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PACIFIC SCIENCE, Vol. II, October, 1948 
from 2 inches thick on the northeast to 12 
inches on the south near Keanakakoi. 
The surface of this deposit shows the effects 
of prolonged exposure and wind erosion (Plate 
4C) in every area, but no humus layer accumu¬ 
lated on the windward rim. 
The remnant deposits on the crater rim from 
the 1790 eruption (Finch, 1947: 1) range in 
thickness from about 3 inches on the windward 
rim to a maximum of about 44 inches on the 
broad fault block forming the inner, western 
rim of Kilauea (Fig. 2F). At this locality, the 
deposits indicate at least three main explosive 
phases. The lowest layer is 8 inches of lithic 
fragments (up to 2 inches in diameter) grad¬ 
ing up into a thin layer of fine lithic sand. The 
middle layer is 12 inches of unsorted, fine to 
coarse, lithic fragments capped by a thin layer 
of lithic dust. The upper layer, 24 inches 
thick, consists of 18 inches of medium to large 
lithic blocks (up to 6 inches) grading up into 
4 inches of coarse to fine lithic sand, grading 
into 2 inches of fine lithic dust. A mile south, 
on the southwest rim, the deposit is about 12 
inches of unsorted, fine to coarse, lithic frag¬ 
ments, and it continues in similar thickness and 
composition around the south rim to the section 
due north of Keanakakoi. From this point north¬ 
east along the rim, the deposit thins very rapidly 
to 3 inches in less than a quarter of a mile 
(Plate 1A). On all of the windward rim, the 
deposit consists of unstratified material ranging 
from dust to pebbles approximating a hen’s 
egg in size, now mixed with humus as well as 
some indistinguishable, fine material from his¬ 
toric eruptions. It makes up the bulk of the 
present surface soil, though there has been no 
chemical decomposition of the lithic fragments. 
On the leeward desert rim, except where it is 
covered by later deposits, coarse fragments from 
this deposit have been concentrated and fine 
material has been crusted to form the stony 
pavement characteristic of the desert surface. 
The thickness of this deposit decreases rapidly 
in all directions away from the crater. A maxi¬ 
mum thickness of 6 inches can be found on the 
outermost rim due west of Halemaumau at 
3,800 feet altitude, on the broad slope east of 
Cone Peak at 3,600 feet, and due south of 
Keanakakoi at 3,600 feet. The size of fragments 
decreases and the proportion of dust increases 
with distance away from the crater rim. Many 
blocks with a volume exceeding a cubic foot 
and a few with a volume exceeding a cubic 
yard are found on the rim around the south¬ 
westerly half; fragments up to 6 inches in 
diameter are found to the southwest as far as 
Cone Peak; fragments up to 2 inches in diam¬ 
eter are not rare to the southwest as far as the 
3,400-foot contour; and many fragments reach 
half an inch in diameter near Mauna Iki at 
2,900 feet. 
The deposit is made up almost entirely of 
crystalline fragments and contains no juvenile 
vitric pumice, though, in a small area, bread- 
crusted blocks and cored bombs are common. 
Near Keanakakoi, such fragments make up 
nearly 1 per cent of the deposit and blocks and 
cored bombs up to a cubic foot in volume are 
found as much as half a mile from the crater 
rim. They are very rare in the other quadrants 
of the crater rim. The insignificant amount of 
still-plastic material (at time of eruption) rep¬ 
resented by these bombs is considered to have 
been "bench magma” left behind by the abrupt 
withdrawal of the active magma column, and 
the eruption is believed to have been made up 
entirely of phreatic explosions. 
Correlation of specific eruption layers in sec¬ 
tions somewhat distant from the rim of the 
crater is almost entirely speculative. On wind¬ 
ward slopes an appreciable thickness of ma¬ 
terial was deposited by very few eruptions, 
and any thin deposits lost their identity 
by incorporation in the then-existing, surface 
soil. To leeward, immediate attack by wind 
erosion rapidly destroyed most thin layers of 
ash, adding the coarser materials to the moving 
sand dunes and transporting the fine material 
entirely out of the area in which it was depos¬ 
ited. Beds of water-saturated pisolitic mud 
which have been partly consolidated and sur- 
