Evening star., 1897-03-26
HAWAI|'S FERTILITY
Hve -
The Black Loan and Sand From the
Lava Flow.
WHAT UNDERLIES RICH PLANTATIONS
Use of Artesian Wells to Irrigate
Coffee Fields.
RICH, RONG NDS
Special Correspondence of The Evening Star.


The geological formations of the Hawaii
an Islands may be mainly expressed by one
word-lava. The mass of the entire group
is built up of that one mineral In its nu-
merous varieties. not greatly differing from
each other. A one-hundredth part may be
composed of volcanic ashes and tufa, which
are only what might be termed the frotk of
lava Perhaps one-thousandth part may
be calcareous coral and shell sand, some
OF it oemented into sandstone
Lara is the rock that wells up through
the shafts of volcanoes, white hot from the
molten interior twenty-five miles beneath
the crust. 1t spreads out and coois in vast
uneven beds of rugged rock, full of vesicles
or spongy cells, except where 1t has filed
some deep cavity where the pressure COM
pacted 1t. This lava rock is very COM
pound, mixture of almost all known min
eral elements, but none of the valuable
metals. except iron, in more than homeo-
pithic quantities. And the iron is only
enough to color 1t red when oxidiZed
Hence none of these Hawaiian rocks have
any mineral value and there is no work for
the miner. Much of the more compact
lava Is available as an excellent building
stone. very durable, and hewing more easily
than granite. Honolulu is studded with
new business blocks fronted with this
blush gray lava. of which we have noun
are built entirely of it,
Perhaps our five hundred cubic miles CT
Ihese lava rocks contain as much gold as
qoes sea water, and as equally diffused
l DeleVe there are several thousand billions
OF gold in the ocean, but it's profitable ex-
traction is hopeless. Nature has a mar
Feious alchemy by which in the lapse of
mliAohs OF years the vast plutonic rock
masses or the continents, once lava like
ours, undergo slow secular change aud.he-
come transformed. and veins and Iodes of
Ealuih!e and precious metals gather in
their recessas. Here our rocks are yonnp
pei iaps none OF them a million years old,
and can yield nothing for the miner nei,h .
er Goii iron, coal nor Jewels There are
no strained rocks because nc LAYERS have
peen deposited by water except what is
sun peheath the ocean. Yes, there are
strata OF tufa in very even LAYERS These
raihed down from, the atmosphere in the
form OF hot mud. which was spouted miles
aioft IN a volcanic throe and cementeI . G
~ Ia leil, olteh incasing many square miles of
sen surrounding the fiery vent There are
several square miles on the Oahu railway
Just out OF town. which are covered h,.
from rom SIX TO twenty feet of these layers Of
soit rCck' which overlie great thicknesses
OF alluvial soil. or of coral
The Site of Honolulu.
Much OF the fiery mixture of lava and
water Snot forth from sudden crupttons of
'he explosive kind, so expanded while aIoft
as u COOL IN the form of spongy sand. or
volcanic ashes. before falling. This citv
Vi honolulu rests upon such bed of from
three to eight feet of black ashes or s,,d
everything coral. On lower Fort stree. tho
cellar OF new brick block is now being
excavated. 1t goes through eighteen inches
OF brown loan, then four feet of the black
sand The upper loan is ONLY the black
ashes decomposed by air and moisture The
ashes or sand will mostly be sif1ed for
mortar. The coral below this will be level
en TO the proper depth. This coral sub
stratum was ancient reef formed under
water but now raised considerably above
sea level. The whole of this Island of Oahu
mad originally undergone slow subsistence.
perhaps for half a million of years settling
many thousand feet as is well ascertained
AT very recent period, however probably
not over 5000 or 10000 years there was
an apparently quite sudden elevation of the
whole island. varying in parts from thirty
TO fifty feet. This converted into dry land
large stretches of what was the fringing
reer. 1t is not exactly true coral but a
ccncretion of fragments of coral, shells.
madrepore tubes, and calcareous mud,
forming coarse, whitish rock Most Of
this coral within the town became buried
deeply with the black cinders or sand.
which seem not long after to have been
shot up from the great cinder-cone inland
about 2,UD feet high, known as Mount
TantaluS.
The main mass of the volcanic noun
tains forming this island are evidently
many hundred thousand years old as in
dlcated by the great extent to which II ha =
Weathered away, under the slow erosion of
rain storms and the torrents generated by
them. Except near the bases of the origi-
nal mountain dome, no traces remain of the
once rounded form. Only sharp serra:ed
ridges are left where the now wide gulches
nave eaten into each other. Many of these
ancient ravines have had their outlets at
the shore obstructed by very recent tufa
cones, such as Diamond Head and Punch
form IIrh
marks to Honolulu. In such cases new
outlets have been formed for the strea ms
There seems to have been a very recent
period of fresh volcanic convulsion around
the shore Of the island, perhaps coinci-
dent with the changes attending the close
of the glacial period.
While HI this city the foundations OF most
of the heavier buildings extend down to
the solid coral, this is by no means neces-
sary. The black sand is itself so compact
as 10 furnish a safe foundation for the
heaviest structure. Our builders long ago
learned TO rely on its solid qualities Both
OF the massive churches, the Central Union
ard the Anglican Cathedral rest upon
tnis sand A neat story is told about the
latter After the heavy founia Iions of the
Cathedral had been finished, some thirty
years ago. the good Bishop Staley's mind
misgave him. He began to institute further
inquiries about the sandy basis on whic n
those foundations rested Among other
persons he resorted to the Catholic hishon
who rejoiced in a huge cathedral of his
own. Bishop Maigret will you kindly ir-
form me whether the foundation of vcur
church goes down to the rock or rests upon
the sand?' Our church." the old preia te
ponderously responded. 'is founded upon
the rock" He scored one that time for st
Peter.
This black ash is an admirable fertilizer.
although 1t is slightly poison Gus to veReta-
ton until decomposed by exposure to air
and moisture. Hence the roots of trees sell
dom penetrate 1t. Volcanic ash Of like
structure, but more commonly yellow. ex-
lists In several other localities and IL AL
ways extremely fertile. There are about
four square miles OF such soil under the
prosperous Haua plantation, at the eastern
angle OF Maui. where the country is warty
with cinder cones. At the southwest angle
Of the island Is nearly as much more. A.
Kau. on the south end Of Hawaii is a re-
markable deposit Of yellow ash covering
over 100 square miles to depth of ten to
thirty feet. This must have been the ef-
feet of single explosion of few hours.
duration, comparable to the enormous over
throw of Krakatau in 1888 1t probably
took place not far from a thousand years
ago. This Kau ash is excessively pro
ductive. but unfortunately receives scant
rainfall In most parts, while irrigation is
forbidden by the impossibility of water col
lecting on the new lava Of the rainy forest