The Hawaiian gazette., 1896-08-14

built no mountain yet Mauna Loa is
older. but gives us an eruption about
once in ten years not second 10 any in
the world. Hualalai has broken out in
the last hundred years, and can hardly
be considered extinct. The next one in
age is more difficult 10 pick out Is it
Mauna Kea or Haleakala? From the
fresh lava, probably the lattee is the
younger There must nave been an
eruption within three hundred years
at the outside. 1t is strange we have no
traditions on the point. Lanai and Ka-
hoolowe are probably next, judging by
the slightness of erosion. But they are
small, and so it is uncertain. Kohala,
West Maui and West Molokai are next
and about the same age.
East Molokai is older, but about the
same as East Oahu. Waianae and Kau-
al are the oldest.
Still. there are evidences of COM
paratively recent eruptionS on all the
islands. While the ravines here are at
least 100000 years, old, and those in
Waianae older, yet there is lava here
* the base OF some of the mountains
that can hardly be older that 1000
years.
will they be renewed? Probably.
Can we tell when? Not certainly, but
Mauna Loa and Mount Etna have al
ways had their heavy eruptions, as far
as history shows, within few months
of each other. In fact there seems to be
| unanimity in the action of all the
volcanoes on earth that suggests COM
mon cause A coincidence between sun
spots and heavy rains on the one hand
and volcanic activity on the other. 1t
| is easy to see the connection of the
rains. The rains furnish water for the
vapor which causes the expulsion. The
connection of sun spots is not so easily
explained.
las we have seen, rock is formed in
TWO ways-by igneous and by sedi-
mentary action. Igneous action builds
up. We see this in volcanoes. But that
| is comparatively slight The great
work is done in the raising of mountain
systems by the wrinkling of the earth 5
crust On the other hand, the atmos-
phere and the ocean tear down. If
they alone were at work the earth
would be only low plain just above
the ocean.
The old definition of volcano was
a burning mountain. The trouble with
this is that it is never burning, and not
always q mountain. There are three
kinds of volcanoes-the lava cones
either fat like Mauna Loa when the
lava runs over in quantities and quite
| fluid, or steep like CotopaXi and Yes
uyius when the lava runs out in small
streams and not very fluid. Second
cinder cones, usually small, sort Of blow
holes, and having a crater on top
Third, tufa cones, when there is much
water and much steam is formed, car
rying out finely divided rock and de-
posting it in sedimentary way.
You can illustrate the lava forma-
lion to your classes by making plaster
of paris into thin paste, building VI
a crater with clay or putty, and pouring
the lava in. The plaster should be
tinted with red earth or lamp black
Clean out your crater after an eruption
and it will be ready for another.
For a cinder cone, sprinkle sand
through large pepper box in different
tints, one after another. 1t will form
a sort of irregular qualification.
ITO tell whether rock is igneous OF
sedimentary, look at the crystals; they
are igneous, while bands are found only
in sedimentary rock.
ITO study mountain, first see if ii
is regular, when it will be volcanic; OF
irregular, when it will probably be the
remains of wrinkle in the crust. Next
find out the material, which you can
do by examining the sides of the ra-
vines"