Evening star., 1932-06-26

(COnblIlueu FTOm r1ISI EdBeD
the aspect of tropical vegetation. Yet
they are essentially temperate climate
species.
Armed with this clue, Drs Ralph W.
CLANCY and Erling Dorf of the Car
negie Institution staff, set out to find
them They believed that the forests,
as well as the animal life, had been
driven southwark over many genera
tions as some mysterious danger took
place in the climate. They made an
intensive search through the British
West Indies and the jungles of British
Guiana but found nothing in common
with the ancient vegetation Of Western
North America. 1t was not until they
came to the countryside around the
Venezuelan city Of Merida in the foot
hills of the Andes, cold and foggy with
the snow-covered mountain peaks
around it although 1t lies almost on top
of the Equator, that they found what
they sought.
Close Resemblance Seen.
"In the mountain forests" says DR..
Chaney, when the leaves are COM
pared with the fossil imprints in the
rocks of Western North America a
close resemblance is at one apparent.
Two-thirds Of the fossil species have
close relatives in this temperate rain
forest and the student of earth his
tory may conclude that a forest of
very like appearance. and with very
much the same climate requirements,
once, extended far northward into
Oregon.
Not only the trees, but the animals
have close similarity to those which
once ranged into temperate latitudeS
The tapir and the tree sloth which today
are limited to forests near the Equator
have left petrifled bones in North
America which tell of their wanderings
far to the north of their present homie
The abundance of alligators and large
dinosaurs is suggestive of the age Of
reptiles when these animals were wide
spread as far North as Canada and
Mongolia.
In the depths of this forest lie
many of the secrets OF the past. Re-
constructing the history of the earth
on the basis Of the fossil fioras of
Western America and their living
equivalents a trend may be observed
during past ages from a moist, warm
climate to the relatively dry and cool
conditions of our day. Just what were
! the causes Of this gradual change is a
difficult question to answer. Varia-
| tionS in the amount of heat given of
| by the sun or in the insulating power
Of the atmosphere, shifting in position
| Of continental masses with a resulting
alteration of currents of water and air.
! and many more factors may have con-
| tributed.
Suitable Conditions Sought.
The fact of this climate change is
| fully demonstrated by the migration
southwark of the forests and the ami
mails which lived in them, to the only
part of the world where suitable con-
ditions Of temperature and moisture
still exist
"A long line of active volcanoes ex-
! tending from Mexico through Central
America and down into the Andes gives
further details for the picture Of condi-
tionS on our Pacific Coast in the distant
| past. Over thousands of square miles
IN Southern Guatemala there fell this
Winter shower of volcanic dust which
| covered the ground, the roofs and even
the leaves of the forest with thin,
| gray mantle. Thick layers of volcanic
sediment, now compacted into solid
rock, are widespread on the borders OF
the Sierra Nevada in California and
Of the Cascades in Oregon. These rep
resent the eruptions of ancient VOL
canoes which buried the landscapes of
long ago in showers of dust. The re-
mains Of animals and plants entonbed
in the volcanic dust furnish the fossil
record used by the paleontologist in
reconstructing the life Of the past.
I'm Western North America volcanic
activity has largely subsided. and a
| gradual change in climate has resulted
in the extinction Of many types of
plants and animals. To the South, vol
canic activity has continued down to
our own day. A hot, moist climate has
permitted certain plants and animals to
| linger on into the present. Thus We
see our country as 1t used to be-vol-
canic peaks manteled by rain forests
| in which roam curious beasts