The Seattle post-intelligencer. [volume] (Seattle, Wash. Terr. [Wash.]) 1888-1914, 1893-10-30

trionted - 70 leave fairy good grating
Tor stock, but must hzve been a1,undantsy
covered sIfh pebbles a8d rohhlcs Arsin
it would seem irrational 10 suppose that
any conceivable sind carrert could
sculpture these mounds by erosion. There
remains no other eToding agent rus ran
ming water flowing IN some general diree-
ti0B. Hence these mounds must have
been elongated with their major ares
parallel with the dow. Currents of water
OF sufficient force 20 sweep not only the
liner matter, but 3 mass Of coarse gravel
one TO txc fees deep from between the
tunnels. yet leaving the mounds standing
as they now appear. also seem quite in
concsivshie. MAnifestiy the facts that
exist must exclude this hypothesis, rs
well as those before noticed.
In offering she following explanation of
the origin of these mounds. / would hesi-
tate to say that there can be no other way
20 account tor the phenomena. bat must
admit that can see no other which will
explain al the facts At the least, il is
earnestly hoped TO enlist sufficient Inter
est. II possible. TO lead TO . satisfactory
solution of this question
There appears 70 be sufficient evidence
70 warrant belief that during the glacial
period this region was pioughed over By
moving ice. Ii lies within the southern
edge Of the drift-bearing area. as mapped
however, would not warranSone 70 affirm
that this locality was covered BY an ice
sheet moving in the same general direc-
ton as that east Of the Rocky mountains
bat rather OF local character. similar TO
those now existing in Alaska, which start
from the crests of the mountains and dow
in all directions into the valleys and onto
thu plains below, carrying forward and
distributing the glacial drift as worn
boulders, cobbies. sand aud gravel Dur
ing and after the retirement of the glacier,
the drift was greatly modified by floods OF
water, the result of the wasting ice and
frequent rains. East of the tumuli PLAN
the land, much of which IL now under
farm cultivation, gradually rises toward
the remote mountains Wells are sunk in
this land from which to obtain water for
domestic purposes. AT the surface the
soil Is from one 20 three or more feet deep
and overiies q coarse cobble drift, which is
composed of material alike in character
with that of the mounds. The wells pass
through from SIX TO ten feet of this cobble
DRIFT TO substratn'u of finer gravel, into
which the wells extend from two TO four
feet. where permanent water is secured.
Imagine this large tumuli plain TO be
covered with q sheet OF ice reduced TO a
moderate thickness by abiation on the
border OF the retiring active glacier and
having, like the forest-coyered border of
the Malaspina ice sheet in Alaska, no mo-
ton except the gradual waste. by liguefac-
ton. However. the forces which modify
the drift are yet active, so that boulders,
cobblestones. gravel and sand are being
brought forward from the higher levels by
periodic floods. the product of accelerated
melting OF the glacier during prolonged
increased temperature. From time to
time. during the especially rapid melting
in the summers. the greater floods would
Srf1a saa MIA
along with them the smaller ooulders,
cobbles, gravel, sand and clay or finest silt
of the drift, which would be spread on the
ice surface. 1t is q well-observed fact that
coarse gravel carried on to plain by
strong flow Of water has tendency TO &C
cumuiate in masses or heaps. A slight
depression in the surface, or some obstruc-
ton, may arrest the onward movement of
q boulder or large cobblestone. while the
finer material would more or less pass on.
This boulder might stop another, and so
on, the general result being q somewhat
unequal distribution Of the drift over
the surface of the ice. The food,
as its force decreased, would manifestly
leave the whole surface more or less COW
cred with drift debris. AS the sun sends
its rays onto the drift thus distributed
with its substratum of ice. three agencies
modifying the drift claim our considera-
ton. namely, heat, grayitation and the ac-
cumulation of water in the depressions.
The thicker masses OF debris would collect
more of the heat OF y sun and this would
cause faster melting of the ice, or in
other words would make depression at
such points, into which gravitation would
carry additional drift by sliding from the
adjacent ice surface and by the washing
action of rains and streamlets.
After formulating this hypothesis in re-
gard to the tumuli of the ''mound prai-
RES" l was very much'gratified in finding
the following statements, which add
greatly to the strength OF my argument:
Prof. j. G. Russell, in has work on the
glaciers of Alaska, gives, on page 10 the
following description of lakelets on the
Malaspina glacier or ice sheet, occupying
deep, well-like depressions or pits, con-
strieted half way down, somewhat in the
shape of an hour glass. into which the
DRIFT exposed by ablation on the contigu-
Gus ice surface fails, SO that il would be
left as a mound If the ice were melted
away.
"0n the moraine-coyered portion. es-
pecialiy where plants have taken root.
there are hundreds, perhaps thousands, OF
lakelets, occupying kettle-shaped depres-
sions. Ii We should go down to the gla-
cier and examine such a lakelet near at
hand we should ind that the cliffs of ice
surrounding them are usually unsymmet-
rical, being especially steep and rugged on
one side and low or perhaps wanting en-
tirely on the other. But there is no regu-
larity in this respect; the steep slopes may
face In any direction. On bright DAYS the
encircling walls are always dripping with
water produced by the melting OF the ice;
little riils are constantly flowing down
their sides and plunging into miniature
cataracts into the lake below. The stones
at the top of the ice cliffs, belonging TO
the general sheet of debris covering the
glacier, are continually being undermined
and precipitated into the water. A curious
fact in reference TO the walls of the lake
let's Is that the melting of the Ice below
the surface IS more rapid than above.
where il is exposed TO the direct rays of
the sun. As result the depressions have
the form of an hour-gIass
Speaking of the Gsliano glacier, on page
50, Russell says:
my surprise therefore was great when.
after forcing my way through the dense
thickets, | reached the top of the hill and
found large kettie-shaped depression, the
sides of which were solid walls of ice
fifty feet high. This showed at once that
the supposed hill was really the extremity
of a glacier, long dead and deeply buried
beneath forest-coyered debris In the bot
tom of the kettle-like depression Law a
pond of muddy water, and, a. the ice cliffs
about the lakelet melted in the warm sun
light, miniature ayalanches of ice and
stones, mingled with sticks and bushes
that had been undermined. frequently
ratified down its sides and splashed into
the water below. Further examination
revealed the fact that scores Of such kettles
are scattered over the surface OF the buried
glacier"
Again, on page Ill, he says of the Hay
den glacier:
The debri. is scattered over the surface