Nature did not slight details in this work of substitution. Even to the
most minute particular the structure of the wood was replaced by the
intruder. Under the microscope it is possible to identify the kind of
wood represented. Dr. F. H. Knowlton has classified the major portion of
these trees as belonging to a species of conebearing tree now extinct,
related to the Norfolk Island Pine.
The logs lay buried for numberless centuries, but natural forces were at
work bringing them to the surface again. During the Tertiary Period, a
slow upheaval brought the submerged area to light. On and upward it
rose, until it now lies more than a mile above the level of the ocean.
Freed of its Old Man of the Sea, warmed and comforted by Arizona’s
brilliant sun and searching wind, the region lay at rest.
Slowly the fingers of time, tipped with wind and rain, broke through the
heavier sandstone above, and tore away the softer layers of shale and
marl. Bit by bit, the covering was lifted from the buried logs, and one
by one, the gem-like wonders saw the light of day. And what a glorious
resurrection it was! As the support was plucked from about them, they
left their sleeping places in the sandstone and marl and rolled to the
levels below. Frost tore at their vitals; rain fell into the crevices
and freezing there, expanded, until many of the finer logs are now
merely heaps of gleaming jewels, opaline and rose, lavendar and mauve,
deepest brown and softest yellow, black and purple, blue and red. In
their range of color they leave the beauty lover breathless. And these
colors are permanent, too, having endured through the aeons.
[Illustration: Courtesy Mrs. Adam Hanna
The most noted tree in the whole reservation. The Natural Bridge. About
four feet in thickness this 111 foot log measures 44 feet between the
sides of the arroyo.]
How? When? Why?
“How did it happen?”
That is usually the first question asked of the rangers in the Petrified
Forest.
In contact with eighty thousands or more tourists each year, there are
certain questions asked so many times that one learns what the average
person is most curious about in connection with these petrified trees.
Here are the most popular of these questions, together with the answers,
shorn of technical terms:
Why are none of the trees standing?
This is simply an exposed deposit of petrified logs that came here from
a distance, as driftwood.
How were they brought here?
Probably by rivers in flood periods. This region might have been the
mouth of a large river as is indicated by the crossbedded sandstone.
Why are they piled up in particular spots?
This was at one time an inland sea. The trees floated here, and were
swept by whirlpools or strong currents into eddys where they became
waterlogged and sank.
How long ago was that?
Men who have made a lifetime study of it, say it was from ten to forty
million years ago.
What became of the sea that was here?
Gradual upheaval of the country, aided by earthquakes and volcanic
action, raised this area and drained it. The Sierras were probably
brought to their present height during these disturbances.
What kind of trees are they?
Mostly an extinct species of cone bearing tree. (_Araucarioxylon
Arizonicum._)
How big were these trees?
Some of them are now a hundred feet long, and six to eight feet in
diameter. The Natural Bridge is one hundred and eleven feet long. The
height of some of these trees while standing was doubtless two hundred
feet or more.
Why did they turn to rock?
They did not really turn to stone. Silica and minerals in solution were
forced into the wood, dissolved it, and replaced the wood cells with
their own substance.
How is it polished?
By a process of grinding with carborundum and diamond dust, then rubbed
with leather buffer. It approaches the diamond in hardness and an
ordinary emery wheel will scarcely mark it.
What is the weight of the petrified wood?
About 200 pounds to the cubic foot. It varies.
Why can’t visitors take specimens away with them?
First: Because it is against the United States Law. After that comes
consideration of future visitors to the Petrified Forest National
Monument. When one reflects that there are about eighty thousand
visitors here annually and that if each visitor took what pleased him,
it is an unrefutable fact the best specimens would speedily disappear. A
visitor would not be satisfied with one small piece. There would be the
home folks to consider; the neighbor that fed the left-at-home cat, and
the friend who loaned his kodak for the trip. These would all need
souvenirs. It would be difficult to choose among several beautiful
pieces and so a compromise would be made by taking all of them.
[Illustration: Courtesy National Park Service
They leave their sleeping places in the sides of the marl hills and
roll to levels below.]
What is a National Monument?
An area set aside by the President of the United States to preserve
regions of scientific, historic or prehistoric interest.
What is the area of the Petrified Forest National Monument?
25,908 acres.
Who has charge of it?
The National Park Service, one of the largest and the most important
bureaus of the Department of the Interior. A custodian and several Park
Rangers are the immediate representatives of the Government on the
Reservation.
[Illustration: Courtesy National Park Service
As the soil slowly settles beneath these giants their weight dismembers
them. In this way they were broken in the lengths we find them now.]