162 ~ HAWATIAN ISLANDS. 
from one to ten feet. The concentric folds or plaitings of the surface 
of the lavas were most distinct on the slopes of these bulging elevations, 
and it was therefore obvious that the bulging had taken place while 
the lavas were still free to move, and also that the plaitings had arisen, 
after the expansion, from the moving down of the liquid against the 
motionless lavas below. 
The folds and twistings in the surface of the lava, here explained, 
are the rtpple-marks of some authors on the Hawaiian volcano; and 
from the rounded hillocks and ridges the waves of a molten sea have 
been fancifully made out. 
Other regions consisted of lava and scoria in immense masses, piled 
together in the utmost confusion. They are styled clinkers or clinker 
fields. ‘They look as if the mountain had been shattered to a chaos 
of ruins. The fragments vary from one to ten thousand cubic feet, 
or from a half bushel measure to a house of moderate size. ‘They are 
of all shapes, often in angular blocks, sometimes in slabs, and have a 
horrible roughness beyond conception, points and angles standing out 
in every direction; they lie together, touching only by their edges or 
points, leaving deep recesses everywhere among them. Reaching a 
district thus bristled with scoria, we mounted on the blocks, and 
travelled by leaping from one to another; yet not without an involun- 
tary shudder, lest a foot slipping should precipitate us into the deep 
cavities, among the jagged surfaces and edges. ‘These clinker dis- 
tricts are often several miles in breadth; and upon some of them the 
whole horizon around is one wide waste of gray and black desolation, 
beyond the power of words to describe. 
The solid lava fields, (the pahothor of the natives,) and the clinker 
regions are generally associated together. In several instances we 
passed abruptly from the former to the latter, and then returned to 
the smooth lavas again. ‘There is no doubt that the whole was one 
single region of eruption, and these different results arose from dif- 
ferent phases in the volcanic action of one and the same period. ‘The 
clinker fields are usually twenty or thirty feet the highest, and the 
passage from one to the other is by a steep ascent. 
Clinker fields are a common feature over the whole surface of 
Mount Loa. They evidently proceed from a temporary cessation, 
(either complete or partial,) and a subsequent flow, of a stream of lava. 
The surface cools and hardens as soon as the stream slackens; after- 
wards there is another heaving of the lava, and an onward move, 
owing to a succeeding ejection or the removing of an obstacle, and 
