The Stark County Democrat. [volume] (Canton, Ohio) 1833-1912, 1906-04-17
ARTIST DAME NATURE
Thacings on Rock Which Resemble
Human Work.


In the section of the National Mu-
scum devoted to geology are speci-
mems of rock surfaces curiously and
sometimes beautifully grooved and
carved. says the Philadelphia Record.
The carvings in some cases are so per-
feet as to suggest the work of skilled
artisans. AS a matter of fact, these
apparent holdings are not holdings
at all, nor are they the handiwork
OF man. They represent convulsion
OF nature at a pepiod SO remote that
there is no mode of reckoning it. In
other words, they are the rock-scor
ipgs ct the glacial invasion of the
northern part of this country.
Whether the ice came down by
land or sea, whether by glaciers creep
ing over the tace of the country, or
by icebergs and ice foes sailing ON
submergeing waters, science is unable
| TO determine. Be this as it may,
that the ice came sweeping down over
the face of the earth in huge quanti-
ties and with irresistible force these
rocks in the museum attest.
These rock-scorings are the trails
left by the ancient invader. To the
geologist their character reveals the
nature of the visitant as tracks reveal
the trackmaker. The glacialist dis
tinguishes with as much certainty the
| traces of glacier of an iceberg or
| ice foe as hunter the track OF
bear, moose, or serpent. A glacier
may be likened to prehistoric mon
ster, which leaves print of its foot
imbeded in the rock. From such slight
tokens of its some time existence
| Prof Owen builds the semblance OF
the entire animal, classes it and de-
scribes its habits.
For purposes of convenience in ge-
| ology the common term growing
| is used to describe all the effects
of the glacial invasion on rock sur
faces. Respecting their origin, gla-
| cial grooves belong to two classes,
which it is of some importance TO
| distinguish. The one class had an
| existence as grooves prior to the in
cursion of the ice, and were simply
| nodded and modified by it. The other
class owe their origin solely to gla-
cial action.
Previous to the sweeping down OF
| the ice the surface of the rock had
been subjected to various destructive
agencies, which produced great in
| equalities in it, among which were sur
| face grooves. Thus, the invading ice
| found burrows formed already. When
! these lay coincident with it course Its
| work was merely to rasp them out
and polish and striate their sides. In
their remodeled form they sometimes
| have the aspect of channels due who'll
| ly to glacial action, but the observa-
ton of the expert often discovers that
they could not have arisen solely from
| glacial abrasion. There must have
been a pre-eXistent channel to guide
and, in measure, mold to itself the
abrading ice.
A main element in the growing was
of course, iequadity in the hardness
of the rock. This finds it's simplest
| expression where beds of unequal
hardness were slightly upturned so as
to present their beveled edges to the
ice, which acted along them like a
| beading plane. In such cases the soft
beds were easily removed while the
harder ones were left standing forth
as ridges, the whole assuming a tiut-
ed surface. Grooves of this sort, which
are often to be found among the speci-
| mems of a geological collection the
unequal hardness of the rock beds
On a large scale this is thought to
have been sometimes an important
factor in determining the topography
that resulted from glaciation.
That streams of water flow beneath
| glaciers has been determined by abun-
dant observation, but except in the i'm
mediate vicinity of the ice border,
where alone observation has penetrat-
ed, the precise relations of the ice
to the stream are matters of conjec-
ture. Whether the ice continually
tends to press down upon the stream
and to force it hither and thither at
WILL or whether the stream maintains
itself by melting and wearing back
the encroaching ice as fast as it
presses up on it. and so retains
| constant channel, is unknown. 1t is
regarded as quite certain, however,
that such sub-glaciaI streams have
much abrasive power, because they
are loaded with fine, rasping glacial
sift, a most effective abrasive agency.
That they cut for themselves rock
1 - l.. T..