The San Francisco call., 1903-12-22
INSTRUCTIVE CTUDEC
BY lNOIEDHAA1AE2lN. AND
ukESS)FIEN

found as Tar southwest as hcOkuK, Ia.
Armed with these facts concerning
the former extent of the Swiss glaciers.
Agassiz went to Great Britain and
came to America and initiated those in
vestigations which have shown the
spread Of glacial ice over the areas al
ready mentioned. Scandinavian bowld-
ers cover Northern Germany, and are
found 700 miles southeast at Kief, Rus
sia: found at Tuscumbia, sixty miles
up the Usage River, which comes down
from the Ozark uDlift TO the south.
They are also found on the south side
Of the Kansas River as far west as
Lawrence and Topeka, while windrows
Of them are found in Central Dakota,
which have been derived from lodges in
the vicinity of Lake Superior.
The size of these ice-transported
powders is certainly surprising Sew
eral in Switzerland which have been
moved more than 100 miles would
weigh more than 1000 tons apiece The
celebrated Pierre-a-Bot. a bOwlder
above Neufchatel, Switzerland, meas
ured 80 by 20 by 40 feet, containing
about 10000 cubic feet, while another
near MOnthey contained more than Co.
600 cubic feet. Ship Rock, near Pea
body. Mass, is a glacially transported
bOwlder estimated to weigh 100 tons,
while Mohegan Rock, in Montville,
Conn, near Norwich, would weigh TO-,
600 tons. At Madison, n. H., there is a
bowlder measuring 30 by 40 by 75 feet,
which can be traced to ledges of Con-
way granite. about two miles away.
The so-called Judges Cave, or West
Rock, near New Haven, Conn, is
formed by a transported bOwlder weigh
ing 100 tons, which can be traced to
well-known dykes of trap sixteen miles
TO the north. A granite bowlder near
Lebanon, Ohio, which was brought by
the ice from Canada, measured II by 13
feet, with eight feet out of ground, and
evidently a much larger mass under
the ground. But Professor Orton has
described a mass of Clinton limestone
in Freeport Warren County, Ohio,
which is three-fourths of an acre in
area and sixteen feet in thickness,
which has been brought several miles.
The central part Of Northern Iowa con-
tains a great number of powders of
exceptional size brought from several
. LullAAA GU lllllES dM MdS- OllG VI lttIll Iul
nished building stone enough to con-
struct an entire church.
Although these transported powders
are such striking witnesses to the slow
but majestic movement of glacial ice
during the glacial period, they are by
no means the only ones. AS the ice
slowly crept over the surface fragments
Of rock became frozen into its lower
strata, and powders, gravel, sand and
clay were dragged along beneath it,
furrOwing and scratching and polishing
the surface of the rock to an aston
/ ishing degree. Almost anywhere over
( this glaciated area the removal of the
soil viii reveal scratched and polished
rocks underneath. The direction Of the
/ scratches and the grooves shows the
direction in which the ice was moving
at the time they were made. This was,
in the main, outward, toward the mar
/ gin of the glaciated area which we
+ have described, but they We're many
curious variations. In Central Ohio the
direction Of the glacial scratches is
southwest, whereas on the islands in
/ the western part Of Lake Erie it is
,
/ extensive grooves and scratches have
+ been found where the movement is to-
ward the north. This variation in the
direction of the grooves and scratches
/ indicates that there were eddies in the
! ice, such as are found in the current
( Of a deep, slow moving stream of wa
/ ter. The grooves on the islands in the
western end CT Lake Erie are among
/ the most remarkable in the world. One
I groove, in hard corniferous limestone,
was about twenty feet broad and eight
/ feet deep, extending for a long distance
I across Kelley Island. The surface of
I this groove is most finely polished, cor
ais and other fossils being cut off as
sharply as could be done by any grav-
I er's tool. The direction of these grooves
in the bed of Lake Erie is evidently
due to the fact that the depression of
the lake diver ted the ice movement in
its closing stages in the direction of its
longer diameter toward the natural out
let on the west.