10 TRAXSACTIONS OF THE [OCT. 5, 



The Avood is generally found projecting out of tiie volcanic ash 

 and lava, which is covered with sandstone to the depth of from 

 twenty to thirty feet, and lies exposed in the gulches and basins 

 where" the water has worn away the sandstone. 



The silicification probably took place in the following manner: 

 — The trees were overthrown and covered with volcanic ash and 

 tufa; heated silicitied waters percolating through the ash, cooled 

 on reaching the tree level, and thus produced conditions favor- 

 able to silicification. The variety of colors in the wood is due to 

 oxides of iron and of manganese. It is possible also that the ash 

 was deposited partly in water and thus heated it. There is every 

 indication that the deposit is of considerable depth. Over the 

 entire area the trees lie scattered in all conceivable positions and 

 in fragments of all sizes, sometimes resembling a pile of cart 

 wheels. A tree, twenty feet in length, is often found broken up 

 into as many sections. These multiplied fractures are the result 

 of alternate heat and cold acting on the water collected in the 

 fissures of the tree. 



Tlie highest point in the park is some two hundred feet above 

 the surrounding level, and it is here that the buried trees can be 

 seen to the best advantage. Some of them are one hundred and 

 fifty feet long and ten feet in diameter, and lie exposed in all 

 conceivable positions. One section of a tree, which has been 

 broken up, measures eight feet in diameter, ten feet in length, 

 and weighs several tons. The tree was origiiudly about two 

 hundred feet long. Some pieces of the trunks of these trees, 

 which were brought to New York, range from eight inches to 

 three feet in diameter, and from twenty-five to one thousand 

 pounds in weight. The perfect preservation of these trunks is 

 remarkable. Tiie rings are so distinctly visible as to convince 

 even tiie most incredulous of their organic origin. 



The most interesting points in the park iiave been suggestively 

 named. The Agate or Natural Bridge, Agate Gulch, Amethyst 

 Point, and Fort Jasper. 



The most remarkable feature of the park, and a phenomenon 

 perhaps unparalleled, is the Natural Bridge of agatized wood, 

 formed by a tree spanning a canon forty-five feet in depth, and 

 fifty-five in width. In addition to the span, fully fifty feet of 

 tlie tree rest on one side, making tlie tree visible for a length of 

 over one hundred feet. Botii ends of the tree arc imbedded in 

 the sandstone. It averages three and a half feet in diameter, 

 four feet at the thickest part and three at the smallest. Where 

 the bark does not adhere, the characteristic colors of jasper and 

 agate are to be seen. 



Although silicified wood is found in many localities throughout 

 the world, nowhere is it so beautifully colored as at this place. 



