The Hawaiian gazette. [volume] (Honolulu [Oahu, Hawaii]) 1865-1918, 1896-08-11

some trouble with the gas. DR.. Lyons
began his lecture by saying that sort
of cram on the different kinds of rock
would be necessary. And he called at
tention TO point that he might have
missed in the previous lecture by say
ing that soil comes from rock.
There are three standpoints from
which rock may be classifed-that OF
the geologist, of the mineralogist and of
the chemist The chemist Classics by
materials into, first, silicious composed |
of silica; second, argillaceous, of al |
umina' (clay); third, calcareous, OF
lime. The mineralogist Classics by |
form into quartz, feldspar, hornblende, |
mica, calcite, gypsum. etc. Mineralogy |
is of but little use here. There is very
little Capitalization in rock. Hence it |
will be comparatively uninteresting TO
your pupils. You should have few
specimens of the most important kinds.
But where can you get them? There is
quartz in Manaohi and a place or two
on Molokai. Gypsum crystals occur oc-
casionally along the coast of Oahu. But
l have found a treasure in some rock
| ballast left behind the ice manufac-
tory. If you are really interested in
| geology, go there and get some speci-
mems, especially granite.
Granite is a compound of four kinds
of rock from the mineralogist's point of
view, quartz, feldspar, mica and horn
blende. Feldspar can be distinguished
| by its pale color and its fat, brilliant
surface, resembling mother of pearl.
II splits evenly (cleavage), and if there
are two cleayages they will be nearly al
right angles to each other. In examin
ing lava you will sometimes find crys-
| tails which you will say look like field
spar. and you will be right Feldspar
lcrystals are found in our lava. Every
one knows what mica is from seeing il
in oil stoves. etc. 1t is transparent and
easily Invisible into thin sheets. Horn
blende may be known by its dark color.
dark green. Then the quartz is what
is left II is little hard to describe il.
II is not transparent, translucent rath
er. II you can find large enough piece
ii will scratch glass, which the other in
gradients of granite viii not do. 1t is
between the other kinds and seems TO
be in a way the cement. Gypsum and
calcite are both kinds of limestone.
calcite the carbonate.
| The geologist looks TO the origin of
stone for his classification. He makes
three divisions: First, ignious, formed
by fire; second, aqueous, or better, sedi-
mentary, formed by settling as a sedi-
ment in water; and, third, metamor-
phic. i. G.. sedimentary rock which has
received its present form through the
!, action of heat, but has not wholly lost
its sedimentary characteristics.
We will consider first the sedimen-
. tary You remember that 1 described
: last night an experiment in settling
: muddy water, and the results. II left
| for half an hour only, coarse sand;
: twenty-four hours brings silt. 1 have
2 known clay TO stay in water for several
: weeks without settling. Matter thus de-
j posted in water is not yet rock in the
: usual sense of the term How does il
: get 10 be rock? 1t must be cemented in
: some way. In looking for q specimen
|. for the class 1 found this. Here the
J, professor held up a row-lock that had
: been in the water and sand till en-
: crusted with sand) The cement here
: came from the iron by the chemical
T action of the salt water. II is, however
: more frequently lime. But in mos
d cases il is not so cemented- As the clay
/. lies in the bottom of the water, il il
e buried under the sediment The weight
e seems to press the crust of the eartt
b down so that the water still covers tbs
top. Layers are thus mad-10o, 1000
:. 10000 feet deep. At the depth of Z
n mile the pressure is enormous and tbs
). temperature very much higher. Tht
e ieombined heat and pressure solidify tbs
' clay and it becomes rock once more.
81 Nine-tenths of the rock on continent
S are sedimentary. formed under water
II bat found at the top OF q mountain, per
e haps. How did it get there. The ocean
8 covered il all once. The earth was, i
+ seems certain. once molten As It cool
L ed portions of il crusted over, but tn,
: crust sank and was remelted- Afte
/, a time, however. the whole mass coole'
sufficiently so that crust could b
q formed all over the outside. This crus
u cooled more rapidly than the center a