The Petrified Forest

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In Arizona, that land of mystic beauties and many wonders, lies a great tract of land that, once upon a time, was covered with waters of the sea. How many centuries ago the ocean waves sparkled and rippled over what is now the desert, no one can definitely say. But from the nature of the stratum is which great logs are embedded, and the fossilized reptiles found, it is known that they were entombed during the Triassic age, many millions of years ago.

Petrified logs are found over a wide area, more than a hundred square miles being covered with varying amounts of the “stone” trees. This fossilized “forest” is greater in area, more highly colored, and contains more petrified wood than any like deposit in the world.

Many visitors who have heard of the “forest” drive through miles of the Reservation and ask at the Museum where they can find the Petrified Forest. Inquiry discloses that they expected to find an area of standing trees, trunks merely turned to stone, branches and all. Perhaps they have seen one or more such trunks in Yellowstone National Park and think to find hundreds of them here. Yet, when they learn the story of these fallen monarchs, and catch a glimpse of the dazzling beauties of agate and carnelian, jasper and onyx, no signs of disappointment are seen. Let the visitor but leave his car to view the logs, and step by step he is led on by here a gleaming fragment of carnelian, and there the soft sheen of jasper and topaz. It is like the carpet of Fairyland.

These trees did not grow where they lie, or even within many miles of where they are found. They were carried from a long distance to this region by flood waters, and after whirling and drifting around in the inland sea then covering the land, they became waterlogged and finally sank to the bottom, where some eddy or whirlpool carried them. Here they lay for countless centuries, slowly being covered by silt and sand, while yet other logs came to rest above them. Thousands of years elapsed during this drifting and sinking into oblivion under the ooze of this Triassic Sea. And then came Old Ocean, later on in the Mesozoic Age submerging the entire region and adding its weight to the terrific pressure already brought to bear on the burial place of the giants. This pressure packed the sands to stone, and compressed the clays to shale. Already the logs were impregnated with a strong solution of silica, with iron and manganese also present, and the pressure forced it into every fiber. Atom by atom the cells of the wood were dissolved and replaced by the silica, which hardened, taking the exact shape of the cell it destroyed. While the logs were probably partly petrified before the influx of the ocean waters, a great many show that enormous pressure was brought to bear while they were yet flexible.

Some logs recently brought to light by the summer floods, are mashed almost flat, cross sections measuring eighteen inches one way and more than five feet the other.

Courtesy National Park Service

Cross section of log showing natural fracture.

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.

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.

                                                                                                                                                                                                                                                                                                           

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