No. 379.] REVIEWS OF RECENT LITERATURE. 537 
GEOLOGY. 
Lavas and Soils of the Hawaiian Islands.'!— The rocks of the 
Hawaiian Islands, with the exception of limited accumulations of 
coral and calcareous sands and a “remarkable felspathic andesite ” 
reported by Dana, are basaltic lavas. The surface lavas have been 
changed to soil by two processes: first, by the action of heated vapors 
charged with sulphuric acid; and, second, by the normal processes of 
weathering. 
The vapors now escaping through fissures over large areas within 
the crater of Kilauea at times contain as high as 4.92 per cent of 
sulphuric acid, and ranging in temperature from the lowest to the 
last point of condensation. In many instances the wals of the 
fissures, through which the acid-laden steam escapes, are luminous 
with heat at night. Marked chemical changes in the rocks are in 
process about these solfataras, and similar alterations have been 
observed at a distance from recent volcanic activity, where “ poison 
soils ” prevent the growth of vegetation. 
he sulphurous vapors, acting on the heated basalt, disintegrates 
it, changing the lime into gypsum, the aluminum and alkalies into 
alum, and the iron into the ferrous sulphate. These products sepa- 
rate out in distinct masses, and impart to the soil various colors and 
properties. The iron, upon exposure to the air, changes to the 
hydrous ferric oxide, and gives rise to laterites. 
Geologically, the soils are classified into three types : 
1. Dark Red Soils: Those derived from normal basalt by simple 
weathering in a hot, dry climate, — the red color being imparted by 
the anhydrous ferric oxide. They are the most fertile soils. 
2. Yellow and Light Red Soils: Those derived from lavas, which 
were first altered by the action of sulphurous vapors, and subjected 
to subsequent weathering in a humid climate. The color is due to 
the hydrated ferric oxide. As a type they are generally lacking in 
fertility. 
3. Sedimentary Soils: Those produced by disintegration of lava at 
high elevations, and then subsequently removed by rain-wash and 
streams to lower and flatter lands. 
When compared with the glacial soils of America, the soils of the 
1 Maxwell, Walter. Lavas and Soils of the Hawaiian Islands. Investigations 
of the Hawaiian Experiment Station and Laboratories [Established by the 
Hawaiian Sugar Planters Association], pp. 1-186, map and four plates. Honolulu, 
1398. 
