Evening star., 1953-01-21
Sea Sediments Indicate
8 Worm Antarctic Erus
Temperate Ages Occurred
In Past 500, 900 Years
BY Thomas R. Henry

By Thomas R. Henry
The Antarctic has known at least
three temperate ages in the past half
million years.
This Is the conclusion of DR.. Jack l..
Hough of the University of Illinois.
oceanographer who accompanied the
1946-47 Byrd expedition.
Stationed on the spearheading ice
breaker Northwind as it broke through
the nearly solid 10-foot-thick ice cover
ing the Ross Sea, Dr. Hough obtained
deep cores of the sea bottom represent
ing approximately 460,0 900 years of ac-
cumulated sediments The various levels
OF these cores were dated by uranium
lead measurements and other means by
scientists of the Carnegie Institutions
geophysical laboratory.
There were alternating layers of fine
grained silt and of this same sort of silt
mixed with coarse gravel. DR.. Hough's
thesis is that the coarse gravel must
have come from the land surface of the
now completely ice-covered Antarctic
continent. All the cores were obtained
hundreds of miles from the nearest land
except for one which came from within
so miles of desolate, unapproachable
Scott Island, the black rock which
marks the beginning of the Ross Sea.
Deposited by Icebergs.
They could only have been deposited
on the sea bottom at such distances
from land, according to the thesis, by
icebergS, parts Of glaciers whose slow
flowing ice had scraped the bottom of
the south polar land for millenniums.
The upper levels of the cores, as was to
be expected. were full of the coarse ma
terial. Enormous icebergs careen in all
directions through the great ice sea.
Radioactivity measurements indicate
that this ice period extends backward
for about 5000 years. Then, quite
abruptly, the coarse material disap-
pears and the sea bottom is composed
only of the fine material which could
be found sinking to the bottom far
out at sea. This is true for about
5000 years. During this period, DR..
Hough concludes, the Ross Sea must
have been essentially free of ice At
the best, he believes, an occasional
iceberg may have drifted over the
surface of open: water.
If the sea- was ice-free there can be
a reasonable assumption that at least
the shores of the continent were bare.
There hardly could have been anything
comparable to the great ice sheet Of
the present.
$4,000 Years Ago.
There is another period of coarse
sediments from $4,000 to about 29,5OO
oil Dc
seems likely. the picture of the Ross
Sea must have been essentially the
same as now, vast desolation of ice
bergs moving slowly through a thick
sheet of solid ice.
Then, going backward, there is an
other warm period extending approxi-
mately from 10000 to 10000 years ago.
Back of that the coarse sediments
indicate long ice, age-from about
10000 to $4,000 years ago. Back of
this lies a zone OF fine sediments indi-
eating an ice-free sea from about
1873, 900 to $4,000 years ago.
From this point coarse, iceberg
carried sediments are found to the
bottom of the cores, representing about
100000 years in the past.
1t is significant, DR.. Hough points out
in report published by the Woods
Hole Oceanographic Institute with
which he was associated during the ex-
pedition, that all the cores tell the same
story. The validity of the conclusions
rests, of course. on the validity Of the
thesis.
Also Of significance, DR.. Hough says.
Is the fact that the temperate and
-ice-age periods correspond roughly to
the same glacial and inter-glacial eras
which are fairly well marked In the
Northern Hemisphere. Apparently the
ice-age history of the earth for q half
million years has been about the same
In the south as in, the north. ..
Surprising Conclusion.
The conclusion that there was an
ice-free period which ended only about
5000 years ago comes as a considerable
surprise. It has been recognized that
there must have been a time within
the last $4,000 years when the shores
Of the continent were ice-free and con-
tanned fairly high order Of plant
and animal life. This time, however.
generally has been placed several mil
lion years in the past. It is obvious
that the great ice sheet covering the
continent must have been building I'D
for hundreds Of millenniums.