hydrol 
group 
Latosol 
Humic 
Latosol 
Humic 
Latosol 
Ferruginous 
Latosol 
Humic 
Latosol 
Clay minerals 
Halloysite 
Halloysite 
Goethite j 
1 Halloysite 
Kaolin 
70 
35 
Hematite 
! 30 
50 
in order of 
Goethite 
Geothite | 
| 45 
Gibbsite 
Gibbsite 
20 
Hematite 1 
| Gibbsite 
30 
15 
abundance and 
Ilmenite 
40 
25 
Anatase 
Anatase 
5 
Anatase ] 
1 Halloysite 
30 
15 
in per cent of 
soil 
Ilmenite * 
10 
Gibbsite 
10 
[ 20 
Anatase j 
Ilmenite i 
10 
Goethite ) 
[ Magnetite j 
I io 
Goethite 
10 
Parent material 
Kaolinized 
Kaolinized 
Ferruginous Ferruginous 
Possibly 
of soil 
basalt 
basalt 
bauxitic 
saprolite 
bauxitic 
saprolite 
volcanic 
ash 
Parent rock 
Basalt 
Basalt 
Basalt 
Basalt 
Basalt 
formed where the annual rainfall is 15 to 40 
inches, with the help of some low rainfall inter- 
grades. The intergrade soil will have decreasing 
amounts of 2:1 layered alumino-silicate clays 
with increasing kaolin clay content as rainfall 
increases. The peak of kaolinization will occur 
in soils developed under about 35 inches of 
rainfall. An excellent sequence of this type can 
be found on the island of Oahu near the West 
Loch area of Pearl Harbor. Beginning at this 
point, and following the Kunia road, one en- 
counters, in order, soils of the Honouliuli family 
— > Molokai family — > Lahaina family developed 
on alluvial materials. These soils are formed 
under 15 inches of rainfall, in the case of the 
soils of the Honouliuli family, to 35 inches for 
soils of the Lahaina family, and show the min- 
eral relationships described as above, from mont- 
morillonite type of clay minerals to a completely 
kaolinized profile. 
SOIL SEQUENCE DUE TO AGE 
Mohr (1944) has pointed out that soil for- 
mation progresses through stages of development 
ranging from youthful to senile. Soil formation 
is a dynamic process which proceeds at various 
intensities depending on the weathering environ- 
ment. The influence of time on soil formation 
has been studied in the Hawaiian Islands. At- 
tempts are being made to study sites which have 
identical climatic conditions with comparable 
parent materials. Since age is the variable being 
studied, it is impossible to find on a single 
island soils showing a sequence of the effect of 
this soil-forming factor. Therefore, to make 
this study, it is necessary to select sites on differ- 
ent islands. 
The first observed effect of age on soil for- 
mation is the disappearance of soils of two prom- 
inent great groups occurring on the geologically 
young islands of Hawaii and East Maui — soils 
of the Reddish Prairie and Latosolic Brown For- 
est groups. These soils are absent on the older 
islands with the exception of a small area on 
Molokai having soils of the Oli Series which 
belong to the Reddish Prairie group. However, 
the soils of these two great groups, on chemical 
and mineralogical examination, show evidence 
of strong development of Latosol features. Both 
soils have weak A x horizons which grade grad- 
ually to a lighter-colored B horizon, which in 
