54 
PACIFIC SCIENCE, Vol. IX, January, 1955 
TABLE 5 
Chemical Composition of Sediments Found Along the Shores of Meyer Lake, Molokai 
description of erosional materials 
Si0 2 
per cent 
ai 2 o 3 
PER CENT 
Fe 2 0 3 
PER CENT 
TiQ 2 
PER CENT 
MnO 
PER CENT 
Silt from lake bottom 
13.. 77 
16.80 
30.64 
22.36 
0.17 
Coarse ferruginous concretions collected from 
shoreline of lake 
8.62 
9.50 
46.70 
20.56 
0.07 
Small pebbles found along shoreline 
20.05 
13.40 
35.16 
6.32 
0.14 
The ratio of ferrous oxide to ferric oxide was 
low in the soil samples, ranging from 0.16 to 
0.80. This ratio was extremely low in the 
concretions, 0.05 and 0.07. 
The data given in Table 5 were obtained 
from the analysis of the shoreline sediments 
of Meyer Lake. The silt from the lake bottom 
contained 22.36 per cent titanium oxide. The 
black crystalline minerals of titanium and iron 
oxides were easily identified in the water de- 
posited silt. The coarse ferruginous concre- 
tions found at the foot of the slope, but on 
the shoreline where wave action could sort 
the material, contained 20.56 per cent tita- 
nium oxide. Other sorted soil aggregates hav- 
ing a lower specific gravity had a much lower 
titanium oxide content, 6.32 per cent. The 
iron oxide content of all of these materials was 
greater than 30 per cent. The silt material 
would have an appreciable amount of free 
titanium oxide. 
SUMMARY 
The titaniferous-ferruginous laterite areas 
in the Meyer Lake area of Molokai have been 
investigated to determine the nature of the 
weathering processes responsible for their de- 
velopment. The soils of this area belong to the 
Naiwa family of the ferruginous humic latosol 
group. These soils have accumulated iron and 
titanium oxides in the surface horizon. In- 
durate, concretionary, slaglike surface areas 
form on the slopes as a result of dehydration 
of the soil minerals. The concretion content 
of these indurate areas ranges from 30 to 43 
per cent of the weight of the soil. 
The soils of the indurate layer have a much 
higher content of titanium oxide and iron 
oxide than the hydrated friable soil in the 
adjacent areas. The highest content of iron 
oxide in the soil was 53 per cent and of tita- 
nium oxide, 21 per cent. The concretions were 
made up predominantly of iron oxide which 
amounted to as much as 72 per cent of the 
weight of the concretion. The titanium oxide 
content of the concretions ranges from 11 to 
13 per cent. The occurrence of these oxides 
in concretions is conclusive evidence of their 
movement in soluble form, as the develop- 
ment of concretions can only be considered 
to be a product and a phase of weathering 
synthesis processes. 
The fractionation of free titanium oxide and 
combined titanium was attempted through 
the analysis of these samples for ferrous oxide. 
The maximum possible content of ilmenite 
would be obtained when all of the ferrous 
oxide is assumed to occur in the mineral 
ilmenite. The data obtained by this analysis 
revealed that in the indurate soil and concre- 
tions, it was possible for appreciable quan- 
tities of titanium to exist as the free oxide. 
In some of the soil, at least half of the tita- 
nium existed as the free oxide, anatase. 
The titanium and iron oxides accumulate 
in erosion sediments due to their specific 
gravity. There is a substantial difference be- 
tween characteristics of the erosion deposits 
and the indurate layers. 
