They were of various sizes, from half an inch in diameter to three or four inches, but were more usually about an inch and a half or two inches. Their substance was sandstone of the same kind as the rock they were in; but the part resembling the bark was somewhat harder, which enabled it to endure longer than the rest of the stone, and thus project above its surface.
The colour of the outside was sometimes of the same yellowish tint as the other parts of the rock, but was more frequently dark grey, owing to their greater durability permitting the lichens to grow upon them. When the dark coloured pieces were broken, the internal part was yellow. Often a piece of the bark appeared wanting, and then the central part of the branch, or that corresponding to the wood was smooth, but the outside of the cortical part was rough and corrugated. Some were straight, others a little crooked, and in a few instances I observed them forked. Others again had much the appearance of roots, having frequently holes as if branches had been broken out.
While in the rock their forms were sufficiently distinct; but they were so friable in their structure, that I could not detach pieces of any great length; and when so detached, they seldom conveyed the same idea. The appearance of the largest and finest specimens, therefore, which were imbedded in rocks of considerable magnitude, must be imagined from the drawings.
Notwithstanding that the resemblance of these forms to branches of trees was so striking that it was impossible not to imagine at first sight that this had been their origin, yet considering the difficulties attending the supposition that wood had been converted into sandstone, it seemed to me much more probable that they had been derived from some of those animals assuming a vegetable form and distinguished by the name of Zoophyte.