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Man
Columbus
Charlemagne
Blrtll
watks
dltcOY8fS
crowned
ol
on
America
HRE
..._
moon
1492
806
4B.C.
1969
2000
1000
o
regre ttably cut down in 1964. lts
age: at leas t 4,900 years! In addi–
tion, dead bristlecone logs and
stumps have been found that were
living over 8,000 years ago.
How do we know the bristlecones
are thousands of years old? The an–
swer is quite simple: Every year
most trees add a growth ring of new
wood. By counting these annual
rings, lhe tree's age can be deter–
mined.
Under ideal conatttons, trees may
grow quite rapidly, leaving easily
discernible annual rings. But bristle–
cone pines grow
in
arid. hostile en–
vironments where growth ca n
litera lly be microscopic. In fact,
bristlecones may grow so slowly that
the annual rings may be only a few
20
Rings
of
Antiquity
Bríst lecone tree-rlng chrono logies can be extended
thousands of years through the technique of
crossdating . Slnce tree rings vary in shape and
structure-dependlng on climatic conditions extant
when they were formed-a unique tree-ring pattern
or "fingerprlnt" is produced over a period of
years. By matching the lnner tree-ring patterns of a
living tree wlth the outer rfngs of even older dead
stumps
or
logs, a cross-dated continuous sequence
of annual ringa can
be
establlshed. As shown
schematically, a living bristlecone, such as the
4,600-year-old Methuselah tree, ls actually only the
f irst link In a tree-rlng chronology which now
extends over 8,200 years.
DIMd
MoMI
Great
tules
.._
......
Pyramlda
......
lfiiO
bulll
c.nMn
c.
2400
c .
1400
1000
thousandths of an inch thick-re–
quiring a microscope to be clearly
seen!
Matching
Trees: Cross
Dating
Perhaps even more amazing is that
tree-ring chronologies are not
lim–
ited by the age of the oldest tree. By
cross-dating the inner tree rings of
an old living tree with those in dead
stumps and logs, scientists have
bui lt up an impressive sequence of
bristlecone tree rings extending over
8,200 years into the past (see accom–
panying box).
Dendrochronologists (scientists
who measure time by coun ting
growth rings) have found that tree–
ring chronologies extending back
hundreds or thousands of years are
Wltllng
beglnl
In
Egypt
MllopotMIIII
very useful in historical and archae-
-~
ological studies. For example, when
~
an archaeologist finds a wooden
~
beam that was used
in
an ancient
~
building, he can often date the
:;
dwelling by matching the pattern of
~
tree rings in the beam with a master
~
tree-ring chronology for that area.
~
This technique has been especially
helpful in dating Indian ruins in the
American Soutbwest.
Tree rings also provide a natura l
source of information about local–
ized weather and climate patterns
prior to man's records. The date can
be found by counting the tree's
rings, and the climate is determined
by studying the size, density and
other characteristics of those rings.
Obviously, when the rings are small,
The
PLAIN TRUTH December 1977