Evening star., 1954-10-18
Rodiooctiyity Reveals
Age Of Materials
New Study Gives Experts
Better Picture Of Nctura
BY Thomos r. Henry

The last major glacial advance Ia
North America was about 10000 years
ago. Between $4,000 and 10000 years
ago it had reached as far south as
central Illinois.
Neanderthal man. the grotesque.
beetle -browed human-like creature who
is supposed.to have been modern mans
direct predecessor on earth, probably
still was extant IN North Africa $4,000
years ago.
The oceans were considerably warmer
three or four centuries ago than at
present.
These are some Of the conclusions
DR.. Hans E. Suess Of the United States
Geological Survey has made from an
extensive series of age determinations
OF biological materials, based on the
radioactive carbon they contain, The
determinations were carried out by a
new and presumably more accurate
method than has been used in the past,
and which was developed by Survey
scientists.
Constantly Produced.
A radioactive isotope of carbon,
major element Of living things, con-
stantly is being produced by the trans
mutation of nitrogen by cosmic ray
bombardment in the upper atmosphere.
It is mixed with the whole atmosphere,
is utilized by plants through the process
Of photosynthesis. and enters into the
bodies Of animals which eat the plants,
or eat other animals which are plant
eaters. There is constant balance
between the amount of radioactive
carbon and ordinary carbon In the
atmosphere. and hence in the tissues
OF all living things. This carbon has
half -life-that is, period in which
half Of any amount originally present
win disintegrate-of about 5000 years.
The amount present in any organic
remains indicates roughly-perhaps In
terms Of centuries-the age Of the
material.
DR.. Suess was concerned primarily
in fixing date for the last great gla-
cial advance. This has been estimated
at from 10000 to 10000 years ago, but
previous methods have not permitted
much closer estimate. The Geological
Survey scientists determinations are
based on the age determined for or
ganic remains, such as tree trunks and
peat. which undoubtedly were in the
path OF the glaciation. During the past
20 centuries there has been notable
retreat of the ice, interrupted by sew
eral advances. Some hold that the
Northern Hemisphere is still in the last
ice age.
Charcoal Findings Important.
Perhaps the most important of all
the findings is that of the age of char
coal from the Haua Fteah cave in
Tripoli. This charcoal is associated
with a jaw of Neanderthal man and
presumably is remnant of his hearth
fire. The radioactive carbon determine
ton probably provides the most exact
date yet calculated for the survival Of
this grotesque creature, which may
have been modern mans direct ances-
tor. Men of approximately the present
type appeared in Europe about 10000
years ago and it seems quite probable
that two human species came into
contact
The remains indicate the Neander-
thaler's hearth fires burned during a
wetter somewhat warmer period than
the present. This was followed by a
gradual increase in the number Of
winter frosts. %
The indication Of warmer seas three
or four centuries ago comes from de-
terminations made on shells obtained
off the coast of Lower California. The
chemical composition of shells, it has
been determined by DR.. H. c. Urey
of the University of Chicago, varies
with the warmth of the water in which
they are formed.