Evening star. [volume] (Washington, D.C.) 1854-1972, 1952-03-31
Glucier Retreat Began
About ! | 500 Years AGO
Rudiocurbon Yurdstick Gauges
Age Of lce-Ase Peat Boqs
By Thomcs I. Henry

- - ss~sssesS Ne ttSUJY
The glaciers Of the last great ice are
IN the northern hemisphere began their
retreat about 1850 years 40, -
Their withdrawal northward rec,,,ras
about 5000 years. The more they rneitsS
the higher rose the sea level from the
melting ice and the debris from ~
continent deposited on the sea bottoms.
This conclusion Is reached by the new
radiocarbon measurements Of ancient
cedar forest and peat boys Of what was
group Of islands on the Atlantic coast
apparently covered q much larger land
area at the height Of the glaciatiOn.
This was progressively submerged by
the rising sea as the ice sheet melted.
The measurements have just been
reported to the American Association
Tor the Advancement of Science here
BY DrS. j. Laurence Kulp, Herbert w.
Felly and Lansing e. Tryon Of Columbia
University.
Radio Carbon Measuring Stick.
Carbon IA. the Exploding form" OF
this element which Is constantly being
created In the high atmosphere by the
transmutation Of nitrogen under cosrnic
ray bombardment. forms part Of the
substance of all living things. It occurs
IN ratio OF about one part to thou
sand Of ordinary carbon. It has q half
life Of approximately 5.568 years. That
Is. half OF the element originally pres
emit IN an object which has reached
the end Of its growth disappears. In
another $3.50 years half OF the re-
mainder disintegrates, and so on until
essentially none is left. The amount
which can be measured indicates the
age Of the object-up to about $4,000
years when the exploding atoms are SO
few they hardly can be Disseminated.
The Columbia investigators deter
mined In this way the age Of fossil
cedar logs dredged from the entrance
to st. Georges Harbor in Bermuda.
which lay under 10 to 20 feet Of water
and to 10 feet of mud. The evidence
was clear that they formed part Of q
great cedar forest, of the same type
as the Bermuda cedars of today, which
once covered this hypothetical greater
Bermuda" First came the silt washed
down from the Appalachian foothills.
This probably killed the forest. Then.
inch by. inch, the rising sea sub
merged 1t.
The age Of the logs was determined to
be between 1850 and l1,7O0 years.
This represents about the date Of the
death Of the trees. They also measured
samples Of peat obtained from the same
dredging, but considerably above the
logs. These show ages ranging from
$500 to 1900 years. The vegetation
which formed this peat apparently grew
after the land was swampy but before
1t was submerged.
The time of the retreat Of the last
phase Of the so-called wisconsin glaci-
alton" which apparently covered good
deal OF the northern hemisphere now
can be calculated, DR.. Kulp and his
associates report, on three independent
radio-carbon measurements. AL are in
substantial agreement. One was made
on material associated with the glaci-
alton near Mankata, Wisconsin. and
the other on mud from Irish peat boys.
Magyar Altar 1,470 Years Old.
They also report measurements Of
wood from carved Magyar altar at the
ruins Of Tekel, Guatemala, which give
an age of about 1.47O years-in close
agreement with calculations made on
other grounds that these ruins date from
about the fifth century.
The Columbia workers have taken the
first steps. they report, on technique
which may prove Of great value to
oceanographers. The amounts Of carbon
dioxide dissolved in different strata Of
ocean water show minute differences.
All this carbon dioxide contains its due
proportion Of the radioactive carbon.
BY means Of their technique, they be-
heve, it eventually will be possible to
trace various underwater currents-su
as the surface water Of the Arctic which
sinks under the Atlantic and proceeds
southwark along the sea bottom. This
water. obtained by deep sea sampling.
can be differentiated from the normal
surface Atlantic water.
Measurements In the future may
show. they say. how far this Arctic water
proceeds towards the equator.