The Hawaiian star. [volume] (Honolulu [Oahu]) 1893-1912, 1900-07-20
ABOUT HITCHCOCK'S GEOLOGY
OF OAHU"
DR.. S. E. Bishop Says Pela Paha! Pos
sibly so-Antagonizes the Theory of
Calcareous Origin Of Volcanoes.

EDITOR STAR-The contribution to
our knowledge of this Island is unques-
tionably very valuable one, which Is
made by Prof G, IL. Hitchcock in his
pamphlet of 40 pages, published as "a
Bulletin of the Geological Society of
America The last three pages are
Notes on the Tertiary Geology of
Oahu" by w. H. Dali. DR.. Hitchcock
occupied considerable portions of 1883
and 1889 in observing the geology of
this Island, especially along the rail-
way, in the secondary craters, and on
the Nuuanu Pail. Without any pro-
fessional experiences, having only a long
local familiarity with the phenomena
discussed, l incline to regard his OBJ
servations as accurate and acute, and
his conclusions based upon them as
mainly sound.
l desire here, however, to express dis
sent to certain points made by the
! learned geologist.
! DR.. Hitchcock, on page 81, seems SUBJ
stantially to adopt what l presume is
the theory Of Alex. Agassiz, that vol
| canic activity starts from extensive ter
tiary deposits, so that thick limestone
! aCcumulationS underlie tie ... ,untains
! of Oahu. This seems to / purely hy-
| pothetical, and without Foundation be-
| yond Agassiz' theory that vast masses
! of limestone accumulate in the bed of
the ocean, and their weight so disturbs
the earth's crust as to engender assures
through which volcanic eruptions es-
cape.
l think the evidence is against the
existence of limestone beds underlying
any of these Islands. The limestone is
| apparently all confined to fringing coral
reefs. 1t is characteristic of the Sec
ondary craters fringing the shores of
Oahu, among their ejecta to have dis
| charged great quantities of calcareous
matter, including coral and shells,
which are found imbedded in the tufas
| discharged. DIR. Hitchcock specifies
many instances of this fact. But to the
| best OF my knowledge no calcareous
matter whatever is discharged from in
| terror craters like Tantalus, or the one
| in Luakaha. If the vents of those era
| ters came through limestone beds three
or four miles underneath, surely some
! fragments of the limestone would have
| been torn off and brought to the sur
! face, as was done by Diamond Head
and KOko Head craters.
| | have never seen a trace of calcar-
eouS matter in any of the older lavas
of our mountains, which must have
! torn their way up through those imag-
! ined limestone beds, if such existed. In
July, 1887, at Kilauea, in company with
! DR.. ]. T. Dana, we carefully scrutln-
! lied the rocky ejecta of the great ex-
| plOsion of 1890. These covered a vast
| area with great variety of stones torn
from the bowels of the earth. We GER
| tainly never noticed a single calcareous
/ specimen among them.
! l especially object to Mr. Dall's con
Eclusion that Diamond Head was thrown
! up in the very ancient Pliocene period.
! This crater evidently belongs to a very
recent period, though older than the
| koko Heads, which are but slightly
| tluted by rain erosion. Dali even tries
| to prove the very modern material of
| "a
! that the contained shells of Conus and
| Purpura were not lat present repre-
scented on the ancient beaches" page
| SD, whereas those shells are among our
most common living species.
He also tries to make out that the
Achatinellidae Gland shells) found in
the brecca at the foot of Diamond
Head are ancient types, whereas Dr. ].
| T. Gulick page 54) found no essential
variation i'm them from present species.
He says, The conclusion to which
came was that the whole mass of Dia-
mond Head had been slowly deposited
in comparatively shallow water, and
gradually elevated without being sub
! jected to notable fieXure. The election
of material at first must have been in
termittent, with long quiescent periods,
to enable the shore to have been re-
populated with mollusks and corals."
Mr.. Dali evidently has no conception
of the process of formation of a tufa-
cone, which is rapid, not slow. The
tufa is driven high into the air i'm the
form of hot mud which falls in vast
I showers around the vent, building up a
ring of soft laminated rock. If the fall
had been intermittent, with "lOng quies-
cent periods intervening, that would
be evidenced by layers of soil interposed
| between the strata or laminae of tufa
| which is not the case.
1 am not able to offer any definite OBJ
lection to Mr.. Dalrs reference of the
Pearl river fossil strata with their eX-
tinct shells to the pliocene. The noun
tains of Oahu, as proved by their i'm
mense subaerial erosions, are very an
Client. Dali goes so far as to say ut is
probable that Oahu was land, inhabited
by animals, as early as the Eocene."
Pela paha! Possibly so.
S. f. BISHOP.