THE " FOSSIL FOREST " OF ARIZONA 



By George P. Merrill 



Head Curator of Geology, United States National Museum 



THE so-called " fossil forest " 1 of Arizona lies some six miles south of 

 Adamana, a station on the Santa Fe Railroad, in Apache County. 

 The expression "so-called" is used for the reason that it is not a 

 forest at all, nor does it bear any resemblance to one, being rather a collec- 

 tion of silicified logs. Could one imagine a collection of saw logs ponded 

 back in a boom and waiting their turn at the mill, and that further this 

 collection had become water-logged, sunken and buried by sediments, he 

 would gain a very fair idea of the conditions which apparently at one time 

 prevailed during the history of the region. There is nothing to indicate 

 that the trees even grew near the locality where the logs are now found. It 

 is apparent rather that they grew at some distant point and were drifted 

 by stream action into eddies after having been reduced to mere trunks or 

 logs through the loss of their leaves and smaller limbs. Here, in various 

 stages of decay, they sank and became buried by the accumulations of sand 

 and gravel and subsequently silicified. Nor are the logs now, with few 

 exceptions, even in the position of their original entombment. The beds 

 in which they once lay have been cut through by erosion and the logs settled, 

 or rolled down to a lower level. In this process they became more broken and 

 under alternations of blistering heat and freezing cold have been splintered 

 and chipped, oxidized and polished, until the country for an area of many 

 square miles is covered with a bewildering array of broken trunks and frag- 

 ments of agate and jasper, varying from nearly colorless through yellow and 

 red to the most brilliant carnelian. The few logs which remain in the posi- 

 tion of their original entombment are widely scattered and the one best 

 known to the tourist is that forming the so-called " natural bridge," where 

 an enormous log has been undermined by the action of temporary streams 

 and remains supported at both ends spanning a chasm of nearly fifty feet 

 in width and twenty or more feet in depth. 



It is apparent that there were at least four eddies in which the logs 

 accumulated in the area now comprised within the reservation known as the 

 Petrified Forest National Monument of Arizona. The first lies some six 



1 Note. — The area of the Petrified Forest is well represented in a map issued by the 

 United States Geological Survey. The map published in December, 1912, is the result of a 

 survey made two years previously and shows the location and topography of the six separate 

 forests. The trees are perhaps millions of years old and consist to-day of many-colored 

 agate, an exceedingly hard and tough stone. Visitors to the American Museum can see many 

 interesting specimens from the Petrified Forest. In the gem room are several particularly 

 fine polished slabs of agatized wood from near Adamana and in the mineral collection is a two- 

 foot section of agatized log from the same region. In the corridor on the ground floor leading 

 to the building-stone collection is a considerable series of specimens illustrating the several 

 phases of growth and fossilization collected by Dr. E. O. Hovey under special permit from the 

 Department of the Interior. 



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