Evening star., 1936-12-08

Sixty million years ago vast forest
fringed the Arctic Circle in North Amer
lea, Siberia and Greenland.
1t contained the ancestors of most Of
the trees now found in the temperate
United States-redwoods, pines, hem
locks, chestnuts, naples and beeches. It
tundra during the Eocene geological pc
riod, or the "dawntime" Of present-day
life when Towering plantl singing birds
and mammals first made their appearance.
A notable part of this forest was made
up of ancestors of the present giant red
woods of California, the oldest Of living
organisms.
The Eocene climate was mild in the
Far North. In the temperate zone 1t
was at least semi-tropical. After 10 or
20 million years it began to grow colder
and the great forest packed up and
moved south for the Winter of the ages
whose icy winds were beginning to blow
through its branches. This was perhaps
the most epic migration in history. 1t
required millions of years for the trees
to reach the temperate zone and find
themselves comfortable new homes,
while the semi-tropical forests in their
path in turn were pushed South.
Such Is the story uncovered by plant
psychologists of the Carnegie Institu
ton of Washington. The story OF the
migrating forest will form notable part
Of the annual Carnegie exhibit which
opens Saturday, following the annual
meeting of the trustees at the admin
istration building Sixteenth and p
streets, Friday. The hypothesis of the
great southwark march Of the woods
through the ages, long before there was
any human habitation of the New World
is based on q growing collection OF fossil
remains from the semi-Arctic zones of
both North America and Asia.
There is increasing evidence" says
the report, "for the belief that the cli-
mate over the whole of North America
was more mild during the Eocene period
than it is today. Not only did tenn
perate forests of redwood and oak extend
far north of the present tree line, but
trees now characteristic of the tropics
have been recorded from Eocene rocks
of middle latitudes in the United States.
Fig, avocado, bread fruit and tree fern
suggest past climate in Tennessee and
Oregon like that now found in Mexico
dllo SCllIldl AllCllCd I1Cdty
and an absence of frost must have con-
tributed to the existence of such sub
tropical and tropical plants in these now
temperate regions.
"The causes of climatic change are not
fully understood. Possible changes in
the amount or character of energy given
of by the sun during geological history
doubtless resulted in fiuctuating tenn
peratures. At some times the presence
of vast quantities of ash blown into the
air from volcanoes may have lessened
the amount of solar energy which has
reached the surface of the earth. Ease
Of distribution by winds and water cur
rents of the heat which reaches the
earths surface also has been q factor
in terrestrial temperatures of past ages.
Just as clogged pipe may result in
freezing or over-heating, so impaired cir
culation of ocean and atmosphere may
be responsible for extremes Of tempera-
ture.
When the continents were low with
broad, shallow seas such as Hudsons
Bay extending over them, circulation was
greatly facilitated and mild climates were
increasingly widespread. Subsequent