Evening star. [volume] (Washington, D.C.) 1854-1972, 1940-11-07
Of Stars, Men
And Atoms
Notebook of Science Progress
In Laboratory, Field
And Study
BIZ Thomas r. Henry.

~ AbOHtGo &ts AAS"f9s
About 45o000,00o years ago a shallow
sea about 500 miles wide reached from
the Arctic Ocean to Lower California.
High land in about the. position of
the present Sierra Nevada Mountains
was its western shore On the east it
was bounded by lower terrain OF
which the granite cores of some of the
ranges in the present Rockies such as
the Wind River, Teton, Bighorn and
Yellowstone Mountains are surviving
relics.
Into embayments of this ancient sea
this summer went DR.. Charles E. Resser,
Smithsonian Institution paleontologist,
in search of fossils of the primitive
creatures who lived in its clear waters.
From these fossils can be reconstructed
a map of this part of the earth through
the so-called Cambrian geological era
whose rocks contain the earliest records
Of living things.
The creatures of the low sea were
trilobites, somewhat similar in appear
ance but not directly related to crabs,
and brachiopods, shelled mollusks nearly
all forms of which are extinct. They
were fairly high forms of animal life,
the end product Of what must have
been long evolution nearly all trace
Of which is lost. From the types found
IN the rocks of any particular place
the location can be roughly dated in
the nearly 100000 0o0-year Cambrian
era.
A hypothetical shore line of the old
sea was found by DR.. Resser in the
Green River Lakes region on the west
side of the Wind River Mountains in
Wyoming. An isolated region far from
the haunts of men, an aura of antiquity
hangs over it. In the granite rocks
through which flow the swift head
waters of the Green River, one of the
chief tributaries of the Colorado DR..
Resser found a stratum between $50
and LOCO feet thick in which there
were splendidly preserved trilobite and
brachiopod fossils. When the creatures
persisted generation after generation
they had become embedded in the sea
bottom. Sediment, slowly washing from
and covered them. This was repeated
millennium after millennium and finally,
in the course of earth upheavals through
millions of years, the sea bottom ooze
became rock.
Ordinarily, DR.. Resser says, Cambrian
deposits were at least twice as thick,
because of the enormous stretch of
time covered by the era, during all of
which slow sedimentation was in prog
ress. Their shallowness here is evidence
that the region must have been very
close to the eastern shore.
AT no place, he says, was it very
deep. This is shown by the fact that
trilobite and brachiopod shells are found
badly broken up by the action of the
tides sweeping along the bottom and
churning the Dose. Also presumably it
was a very clear sea. In the water
grew quite primitive forms of plant life,
somewhat similar to the kelp of today.
There were also algae which secreted
lime to form large beds in some places.
DR.. Resser visited other areas of this
ancient ocean in the Grand Canyon,
the Wasach mountain range of Utah,
and the Black Hills country where some
Of the chief gold, silver and lead de-
posts are in rocks formed during this
period.
These regions represent the middle
millenniums Of the Cambrian. Later the
sea spread eastward over the present
Rockies and Great Plains as far as
Wisconsin and Missouri. In Wisconsin
DR.. ReSser explored the most complete
records yet found of the closing DAYS
of the era when its peculiar forms Of
life were reaching the end of their days
of dominance on earth.
At that time, he points out. there
were granite hills in the country now
covered by the Rockies. None of them
were very high. Their tops emerged as
barren islands out of the placid water.
So far as known there was no life on
land at that time. Even the first land
plants had yet to make their appear
ance.
simultaneously with this long, narrow
western sea, DR.. Resser says, the fossil
records show that a similar arm of the
Arctic extended southwark in a shallow
trough now filled by the Appalachian
chain from Labrador to Georgia and
Alabama. From time to time the waters
withdrew and then came again. Be-
tween the two seas there was a wide
stretch of barren land extending from
approximately Western Pennsylvania to
little beyond the Mississippi
Everywhere, he says, Cambrian fossils
are scarce and the story of the ancient
time must be reconstructed from slender
clues. But all evidence, he explains
points TO the conclusion that it was a
very slow-moving, peaceful time with a
deadly monotony over all the earth
During most Of the period, it seems there
was fairly equable climate and in its
shallow seas were developing, without
leaving many records, the ancestral
forms of the higher forms of life that
in succeeding millenniums were to
emerge from the water to populate the
| land
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