Evening star., 1954-04-14
Alaska Husn't t Always
Been as Chilly as Now
Could Have Been Winter
Resort 1900 Years Ago
By Thomos R. Henry

There was a warm interlude Of at
least $4,000 years in Alaska's history.
1t was during this period, when the
center of the great peninsula was COW
cred with game-f1lled forests. that the
human race may have obtained its
first foothold in North America.
This period started about 10000 and
ended about 10000 years ago. according
To dates established by the new radio
carbon method of determining ages Of
organic deposits. It came during the
so-called Wisconsin glaciations the
last of the great ice ages.
Such is the picture presented by DR..
Troy l.. Pewe of the United States Geo.
logical Survey in report to the Alaska
Science Conference. The warm inter-
lude, DR.. Pewe's studies show, followed
a long cold period during which much
debris was deposited by glaciers and
great ice wedges formed in the earth.
Buried Bones 0f Mammoths.
But starting about 10000 years ago.
he says, "the valleys were sporadically
filled with muck that contained buried
trees, bones of extinct mammoth. mas
todon, horse. bison and other animals,
and a few partial carcasses of extinct
mammals. Plant fossils, however. re-
veal no species different from those in
central Alaska today. Perhaps this
interglacial interval was warmer and
longer than the interval since the last
major glaciation and was favorable
time for the existence of man in
Alaska.
Evidence from central Alaska re-
veals that the extinct mammals not
only lived until fairly recently but ap-
parently lived in abundance during
both glacial and interglacial periods"
This later finding, he says. is quite
contrary to the common idea that ami
mails of the interglacial periods were
killed off by the coming of cold. They
may not have been quite as abundant.
however, after the warm interlude.
Still, he says, both horses and bison
have been reintroduced and now live
wild in central Alaska where winter
temperatures 60 down below 10 F.
Some carcasses buried in the muck.
he says. were preserved for long time
in the cold, damp, organic silt before
they were permanently frozen. The
period of deep freezing which formed
the permafrost and ice wedges present
today is believed to have started less
than $4,000 years ago and probably in
dicates the time of the last great glacial
advances.
Climatic Variations.
During the last 10000 years. DR..
Pewe says, there have been several
O1i iV,oo iof
indicated by fluctuations of the glaciers,
thawing and refreeZing of sediments,
disturbance of sediments and advances
and retreats of tree lines. There was
warm, dry period from $500 to 1000
years ago, followed by a colder and per-
haps wetter period which reached it's
climax from 200 to 400 years ago. Since
then there are been slight. but gen.
orally progressive, increase in tempera-
ture.
During the warm period permafroSt
was thawed to a depth of several feet
and much muck was deposited No re-
mains Of extinct animals have been
found in this muck. Buried trees, how
ever, indicate that forests were consid-
erably more extensive $500 years ago
than today. Especially in southeastern
Alaska they f1ourished in areas now
covered, or only recently uncovered. by
ice. Glaciers receded to points con-
siderably behind their present fronts.
Then came the so-called little ice
age" from which North America seems
to be just emerging Glaciers through
out Alaska underwent their greatest
expansion since the last major glacia-
ton.