The Pacific commercial advertiser. [volume] (Honolulu, Hawaiian Islands) 1885-1921, 1886-03-26
The Craters of HOkuaweOWcO on
Mamma I4Oa.
(ConcIuded.)

70 the north, and thence clambered out
to the east OF Mokuaweoweo by the ex-
tremely interesting route OF a former
cataract Of lava from the summit into
the crater, the swift downfall OF which
had turned its lava almost into pumice,
and the black, shining spray OF which
lay spattered on the surrounding rocks.
Further south observed the course OF
two other cataracts, which had poured
directly into the central crater. At the
summit l found the deep fissure from
which the outbreak had come that
caused these cataracts, and ascertained
that it had also poured an immense
stream north upon the first plateau and
thence south to the central crater. Cross
ing from this place to the north over the
first plateau I suddenly came TO fright
full circular crater in the bed OF the
plateau, apparently 60 feet deep and
1 900 feet wide, with cone in its center
still smoking. We were obliged to hurry
with exhausting speed over rough lava
in order to reach our tent before night.
The next day we took the transit to
the stations in the crater, and the next
we surveyed with it along the western
brink TO the extreme south end, where
we looked down into the South Crater,
which is about 800 feet deep and $500
feet wide The length OF the whole
chasm, or ''caldera, - have ascertained
to be about $4,000 feet, the greatest
breadth 5000 feet, and the greatest depth
800 feet The area is three and six
tenths square miles. A map of these
craters has been sent to the Government
Survey Office.
On the southwest side, near the june
ton of the central crater with the south
plateau, l found that there had been
another eruption, from assures that were
| still smoking, and that this eruption had
poured an immense stream southwark
towards Kahuku, and had also poured
cataracts into the South Crater from all
sides
had everywhere observed that there
had been great flows from the summit
brink down the mountain, and had
wondered at the thought of the vast
chasm having filed up and overlooked
it's brim
This, however, turned out to be an in
correct view. The flows have not been
from the lowest parts of the brim, but
from some of the highest, which could
not have been the case in an overflow.
The walls of the craters are largely
composed of loose, old weather-beaten
rocks, and large tracts OF the plateau are
composed OF old pahoehoe, that has not
been overlooked for ages, which would
not be the case if the craters filled and
overfOwed.
These outbreaks from assures around
the rim indicate that the lava has rather
poured into the crater than out OF it /;
and that it has poured from such assures
in vast streams down the mountain side.
What enormous quantities of lava may
flow from such small assures is illus
| trated by the flow of 1859. The aues-
ton arises, how has the lava risen high
enough to pour in extensive eruptiOns
through these assures, almost a thou
sand feet above the bottom of the crater,
without rising in the crater and overflow
ing it? The same question has often
been asked in respect to the rise of liquid
lava to the summit of Mauna Loa with
out overlooking the open crater of XII
lauea, 10000 feet below.
We have seen that it is not because
the lava in Mokuaweoweo is lighter than
that in Kilauea that it rises 80 much
higher. In fact, it is as solid there as
in Kilauea. The explanation has oc-
Cured to me that molten lavas rise the
higher the smaller the conduits in which
they rise from their subterranean reser-
voirs
An illustration is afforded by the
"spouting horns" on the seacoast, where
the ocean rushing into caverns of rock,
drives columns of water through small
openings to the height OF 40 or so feet
above high-water mark. We see another
illustration in water conveyed in pipes,
which jets the higher the smaller the
Orifce.
However violent the subterranean
pressure may be, Kilauea does not over
flow, but only RACES the more fercely,
because its passage from the chambers
below is so large. But through the vast
mountain of Mauna Loa there is no
doubt CONSTRUCTED conduit leading up
ward; and there must be still smaller
conduits to the assures on the summit
rim. On this theory, the molten lava
rises higher through Mauna Loa than in
Kilauea, because Mauna Loa has the
smaller throat.
1t is therefore by no means certain
that there is no subterranean connection
between the two volcanoes.
Another vexed question, of which
several solutions have been proposed, is
the mode of formation of the two strongly
contrasted forms of lava known as "pa-
hoehoe' and "aa." The former term is
applied to tracts of comparative smooth
and uniform lava, as though it had cooled
while flowing quietly; the latter to tracts
of broken lava, as though it had cooled
when tossing like an ocean in a storm,
and had then been broken up by earth
quakes. As Mr.. Brigham states, "No