Evening star., 1941-03-20
Of Stors, Men
And Atoms
Notebook Of Science Progress
In Laboratory, Field
And Study
Bu Thomas r. Henrv.

By ThOMGS n. HenrU.
The earth's three electric roofs are
being explored up to heights of about
2l8 miles with special techniques de-
veloped by physicists of the Carnegis
Institution of Washington.
1t now is well known that in the
high atmosphere there are three layers
of extremely tenuouS ionized gases dues
for the most part, to ultraviolet light
from the sun knocking outer electrons
from atoms i'll its path. Without these
layers radio transmission would be i'm
possible. The radio waves would escape
into space. Instead they are bent
around the earth.
The lowest of these. the so-called E
layer which is responsible for most OF
the radio wave bending, Is found at
an altitude of about ITO kilometers.
Above it are the F-one and F-tWo
layers at heights of 225 and $50 kilo-
meters respectively. At night the lat
ter two combine at about $50 kllo-
meters to form a common F layer.
The attitudes of these layers were
determined by means of radio echoes
the time required for radio waves moving
with the speed of light to be reflected
from them back to the earth. BY these
same radio waves, using now
abundantly verified hypothesis known
as the magneto-ino theory, the Carnegie
physicists are able to determine the
density of the ions, or electrlneo
particles in each of these layers ana
are opening up new field for space
exploration.
For the first time by this means
1t is possible to determine what nap
pens to the upper atmosphere WIN
the cyclic variation of spots on the lace
of the sun, due supposedly to titanic
WhirlWindS in the solar atmosphere
Between the minimum and maximum
number of sunspots there Is an IN
crease of about 300 per cent IN the
density of the electrified particles In
the uppermost layer while there Is an
increase of about so per cent in the
two lower layers.
Among the problems which 1t Is
hoped to solve by the new technique
it is explained by DR.. l.. Y. BerKner OF
the staff of the Carnegie Institutions
Department of Terrestrial Magnetism,
is the level of flow of the great electric
current systems in the earth'S outer
atmosphere. Present indications are
that the most suitable conditions Tor
maximum current-f1ow exist at level
about 70 or 80 kilometers above the
earth's surface.
l. Fossil imprints of leaves in rocks,
preserved over span OF l1o'ooo'ooo
wears, are giving plant paleontologlsUs
elimpses into one of the great transltlon
ages in the history of the world.
This was the Triasslc geological
period, when the great reptiles were be-
ginning their 100000 900 year doml-
nation of the world and plants were
taking on forms not unlike some OF the
ferns and conifers of the present al
though long ages were to pass before
the first towering forms made their
appearance.
The Carnegie Institution OF Washing
ton has just published an account OF
the Identification of fossil plant lorms
from the weird Blue Forest OF Arizona
bv LYMAN H. Daugherty of San Jose
State College, California. He mas peeh
able to reconstruct tentative picture
of the ancient forest, where plant
evolution was making rapid progress
and contrast it with the rather desolate
scenery of the same land today.
The Temperatures, it is deduced from
the Triassic ferns. were sub-tropical to
tropical-much warmer than those
found in the same region today through
much of the year. There appears TO
have been sufficient rain to insure
permanent streams and swampy con-
ditions in the lowlands, intersperseo
with intense dry periods. The growth
LAYERS of the fossil wood indicate that
most of the rain fell during growing
season, with very little at any other
time of the year.
The same combination of temperature
and rainfall is to be found IN the
savannas of the tropics today. Here
dense forests border the streams or
OCCUPY narrow valleys, while the open
slopes and uplands are characterized
by more open forests with scrub and
grasslands. Plants which fit both these
habitats appear to have mingled IN
ancient Arizona.
The size of the logs in the petriaed
forests and the thickness of their growth
layers, it is pointed out, give evidence Oh
a Triassic climate more favorable for
trees than obtains in this region today
They must have lived on the borders OF
streams. or on moist slopes where there
WAS an abundance of water during the
growing season.
1t has long been believed that these
logs were washed into their present
locations, perhaps from a considerable
distance. But some of them, MT
Daugherty believes, must have grown
very near where they are found today
Some stumps in the Blue Forest actually
have roots which can be traced more
than ten feet. Complete leaves and
leafy branches of some of them also are
evidence that they cannot have been
transported very far. These more DELI
cate parts almost certainly would have
been destroyed or lost during such q
transition.