394 BOTANICAL GAZETTE [NOVEMBER 
Cinder cones 
The slopes and summits of all four of the great mountains are 
thickly sprinkled with cinder cones (fig. 9). These vary in height 
from 200 to 1000 ft., with very steep slopes of 30-40°. They are 
composed of volcanic ash, cinders, scoria, and other ejecta, and 
are frequently strewn with volcanic bombs and other lava blocks. 
These cones are most numerous on Kea and Hualalai; they are 
plentiful in the caldera of Haleakala and on the leeward slopes, 
and are by no means infrequent on the broad flanks of Loa. Many 
of these cones are more or less completely covered with vegetation 
and are conspicuous from a dis- 
a tance, serving as landmarks. 
‘ PIT CRATERS.—A second 
Bat 2 type of volcanic vent of distinct 
¥ ecological interest is the pit 
: crater (figs. 10, 11). This is 
f typically a circular pit, its 
ey mouth flush with the surround- 
ing country, its walls vertical or 
eee ty funnel-shaped, and its floor 
Fic. 9.—Summit plateau of Mauna littered with volcanic débris. 
Kea, showing numerous cinder cones; In diameter these pits vary from 
all high mountains of Hawaii, from sea Oe Peek COs Ye a 
level to summit tegions. case of the smaller ones) to 
several miles in the case of the 
gigantic pits of Kilauea and Loa. The pits of greatest botanical 
interest are those of intermediate size, namely, 100-300 yards in 
diameter and of similar depths. There are many pits so deep and 
narrow that no floor is visible from the rim. 
The pit craters occur indiscriminately in the rainy forest zones 
and on the barren slopes and summits. In the former case they 
are densely filled with trees and jungle litter; their mouths are 
often hidden by vines and other vegetation, and they constitute a 
serious menace to the traveler and to livestock. Those that occur 
in the arid sections are of particular botanical significance, as their 
steep walls prohibit invasion by cattle and goats, and the vegeta- 
tion within them is unmolested. Thus they constitute botanical 
