The deposits called the Petrified Forests of Arizona extend over an area of more than 100 square miles and present great variety both in structure of the log-bearing strata and in characteristics of the petrified wood. Of this area about 40 square miles have been set aside as the Petrified Forest National Monument. When the monument was established in 1906 it contained about 90 square miles, but was reduced to its present size in 1911.
The term "petrified forest" has occasioned much misunderstanding. Many persons having heard of the forests expect to see a large group of standing petrified trees, more or less intact, or at least standing trunks or stumps as they occur in the petrified forest of Yellowstone National Park. No standing petrified trees can be seen in the Petrified Forest National Monument, however. The petrified tree trunks, more or less fractured, dismembered, and lacking the branches, all lie prostrate on or in the ground. It happens that there are a few upright stumps, but they belonged originally to horizontally embedded trunks and have been tipped to their present standing position. The region may be properly described as an eroded deposit of petrified drift logs, or the buried, petrified, and resurrected remains of a forest that grew somewhere else millions of years ago. Scientists place them as belonging to the Triassic period, making their age approximately 200,000,000 years.
The monument contains three principal districts, called the First, Second, and Third Forests. Geologically they belong to the same layer, but erosion has produced different results in the three areas; also the color and texture of the wood varies considerably, so that a visit to each place is well worth while.
The First Forest, the smallest of the three, contains sections and fragments of logs that were once bedded in the upper layers of clay and sandstone which have now crumbled away with the exception of some knolls and spurs. Enough of the sandstone capping remains to indicate the continuity of the original mesa in which the logs were entombed. In this cap rock can be seen many remnants of logs still firmly held in place, awaiting the erosion of coming milleniums, while their ends, divided in many sections, adorn the gullied slopes below. The fantastically carved escarpments, with banded colors, form a picturesque setting for this deposit.
The Natural Bridge is found about one-half mile to the east. This bridge is a petrified log about 100 feet long, originally incased entirely in sandstone. The crumbling of this stone has exposed the largest part of the trunk and, beginning with a small channel under the central portion, erosion has carved an arroyo under the log, so that it now forms a bridge of about 50-foot span. The length of the span and the immense weight of the trunk made it necessary several years ago to reinforce it with a concrete beam.
It should not be supposed that this tree grew on the rocky ledge, fell across the arroyo, and petrified. Instead, picture this region as the center of a vast basin overflowed by running water and gathering silt and gravel from surrounding higher elevations. Then imagine this tree, water-logged and no longer able to float, settling to its resting place on a sand bar, next being covered with more sand and pebbles that formed sandstone and covered by thousands of feet of clay and sand, then subjected to the ages upon ages of chemical action called petrifaction, which changed it from a wooden trunk to a mass of agate and carnelian (silica) without affecting its shape. Then picture the slow upheaval that drained the water from this basin; the gnawing of erosion through many thousands of years to remove the layers above this trunk; and the final crumbling of the immediately surrounding sandstone to expose the log and form the gully. Such in short is the story of this natural bridge.
The Second Forest lies about 2 miles south and a little to the east of the First Forest. It contains, in addition to the chips and scattered sections that are so abundant in the region, some rather well-preserved logs, a few of which are not entirely uncovered. The striking feature here is a number of logs of yellowish gray color and dull texture, quite a contrast to the more flinty and brightly colored specimens that prevail in the First Forest. This gray petrifaction shows under the microscope the minutest details of the original wood.
The Third or Rainbow Forest lies about 6 miles south and west of the first one. It surpasses the first two deposits in size, number of logs, and brilliancy of coloring. Here are found hundreds of logs in a good state of preservation. Stripped of branches, roots, and most of their bark, these huge trunks lie in great profusion, pointing in all directions. Many exceed 100 feet in length. If the missing tops were reconstructed they would indicate that the trees in their growth often reached 200 feet or more in height. The outer surface is generally a reddish brown, while the cross sections reveal every tint of the rainbow.
The west portion of the Third Forest is the place directly responsible for the name "Rainbow Forest." Here the colors of the wood reach their greatest intensity. The cap rock was partly worn away in the early stages of erosion and many deep ravines trenched through this bed of logs, after which the destructive agencies of weather through many thousands of years have reduced these trees to piles of fragments. The ground in every direction is literally paved with chips of agate, onyx, carnelian, and jasper.
A small museum housing some of the most rare and remarkable specimens of wood has been built in the Third Forest. A number of these specimens have been polished, and they exhibit in the greatest possible degree the wonderful coloring of the wood. No visitor should neglect the opportunity to see this collection. There is no charge for admission. At the museum is a registration book for visitors to sign.
Camp ground and water supply are within a short distance of the museum. The water supply, however, depends on the yearly rainfall, which is scant, and therefore can not fully take care of the demands made upon it by the great number of visitors. Tourists who intend to camp in the forest should preferably fill their canteens beforehand at Holbrook, Hunt, or Adamana.
The main point of departure for rail visitors to the monument is Adamana, on the Atchison, Topeka & Santa Fe Railway, although, if preferred, visitors may leave the train at Holbrook. From both of these points motor transportation to the monument may be secured. Occasionally heavy rains cause flood waters in the Rio Puerco and temporarily make the approach through Adamana impassable, as there is no bridge at this point. The monument can be reached at all times from Holbrook, but the distance is considerably longer than from Adamana.
During the summer season the Santa Fe Railway holds an eastbound and westbound train at Winslow two hours to give transcontinental passengers an opportunity to visit the monument. Eastbound passengers leave their train at Winslow and rejoin it at Holbrook. Westbound passengers reverse this procedure.
Motorists coming over the north branch of the National Old Trails Road may take the road through Adamana and the forest to Holbrook going west, or detour through the forest to Adamana going east. Traveling over the south branch of the National Old Trails Road there is a convenient detour 1-1/2 miles long and well marked with signs, 77 miles from Springerville and 18 miles from Holbrook. The winters are generally mild and this monument may be visited any day in the year.
It is unlawful to gather specimens of petrified wood of any size whatsoever within the monument boundaries. The penalty provided for violation of this regulation is a fine of not more than $500 or six months' imprisonment, or both.
Charles J. Smith, of Holbrook, Ariz., is custodian of the monument.