The sun. [volume] (New York [N.Y.]) 1833-1916, 1914-06-14

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lar phenomena Of to-day.
AT the dawn OF human history the
climates Of central and western Asia,
the northern border OF Africa, the
southern parts OF Europe, such es
Greece and apparently ali continental
regions having the same kind Of SUBJ
tropical climate. with winter rains and
summer droughts. appear to have been
decidedly more moist and a trine cooler
than Ia now the case. The change from
the climates of that time to the drier
conditions OF the present apparently
took place irregularly in a pulsators
fashion. comparison of the state Of
anairs 1000 years ago or more with
that or to-day suggests that the slow
swing from the cold, moist climate OF
:he last glacial epoch to the warm.
dry climate Of the present post glacial
epoch Ia as yet scarcely completed.
| "A fuller study OF the data for inter-
mediate periods suggests that the swing
Ii taking place In waves or pulsations.
Apparently climatic cycles OF all sizes
are now in progress. The shortest are
those OF three, eleven and thlrty-five or
thlrty-six years. Next come cycles
measured In hundreds OF yenrs. Evil
dence in Asia indicates that cycles last
ing considerably more than 400 years,
possibly 5000 or more have occurred
during historic times. The series Of
cycles Is completed so far as recent geo.
logical time Is concerned by glacial
epochs and glacial periods that appear
to have lasted thousands and tens OF
thousands of years.
In the Santa Cruz Valley, whers
Tucson is located, 1t appears that at
present not more than 1000 or 5000
people could find sustenance merely
from agriculture. or from local re-
sources, without modern railroads and
other means OF outside assistance. The
part OF the valley which Is now cnpsN.
Of cultivation contains ruins which in
dictate that all the available land was
utilized in the past. Below the point
where irrigation is now possible there |
are three large groups of ruins, and the |
three together must have had as many |
people as the higher regions where there
Is still water. In other words, 1t seems |
least twice as many people as u could |
at present support, and half Of these
lived where the white man cannot now |
get living from agriculture.
Ruins such as these. however, are
not the most important line Of evidence
here In America. In order to test the
matter In a wholly different way we
spent two seasons in California and
measured the thickness OF the rings Of
growth OF about $50 Of the giant Sc
quota trees which had recently been cut.
These trees grow In a region where
there are winter rains and summer
droughts like those Of western and CEN
trail Asia. The thickness Of the rings
depends largely upon the amount Of
rainfall.
The trees confirm the theory OF pull
satory climatic changes. They appar-
emily show that the climate Of the
earth is subject to pulsations having a
period or centuries. In the third place
the rate OF growth OF the trees indicates
that In the distant historic past the
moist epochs were on the whole more
moist than the similar epochs In more
recent times. Fourth and last We are
led to conclude that the main climatic
changes OF America are synchronous
with those OF Asia and are OF the same
kind.
still another kind Of evidence quite
different from any yet found in Asia is
derived from the wonderful ruins Of the
Maya civilization in Yucatan and
Guatemala. The ancient Mayas reached
the height OF their civilization in the
first centuries Of the Christian era, then
they declined greatly, but revived about
500 or 1000 A. ID. and built some Won
derful ruins In northern Yucatan.
Their greatest achievement, however.
was the invention OF the art Of writing.
They were the only people in the west
ern hemisphere who did this. In almost
every respect they were far in advance
or any other race that ever lived in
America before the days OF Columbus.
The most extraordinary thing about
them Is that they made this great de-
velopment in almost the worst place I'm
North America. Many OF their ruins
are located In what is now the densest
kind Of tropical forest. where the
present inhabitants are In the lowest
stages OF civilization and are extremely
few in numbers. Some are mere
savages. Agriculture is practically i'm
possible because the rainfall is so great
and the dry season so short that the
forest cannot be cleared and the brush
burned. and IL by chance a clearing Ia
made the native vegetation grows I'D 80
fast that it chokes the crops. More
over the whole country ia terribly
afflicted with fevers, so that the natives
are weak and inefficient and very dull
In mind.
1T seems impossible that In the days
or the Mayas such conditions could
have existed. Either those ancient
people were the most wonderful race
that ever existed or else the feyers
were less terrible than now and the con-
ditions OF agriculture were easier. All
this would be possible and conditions
would have been favorable at just the
times when the Mayas were most pros
porous II the pulsatory climatic theory
We're true. According to our present
knowledge II seems as II the climatic
changes with which we are dealing con-
sisted OF showing OF the worlds
climatic belts either toward the equator
or away from II. When the belts were
showed equatorward places like Cali
fornia or Greece would be more moist.
while in places further toward the
equator the present dry summers OF the
snbtropical belt would prevail Thus
while Arizona would he moister than
now Guatemala and Yucatan womb hs
Wal.