2 BULLETIN 6 2, HAWAII EXPERIMENT STATION- 
SOME FACTS RELATIVE TO TROPICAL SOIL FORMATION 
The soils of the Hawaiian Islands are almost entirely decomposi- 
tion products of basaltic lava or volcanic ash under more or less 
humid tropical conditions. Only to a very limited extent in areas 
near the seashore at or near sea level is the modifying effect of lime- 
stone in the form of coral beds noticeable in soils adapted to agricul- 
Figure 1. — -Undecomposed lava flow (a-a formation) 
Figure 2. 
-Field of volcanic ash showing the end of a recent lava flow (pahoehoe 
formation) 
ture. Both the nature of the original parent material peculiar to 
volcanic countries and the soil-formation processes typical of tropical 
or subtropical latitudes are responsible for the particular types of 
soil formed. 
Kelley and his coworkers (21) x and McGeorge (#4)? in former 
publications of the station, give information at some length con- 
1 Italic numbers in parentheses refer to Literature Cited, p. 41. 
