ON A REMARKABLE FRAGMENT OF SILICIFIED 

 WOOD FROM THE ROCKY MOUNTAINS. 



BY H. ALLEYNE NICHOLSON, M.D., D.Sc, P.E.S.B., 



Professor of Biology in the College of Physical Science, NewcastU'on-Tyne ; and 



W. H. ELLIS, M.A., M.B., 



Lecturer on Chemistry in the School of Practical Science, Toronto. 



The specimen whicli forms tlie subject of tlie present communica- 

 tion was brought by the late Mr. John Worthington, of Toronto, 

 from the well-known ''petrified foi-est" of Colorado. As to the 

 locality from which the specimen was derived, we can, of course, 

 merely speak at second-hand ; but the petrified forest in question is 

 a place familiar to, and much visited by, tourists; and there is both 

 external and internal evidence to prove that the specimen was truly 

 brought from there. The " petrified forest " of Colorado is situated 

 not very far from Colorado City, at a supposed height of about seven 

 thousand feet above the level of the sea, in the immediate neighbour- 

 hood of the lofty mountain known as Pike's Peak, and near to the 

 celebrated Ute Pass. The forest occupies the bottom of a broad 

 depression which covers an area of from one to two thousand acres. 

 All round the edge of this area are placed numerous erect stumps of 

 silicified trees, most of which are three or four feet in height, and 

 from ten to twenty feet in diameter. The stumps are apparently 

 placed at some little elevation above the bottom of this depression, 

 and are said for the most part to be placed at about the same level. 

 These phenomena would strongly support the belief that these ancient 

 trees grew upon the margin of a lake which has now disappeared. 

 Various considerations render it probable that these silicified trees 

 are the remains of conifers belonging to the genus Sequoia, and 

 nearly allied to, if not identical with, the "giant-trees," Seqi^oia 

 gigantea, of California. The great size of the stumps would render 

 this conclusion almost a certainty, and it is fui-ther supported by the 

 fact that a very similar silicified forest has been described by Pro- 

 fessor Marsh as occiirring near Mount St. Helena, in California 

 {^American Journal of Science and Arts, Vol. I., April, 1871). . From 

 the occurrence of a bed of vesicular lava in direct connection with 

 the forest, we may surmise that the forest was overthrown and biuied 



