The Ely miner. [volume] (Ely, Minn.) 1895-1986, 1930-02-28

the trees In our forests show the swing
Of Times pendulum and put down
mark. They are chronographs, record
ing clocks, by which the succeeding
seasons are set down through definite
imprints. Every year each pine adds
layer of new wood over its entire
living surface of trunk and branches.
If every year were exactly the same,
growth rings would tell the age of the
tree and little more. Only in rare
cases would they record exceptional
events of any interest to us. But a
tree is not a mechanical robot; it is
living thing, and its food supply and
adventures through life all enter into
it's diary. A flash of lightning, a forest
fire, insect pests or falling neighbor
may make strong impressions on its
life and go into its diary.
But in the arid regions of our South
west, where trees are few and other
vegetation scarce, the most important
thing to man and trees is rainfall. SO,
in the rings of the talkative pines we
find lean years and fat years recorded.
The same succession of drought and
plenty appears throughout the forest.
This fact helped vastly in the dating
work, for certain sequences of years
become easily recognized from tree
to tree, county to county, even from
state to state.
No living, diary-keeping tree in the
semi-arid region inhabited by the
Pueblo Indians goes back more than
few hundred years; and the giant
sequois of California register in
different way those seasonal fuctua-
lions that control the pines Of north
ern Arizona. So when the investigators
reached the earliest date which the
oldest living Misunderstanding Arizona
tree could tell about, it became neceS-
sary to search for beams that had
been cut and used by man before the
now living trees took up the story.
Here and there they found beams the
latter years of which were contem-
poraneous with the early life of trees
still living.
By arranging these beams in their
proper sequence, so that the inner
diary entries Of each one dovetailed
into and matched the outer entries
of its predecessor, the workers OBJ
tanned an unbroken succession OF
beams and trees.
In this way, step by step, they
pushed historical dates back further
and further until they found a beam
whose earliest ring was formed A. ID.
1860 less than a century after the
children's crusade.
The development of this tree-ring
study presents an example of how
scientific research starting with def
mite idea may lead into unforeseen
channels. Originally Doctor Douglass
work was a study of sun spots. 1t is
known that there is periodicity In
their occurrence; they are most num-
erous at intervals Of eleven years. AS
an aid in that astronomical inveStiga-
ton, he studied trees, for solar
changes affect our weather. and wealth
er in turn affects the trees in AriZona's
dry climate, as elsewhere.
Sun Spots and Tree Rings.
The study of sun spots and their in
fuence upon weather and the conse-
corded by tree rings progressed most
successfully. The first confirmation of
the general Interpretation Of re-
lationship between tree rings and sun
spot periods came in most dramatic
way.
spot cycle had been easily found in
Arizona pine trees. The regularly re-
curing periods had been recorded
for 500 years by tree rings, except
for the interval from 1650-1725. During
that rs years the tree rings gave no
evidence of periodical changes in the
weather such as were to be expected.
Several years after this puzzling
fact had been encountered the late
DR.. e. Walter Maunder, an eminent
English astronomer, unaware of the
findings, wrote to Doctor Douglass
that he had discovered that there were
no sun spots between 1916 and IT'S,
and that if the tree rings did not in
dictate some effect of this absence of
sun spots, the work was being conduc-
ted on an erroneous hypothesis.
The coincidence between the failure
of Arizona trees to register any sun
spot effect upon the weather during
those years, and establishment of the
fact, by entirely independent study,
that the customary sun-spot cycle did
not occur during approximately the
same period of years helped confirm
the relationship between the growth
of trees and solar changes.
Specifically, the tree-ring calendar,
as finally worked out, told these things
about Pueblo Bonito, the ruin whose
date problem brought about the six
years search: It's earliest recovered
beam was cut in A. d. 919 from a tree
that was 219 years old when cut; and
Pueblo Bonito reached its golden age
In 1867 and was still occupied in 1127.
Not only has the age Of this great one
time metropolis Of the Southwest been
fixed, but the tree-ring calendar has
also dated some 40 other ruins whose
time Of occupancy hitherto had been
unknown. Important among these Is
the Mesa Verde group of Colorado, in
which Cliff Palace is dated 1913; Oak
Tree House, 1112; Spring House, 1115;
Balcony House, 119O-12O6; Square