The Corvallis gazette. [volume] (Corvallis, Or.) 1862-1899, 1893-10-27

The loan is 1ightish yellow or buff,
though shade darker and heavier than
similar material in Nebraska Among
the large blocks or boulders we have
granite, porphyry, quartzite grey, light
and dark red and purp1ish, with heavy
deposits of slate rock. In some of these
deposits more beautiful and valuable
stone is found such as Jumps of ribbed
chalcedony and richly variegated green
stones may be gathered.
A Nebraska Field.
For the purpose of getting more cor
rect understanding of the drift deposits
we gather from another field the po
sition of the several varieties of material
as they were deposited and which, in
general character, will obtain through
out the period.
In eastern Nebraska upon the Gre
taceous floor drift material is found rest
ing thereon amounting to eighty or one
hundred feet in depth as follows: At
the base, hard and tough variegated
clay in which is slightly mingled gravel
and boulders. Upon this clay is found
bed of fine quartz gravel about two
feet deep, size of gravel little less than
one quarter inch cube. and each grain or
gravel apparently of the same size and
weight, showing that not only this bed
but beds above were conveyed by water
and that the determining cause of deposit
at that place was the strength of the cur
rent at the time and size Or weight of
pebble.
Above the quartz gravel is a bed of
coarse, rusty sand followed by less
coarse bed of clean grain, topped with a
bed of sand of finest particles: Each of
these beds is we'll defined by clear
level ines.running across the face of de-
posit. Upon this bed of fine sand rests
the rich buff loan to depth of seventy
five feet Or more. While, this loan varies
in shade or color "a little, there is small
difference from top to bottom in quality
as to fineness or..richness. Not pebble
the size of pea is found in it and though
we travel scores of miles, excepting in
the bed of the deep ravines, which time
has cut through and down to the boulder
clay, not stone is to be found. One ex-
ception to this rule was found in this
field but it was the only one known to
the writer as follows: In one of those
ravines and near the top Of the sloping
bank a large slab of red quartzite lay
with few small pieces, corners straight
and sharp as when river. from its native
bed. This slab as it lay was sloping
with the bank and evidently when de-
posted had been upon--the surface of the
loan after it had become hard enough to
sustain its weight; subsequent erosion
forming the ravine had permitted its
sliding from its original position. From
the above we gather the method of the
various deposits of the drift. First,
boulder clay, second, very fine gravel,
followed by beds each one finer than the
preceding till we. reach the top, when it
is capped by large and small angular
rock belonging to the earliest of days.
Each one of those beds gave indication
that there was time between each de-
posit that is, each one had become set
tied so that subsequent deposit rested
fairly upon the bed Immediately beneath
it, and without mixing with each other.
sN In The Valley. - .e
While we have not the number or
variety of drift deposits as mentioned
above, what we have will be found to
have been deposited in the same order.
Here we have as yet seen no boulder clay
but we have in its place much heavier
deposit of gravel resting upon Eocene
strata. This gravel is found in the bed
of the Willamette river. It is covered by
loan and soil in the valley near Corvallis
about twenty feet. Fifteen miles south
it comes to the surface and covers many
acres of land. The same gravel is used
for our streets and roads instead of broken
rock. Where the gravel is covered by a
subsequent deposit of sufficient depth it
will be found to be loan, topped with
darker soil. .~Eas -2e y st"
But if we are short of the variety of de-
posts, as in the Nebraska field, our blocks
or boulders make up for this largely, for
here they are strewn along for miles near
the base of the foot hills and frequently
stretching out one or two miles into the
valley; where the center of wave-ike
undu1ation occurs, these bou1ders will be
scattered, and where the road passes over
them they form hard grey pavement.
RARY pIINNINc cnRE