New-York tribune., 1902-05-14
CAUSES OF ERUPTIONS.
NO CONCLUSIVE WORD on THE SUB
JECT IN "a TEXTBOOK OF
GEOLOGY"

A recent publication by the Appletons, en-
titled "A Textbook of Geology" by Albert Perry
Brigham contains this the subject of vol
canoes:
volcanoes make a immense contribution to the
tioa Of the sea bottom by election of fragmental
matter. Indeed, We should not think of volcanoes
(and the same might be said of glacers) as alb
normal or exceptional parts OF the economy of the
molten state, blown into dust and bits of larger
size by stupendous explosions. This is the origin
sense products of combustion but rather of intense
mechanically applied energy So great is the guam,
for hundreds of miles and the surface of the sea
covered for long distances from the seat of the
thiTty-fve miles from one of the Nicaraguan vol
TO a depth Of ten feet. Dust from an Iceland VOL
cano has fallen in such quantities as 10 be shov,
eled from the decks or shlps near the orkney ana
Shetland Islands, while in 1873 ash from the same
ScotIan5 so largely as To destroy crops The sea
son was remembered as the year of The Ashie'
ranging TO that of walnut. they are called api.i;
Sometimes huge blocks. either of the older and
hardened lava, the country rock through
height and distance Lumps of molten lava are
also cast into the air. and cool while under the in
fUence of rotary motion, assuming variety OF
pear shaped and disklike forms These are known s,
an Mn inch or two to one % or more feet o,srf rains
and the water mixes with the volcanic ash, often
in mud flows of considerable extent. Such mud
or the ash consolidating IN the place Where IL mas
fallen, makes the volcanic rock known as tuta,
volcanic regions
The writer gives a concise history Of Vesu-
vius, Etna, the Hawaiian volcanoes, Krakatoa
and the volcanoes in the Atlantic region. As to
the causes Of volcanic action the author says:
WHAT CAUSES EXPLOSIONS.
No conclusive word has been spoken on this sub
ject A final conclusion may lie beyond the bounds as
the Ice Age, earthquakes, or the origin of species
be doubted. but the ultimate cause Yet lies
in obscurty- This is not discourag1ng TO the true
student but only one of many proofs of the limi-
tatiOn Of our knowledge. 80
Two questions must be asked: a. What are the
sources Of the heat needed to melt the rocks and
form the gaseous clouds OF vast extent? l0 What
been given which must be set aside. or at least
thought TO be a remnant of the original heat of
the glche. But on this theory It would seem that
vulcanism should gradually have declined through
proved and some facts look in the opposite direc-
Iion. Others have thought that the heat comes
from powerful chemical reactions in the deep
natural laboratories Of the earth's crust But this
cause seems insufficient for the melting that is
accomplished. II is known that rocks melt and be-
come plastic under great pressure in the presence
Of water and alkaline materials. This is called
great heat of volcanoes All these causes may
Contribute 10 the result various degrees and To-
believed TO hold The rocks Of t the crust near the
fae seh crh0g as eoe Wif6 Mountain ie maxi
ing may add heat enough Of mechanical origin 10
that the under rocks Would melt if they We're not
under stupendOuS pressure, and when at some
points this pressure is relieved in the succession Of
strains which the crust undergoes the rocks there
pass into a molten state. The two theories are
inconsistent. At point added
pressure and added heat; at another, removal of
pressure and lowering of the melting point.
As the cause Of explosion the answer IS hardly
into steam is thought TO have much to do with
explosive erupttons, and the most volcanoes
are near the sea. But this does account for
inland quiet eruptions. Nor is easy 10 see
how enough water could reach the seat Of the heal
either by saturation sudden inflow Chains of
volcanoes, in the Andes. correspond with lines
Of mountain making. perfect theory eX-
plain all the facts. Why some eruptions quiet
and others violent2 Why the differences in the
composition and heat Of lavas? Why should there
be a difference of 10000 feet in the height of the
lava columns in the adjacent volcanoes of Mauna
Loa and Kilauea2 Why some inter
mittent and others constant in action? Such are
some Of the questions No theory covers all Of
these.
The Storied West Indes,' by Frederick A.
Ober, is another little book published by D. APP
pleton & Co. in which considerable space is de-
voted to the volcanic chain in the West Indies.
Each island says the author. is a partly
submerged volcano its Sides and even the ex-
tinct crater, clothed with luXuriant growths.
Although there are several outlying islands, such
as Anegada, Saint Martin and Saint Bartholo-
new, the real chain of volcanic isles begins with
p pair of peaks belonging TO the Dutch, named
Saba ana Saint EustatiCs."