The Hawaiian gazette., 1894-01-16

lava streams, IT'S ejecta of scoriaceous
lava, and even of lava bombs lying
still where they fell, is found in Tele-
graph Hill.
Diamond Head is beautiful spe
cimen of a tufs cone, pure and sim
pie; Punchbowl of tufa cone which
ended in election of molten lava, in
sufficient to form any stream, al
though several miniature assures
opened in its sides, leaving beautiful
examples of eruptive dykes. Tan
talus, Sugar-loaf and Round-top, as
we'll as gravel beds, to leeward OF
them, illustrate the results of explo-
sive eruptions.
The ridges separating Pauoa and
Nuuanu, Nuuanu and Kalihi, or
Manoa and Palolo, illustrate the
extreme effects of erosion in dissect.
ing a volcanic mountain, while, in
contrast, the ridges between Pauoa
and Manoa show their angular out
lines softened by the covering OF
volcanic sand that has been sifted
over them from Tantalus.
The filling up of the upper parts
of Makiki and Pauoa has given Us
also in these valleys picturesque
waterfalls and gorges.
Streams diverted from their course
by obstructing lava flows ere seen in
those issuing respectively from Ma.
noa and Palolo, crowded close to
gether by encroaching lava from
Rocky Hill on one side and Tele-
graph Hill on the other. Makiki
stream, after having been damned
up by volcanic gravel, has had to
form for itself a new channel, giving
US thus a pretty illustration of the
action of water on comparatively
level ground consisting of loose ma
terisl. The example of the Moanalus
stream in cutting through obstruet-
ing tufa is most interesting of all.
Effects of hot springs, charged
with calcareous matter, are seen on
Diamond Head and in connection
with other tufa cones, as also in Ma
kiki valley.
The prolonged action of heat from
the molten lava of Punchbowl has
resulted in giving the tufa of that
cone a remarkable semi-crystalline
character from capitalization of car
Donate of calcium.
Wind drifted sand has accumu-
lated at the base of Diamond
Head. The action of the sea has
formed also at the base of that cone
bluffs, now removed short distance
from shore by elevation OF the land.
Other evidence of a change of level
in the land Tor of the sesl, is seen in
the reef formations which crop out
in Honolulu, on Prison island aud
throughout the Moiliili region.
OF course the coast is fringed ev-
erywhere with living reefs, the en-
trance to Honolulu harbor illustrat-
ing the effect Oh living coral polyps of
water from mountain stream.
Sandstone, formed from shell and
coral sand, and conglomerate, or
breccia, from tufa fragments or from
tufa, lava and coral fragments mixed,
are among the interesting formations
at the base of Diamond Head, where
also may be seen illustrations of the
formation of pot holes and parallel
groovings, and other exceptional
effects of the action OF sea waves.
The capricious behavior of tidal cur
rents has been recently illustrated to
the cost of property owners along the
Waikiki beach.
Deposits of oxide of manganese,
forming crust on rocks that have
been submerged, are not rare, especi-
ally about the base of Telegraph Hill.
A crust of the same material covering
the surface of some of the tufa or the
northeast slope of Diamond Head
seems rather to have been deposited
from flowing water, although the re
gion may once have been submerged.
The lava of the Moiliili quarry, which
seems to have flowed over coral, and
probably at a recent period, is dis
tinctly smygdsloidal, the result, 1
think, of submergence.
1 have drawn roughly a geo
logical map of Honolulu, recog
nizing the following superficial
formations: l. The original lava
of the dissected mountain
mass, in the ridges separating the
great valleys 2. Low land with a
soil consisting of ancient decomposed
lava 1.-THE Palama region). 3. Allu-
vial deposits from Nuuanu and IA
lihi streams. 4. Tufa of Punchbowl.
5. Volcanic sand in stu from the Ma
kiki group of crsters. 6. Gravelly
soil consisting mainly of decomposed
volcanic sand of No. 5, covering much
Of the plain and extending into Nuu-
anu Valley. Z. Scoria and lava from
Rocky Hill, which seems to extend as
far as the Moiliili quarry. s. Lsva
from Telegraph Hill. 9. Out crop
ping reef rock in Honolulu. Moiliili
and makai of Pslama. 10. Sand and
other coast formations OF Kakaako
and Waikiki. / have not yet sccur-
ately determined the limits of these
several areas; the map shows rather
work laid out to be done than what
has been actually accomplished. 1
shall try To oct helm in carving IL