The Corvallis gazette. [volume] (Corvallis, Or.) 1862-1899, 1893-10-27
THE OLDER COAST RANGES.
With More Recent Geological
Formations in Benton
County.
BY JOHN RAY.
[Continued from Last Week.

have seen them. A few further points
may be suggested. Taking the Vine
yard-Kings Valley ranges, they stand
quite apart from more recent formations.
An excellent example is found in the
Osburn hill, where, standing alone, its
base runs sweeping out as the oak, where
it sinks under the base of a low Eocene
hill.
1t is, too, at this junction of the older
and more recent formations where so
much igneous action has taken place.
Where it runs entirely around the Oldest
system, up the fanks considerably, and
also where recent formations are some
what contiguous, they. have met the same
fate. How near the Miocene comes to
the older formation we do not know
exactly, but from Summit to Yaquina
there is comparatively little igneous
action visible. There is dixie going up
to Rock Creek, there..is-another at Pho
neer, little horizontal intrusion in the
sha1es about Porter's, but as compared
with the older formations it is as nothing.
Then, again, its schistose trap taken from
those places bear no resemblance to simi-
lar material east. It is like its hills, very
common.
There is, too, every reason to believe
that the metamorphism, such as it is, in
the Kings Valley ield,..took place prior
to the igneous operations subsequent to
the rise of the Eocene deposits. Where
this action has taken place it has been
violent but the quiet and easy change
in the flags and shales of the older rocks
does not exhibit this violence. Then
again, with the exception of the little
strata remaining upon the tfanks of the
older hills, they seem to be solid body
of metamorphic rock, and further, that
the material with which this strata at the
base is composed, is from the debris of
the older strata above, breccia, flag and
shale show this in a new arrangement
of older material, andin the coarseness of
grain not found in more recent or distant
deposits. .....
Another feature in the Kings Valley
field is when the sediment composing the
strata at the base of the hill was deposited
it must have been in fresh water, for
there is no sign of marine life. There
is leaf or two and creeping things have
left portions of their bodies, birds and
small animals their footprints upon the
soft shale. The more curious too, it is,
when we remember the west face stands
overlooking the Pacific Ocean. But
when we look at the deposits of the
Eocene as well as Miocene which have
been laid down and largely from this
older land, we may try to imagine if we
can the former greatness of this formation
and the great change which must have
taken place, but all we can now find or
see is the skeleton of what was. t 7..
At the Vineyard field, things seem
more natural and with the opening in
the range previously mentioned the sea
could sweep in, up and down the valley,
the bed of mari deposited and molus-
can life in highest enjoyment in the
shelter there existing. r t
In a bulletin published by the Geo1og-
ical survey, Washington, 1886, "Notes on
the Geology of Northern California, " by
I. S. Diller, who says, '"The distribution
of the rocks of the Chico group clearly
indicates that during the Chico epoch
the northwestern portion of California,
with the adjacent part of Oregon, em-
bracing the Trinity, Salmon, Scott, Sis
kiyou and other mountain ranges of the
Coast Range, was large island, sepa-
rated from the still larger continental
land mass of the same strata in the
Great Basin and Sierra region by wide
strait now bridged over by the Lassen's
Peak volcanic RIDGE" and again,
South of the Rogue river valley the
cretacean island lay completely west of
the position now occupied by the Cas-
cade Range. To the northward its ex-
tension is but partially known e
The heavy body of black clay men,
toned on the Foster place is just such
material as is found in the marsh land by
Toledo. The fossil wood and Terredos
with Corbiculas just obove and the fossil
ostrea in the higher sandy clay stone
show the estuarine conditions. Higher
in the formation Zirphaia was obtained
with other fossils unlike those found near
Corvallis. With condition such as we
have here, viz. brackish water, land must
have been to the west of it to furnish
fresh water sufficient to modify the briny
water. from the ocean. Giving us this
barrier to the ocean, the older Coast
Ranges, this condition is met and cannot
be met otherwise, for up to this time the
Miocene uplift had nostaken place. -
e Another problem also seems to be
solved, namely, why or how it is that at
distance of ten miles or more from
Corvallis, strata of a lower horizon is
founds The opening in the old Coast
Range at Phi1omath permitting the tidal
waters of the ocean to come in, we find
5riof,t oocf of ft,;o Gcotf,e hill ;~, +1,.