The San Francisco call., 1903-12-22

Man and the Glacial Period. Etc-1
.tCoryrtght 1903. icy Joseph i. Bowles)
The story Of the glacial period has
not yet been half told. Its wonders
are increasing every day. 1t is the
last Of the great geological epochs, and
has not vet passed away. Greenland
is stiu shivering under the rigors Of
glacial conditions. With the eXcep-
ton Of a narrow belt Of mountains
around the southern end, the whole
continent. some 100000 square miles
in extent. is sum buried beneath ice
from one mile TO two miles deep, while
the Antarctic continent. with a still
greater area. is so completely en-
veloped in ice that explorers have yet
been able TO penetrate only the merest
fringe at two or three points.
But during the glacial period proper
the ice TO depth Of more than a mile
covered 100000 square miles of
North America and 100000 square
miles in Europe. In North America
the southern border Of this ice field
England coast. rising like q great ice
wall out Of the water. and westward
10 q line running through Long Island,
across New Jersey and Pennsylvania
TO Salamanca, y. Y, where ii turned
sOuthWestward and, with many minor
variations, reached the Ohio River
fifty or sixty miles above Cincinnati,
crossed Kentucky and Southern In
diana. reaching its farthest extent at
Carbondale. III, thence, bending
northwest. il crossed the Mississippi
River at ST. Louis. and followed the
Missouri and Kansas rivers to Topeka,
where il swung nOrthward across the
eastern parts Of Kansas and Nebraska,
and through Central Dakota to near
the Canada line; thence proceeding
with a long loop where it crossed the
Rocky Mountains and the Sierras) 60
Puget sound and the Pacific Ocean.
II one had approached this line dur
ing the glacial period anywhere from
the south he would have Immediately
struck the conditions Of Greenland
and found them continuous for thou
sands Of miles. Alaska still retains
the stumps Of this great glacier, sew
eraI hundred square miles being cover
ed by the Muir glacier alone, and a
still larger area by the Malaspina
glacier. which comes down from
Mount St Elias. In Europe the ice
fields radiated from the Scandinavian
peninsula. extending across the North
Sea to Southern England, and across
the Baltic 10 Central Germany and
Southeastern Russia.
In thinking Of the glacial period il
should be kept clearly in mind that
glacial ice is simply compressed snow
Glaciers are formed wherever there is
a snowfall which exceeds the melting
power Of the warm season. Every one
is familiar with the fact that a snow
ball may be made as hard as ice by
sufficient pressure in the hands. Where
snow accumulates its own weight pro-
duces the necessary pressure ana trans
forms the lower strata into ice.
That ice in great masses could flow
ike cold tar or molasses or any other
semi-fuid seemed, until a short time
ago. impossible, and did not enter into
the thought Of mankind. But about
scventy years ago il was demonstrated
in Switzerland that the ice WAS actually
moving down the valleys, proceeding
not like an avalanche but creeping
with a true flow and carrying on its
back and frozen into its mass frag-
ments Of rock Of varying sizes, some OF
them being as large as a small house
Under the lee Of one Of these rock
masses on top Of the Aar glacier Agas-
siz built him a hut and conducted many
Of his most important observations.
The great extent Of this glacial move
ment in former times was shown by
the distance (which some of these
powders had been carried. Many
large masses Of rock from Mont Blanc
were found more than a hundred mile.
away on the hanks Of the Jura Noun
tains, which border the opposite sid,
OF the main valley OF Switzerland
Bowlders from the same region wer,
carried as far east as Zurich, and al
far west as Lyons in France. and ar,
sprinkled freely over the east coast o
England, nearly as far inland as Lon
don.
In North America the transportation
Of bo=vlders by glacial ice has beer
wen more remarkable. The backbon'
Of Cape Cod and Long island, a lin,
Of hills from one hundred to two hun
dred feet high, and two or three mile
broad. is simply pile Of powders anC
small fragments transported from New
England and Canada. Plymouth Rocl
is q glacial bowlder which journeyet
from it's northern home thousands o
years before the Pilgrims set cut from
Holland Bowlders from the Adiron
dack Mountains are found upon tn
SUBMITS OF the Alleghenfes ia North
eastern Pennsylvania. In Southern
Ohio there are long belts Of CANADIAN
powders which can be traced to ledge
Of rock north Of Lake Huron. Even il
Boone County. kentucky, a few mile
south of Cincinnati, a number of re
sasper conglOmerate powders some o
them two or three feet in diameter
have been found. which came fror
well-known ledges in Canada north o
Lake Huron. BoWlders' Of large siz