The Hawaiian gazette. [volume] (Honolulu [Oahu, Hawaii]) 1865-1918, 1884-09-10
Dawaiiatr Gazette.
WEDYEsDAY. sEPTEMRER 10 1854.
The Volcanic Problem From the Point of
View of Hawaiian Volcanoes.

paper on Hawaiian Volcanoes, which &C
! companies the Annual Report of the Di-
rector of the United States Geological
| Survey for the year ending June 80, 1888,
! has called attention TO certain phases OF
volcanic action on Hawaii which deserve
! the careful attention of all vulcanolOgists.
! At page 1914 he observes: ''ghey," THAT
| Is. the volcanoes of Mauna Doa and kilau-
! ea) bring up more lava and dIsslpate
more energy in the course Of a century
! than any others of which we have knowl-
! edge. Their action Is also the least OBJ
streperous. That they should give OF the
! greatest amount of energy in the quletest
manner, Is surely a most curious and strlk-
| ing fact. but it does not imply anything
radical or anomalous But in any cate
! CORY of facts extreme cases are always
! deeply interesting and sometimes highly
! instructive
Captain Dutton considers the usual ny
| potheses which are offered as the main
/ moving causes of volcanic action, or the
power which raises and maintains vast col
umns of molten rock above the surface of
| the earth-as inadmissible. He reviews
rapidly the hypothesis of the percolation
of water to the heated rocks, as well as
| that Of the original mixture Of the molten
rock with water; also the oxydizing or
chemical hypothesis, and the crushing,
heating and melting theory of Mallet, and
| finds each one entirely unsatisfactory;
while the expansion of hot solid bodies on
relief of pressure, and the assumption OF
| local inCrements of heat, he dismisses as
hardly worth refuting.
Captain Dutton however, in studying
! Hawaiian volcanoes adyerts to principle
Of action which have long looked upon
as main factor not only of the action in
| these crateTs but one which illustrates the
general principle of volcanic action the
world over
AT page 196 he observes: In the Cal
! deras Of MokuaweoweO and Kilauea, the
| lava lakes represent the submits of col
Umns of liquid lava extending to depths
in the earth which are probably very great.
! When great eruptions occur on the flank
of the mountains at lower levels, these
| lakes are drained, and when the erup
| tons cease the lavas come up in them
| again. to their former level. But in the
| history Of the mountains the heights of
these liquid columns have not been con
slant, but have steadily increased. In XII
lauea this has, to our knowledge, increased
rather more than 400 feet in the last sixty
years. Taking all the circumstances into
consideration, IL scans as Il Tic SUBMITS Of the
columns IN each case rerc approximate equilib-
rum lcUels depc,,dcH utmost solely upon their
man density at any gicea time THE italics
are mine)
Captain Dutton further advocates the
probable existence of two important facts
in any attempt at explanation of volcanic
| action; namely, a universal liquid or highly
plastic substratum, and the fact that cold
| solid lava Is denser than hot molten lava.
\ If this be the relative condition of the
| earth's solid crust and the liquid substra-
tum. may not this difference of density be
| the simple missing factor" which causes
all lavas TO appear at or above the surface
of the earth?
Captain Dutton seems however, to con
slider page 1S4) that the hypothesis of the
universal underlying magma being of less
density than the crust which rests or floats
upon it, is not one that Is admissible In
this view | am aware that he is sustained
by one of the most able physicists and
mathematicians of the day, Sir William
Thomson, who in an address at the Glas-
gov meeting Of the British Association in
1876 has given it as his opinion that under
such circumstances the fractured crust
would sink like rammed ironcladr
Taking all the facts as they probably
exist however, it does not seem necessary
TO conclude that the denser crust of the
earth should sink far into the less dense
upper layer of the magma upon which it
may rest; for,
First. 1t is admitted that the density
| Of the liquid underlying magma-if il ex.
iefe ,r-,4h al, ,l,,,4l, -.
| increase very rapidly at first, both because
the density must increase with the pres
sure, and because the iron and other heavy
components, in all probability increase in
quantity as the depth increases.
Second. The earth's crust even when
divided into segments by assures, must
be supposed to be resting upon the liquid
substratum very much as the arch stones
of bridge are placed, and as the hot
| liquid contracts more than the cooler solid
crust, from loss of heat, the simple weight
OF the crust tends to close the assures. and
the farther the crust descends, the closer
the assures tend to become.
Third. The liquid into which the crust
IS supposed to be sinking is entirely diff.
terent to that into which the ironcl8d sinks,
for the moment the molten lava becomes
exposed to radiation in the atmosphere or
even to loss of heat by conduction in
narrow tissure, 1t tends to freeze solid, heal
the crack, and prevent any further sink
ing
But as matter of fact we know that frac-
lures do exist in the earth's crust and the
lava flows out over them sometimes in
enormous floods, while at other times it
| builds up cones of solid rock and rises in
| conduits in the center of them far above
the mean surface of the earth. 1t may be
only question of the relation between
the density of the lava and the crust, how
far the liquid column has to build itself
up, to place everything in a state of equi-
llbrium, and to prevent any further sink
ing Of the crust, even if the increasing den
sity below did not do So
This principle is partly illustrated in
pool covered by ice in a heavy frost and
upon which is a number of skaters. The
mean density of the ice including the
weight of the skaters may be greater than
that of the water, and when crack occurs
IN It the water will often appear above the
surface, and yet in heavy frost there is
| little danger, as the water freezes rapidly
| and thlckens the ice or heals the crack.
But, we are told that if the appearance
VI llle uOlbeu SuDSIaIum above the sur
face Of the crust be due to the weight of
the crust, the lava in each of the different
volcanoes should stand at the same level
and the instance of the liquid columns in
the conduits of Kilauea and Mauna Loa
Is constantly brought forward by geolo-
glsts to prove that inasmuch as they con
stantly stand with the surface of the one
some 5000 TO 10000 feet above the level
OF the other, it is impossible that they can
be connected with the same interior LIQUID
mass. A little reflection, however. shows
that this does not necessarily follow. II
Is well known that large portion of the
| upper and interior masses of Hawaiian
mountains have a density when cold of
| about $50, whilst the more basic or olivin
ltlc outtiows on the lower slopes have very
commonly density of 80. If we NAV
suppose that the same proportionate diff
ference exists in the density of the molten
columns Of lava in Kilauea and Mauna
Loa, and assume the thickness of the
earth's crust beneath the top of Mauna Loa
to be . miles, this alone would cause near
ly the difference in height of the two col
umns which actually exists But indepen-
IDENTIFY of the difference in composition,
the heat of the more powerful column of
Mauna Loa, and which is usually closed
column that is not exposed to radiation.
NAV be expected to I've much trraatar tban