Ashland tidings. [volume] (Ashland, Or.) 1876-1919, 1913-05-05

ume of the cavity from whose depths
it arose, was formed. The phenom-
enon which resembles the great pitt
ted craters of the moon seems to be
of recent date, so fresh is the lava
and so symmetrical is the cinder
cone. The giant frs which cover the
base of the cone have not as yet had
time to take possession OF it's sum-
nit.
This succession of geologic events
is so indisputably imprinted on the
rocks that the Portland Alpine Club,
at meeting held on the rim of Cra-
ter lake in 1896, did not hesitate in
giving to the giant cone, which has
disappeared, the name of Mount Ma
zama. Geologic examination has
only confirmed the rather instructive
impression as to the true nature of
the crater. But at what epoch did
/ the cataclysm occur, which caused
the ancient cone to disappear? And
what force of nature was employed
in replacing a giant cone by the
great abyss which we see today? 1t
is concerning this dual question
which we wish to speak.
First, what were the dimensions
of Mount Mazama at the time of it's
greatest splendor? Mr.. Diller states
that at an elevation of about 2,44O
meters the actual diameter of Crater
lake is about the same as Mount
Shasta, California, a volcano whose
lavas are analogous as to the degree
of fluidity. Shasta rises TO an ele-
vation of 1850 meters above this
level and has an altitude of 4,3S3
meters. Mount Mazama must have
been at least as high, and this is
PshUwn by extending the exterior
slopes about Crater lake to a COM
mon origin which would be the sum-
nit of the original cone. One may
imagine the primitive magnificence
of this mountain by noting today the
absence of the enormous amount of
material which once formed it's mass.
The caldera has a volume of twelve
cubic miles, while the cone, which no
longer exists, had volume of five
cubic miles.
But how could such an imposing
mass-Mount Mazama, one of the
largest pillars of the Cascade range
have disappeared without leaving
any trace? If the mountain was
blown off by sudden and terrible
explosion, where, then, is all the de-
bris? Or were the burning lavas
drawn downward through some sub
} terranean passage; were the lavas
suddenly sucked into the chimney of
the cone, thus taking away the sup
port from the superstructure and
permitting it to fall in and become
, engulfed? These two hypotheses,
, that of an explosion and that of an
engulfment, have often been given to
explain the formation of large era
} ters and crater lakes. Doubtless,
: these hypothesis have their applica-
, ton, depending upon this or that
particular case; however, neither one
seems to be sufficient to fully ex-
| plain Crater lake. But there is little
/ doubt as to the true cause. The hy-
, pothesis of an engulfment alone
seems to explain, when due consider
| alton is given the observed facts. If
! the hypothesis of an explosion were
7 accepted, where is all the volcanic
7 material which would have been
, thrown out upon the surrounding
l country by this great American Kra-
3 katoa? In vain do we search for a
= trace of it. Everywhere we see only
: the normal strata and lava flows
, with here and there some beds OF
S pumice which are of little impor-
r tance. The last coverings or strata
a of the cone, as we have already SEEN
/ were formed by dacites and basalts
: which have nothing in common, Sc
far as their mineral nature is con-
9 cerned, with the andesites which rep
g resent the principal mass of the vol
! cano.
n AS the divergent striae (Which
g may be observed at a number Of
h points around the periphery of the
s caldera) indicate, Mount Mazams
e must have been center of important
: glacial dispersion during the pleis
Il tocene period, and this is a point O.
= great Importance in the chronolog!
of the volcano. The last eruption
e dacites which are superposed abov,
st the moraines, to, the northeast o
n Crater lake, must have been contem
3. porary with the final catastrophe
II for these lavas were still sufficient.
l. plastic when the cone was replaced
l. by the caldera, to change their angl
n of inclination, as one may see toda
D. in the cliffs of Fleetwood Cove.
Ie The waters which fill Crater lax