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Updated: May 21, 2025
That was the only natural fuel on Ullr; there was too much silica on Ullr and not enough of anything else; what would be coal-seams on Terra were strata of silicified wood. And, of course, there was no petroleum.
Every geologist is aware how often silicified trees occur in volcanic tuffs, the perfect preservation of their internal structure showing that they have not decayed before the petrifying material was supplied. The porous and vesicular nature of a large part, both of the basaltic and trachytic lavas, affords cavities in which silex and carbonate of lime are readily deposited.
The plants called Sigillaria and Stigmaria, so marked a feature in the Carboniferous period, are as yet wanting in the true Permian. Among the remarkable fossils of the Rothliegendes, or lowest part of the Permian in Saxony and Bohemia, are the silicified trunks of tree-ferns called generically Psaronius.
In anatomical structure, the barks of the Syringodendrons are, then, analogous to those of the Sigillariæ. If, now, we compare the dimensions of the tissues of these barks with the same silicified tissues of the barks of Sigillariæ, we shall find that there was likewise a diminution in the dimensions, but yet a less pronounced one than in the woods that we have previously spoken of.
I was so much struck with this resemblance, that I particularly looked out for silicified wood, and found it under the following extraordinary circumstances.
Silicified fossil wood of a coniferous tree, is found abundantly in the plains, and in rounded pebbles in the banks and bed of the river, also chalcedony and compact brown haematite.
There is also much silicified wood, both common dicotyledonous and coniferous: a section of one specimen in the direction of the medullary rays has, as I am informed by Mr. R. Brown, the discs in a double row placed alternately, and not opposite as in the true Araucaria.
From this resemblance I expected to find silicified wood, which is generally characteristic of those formations. I was gratified in a very extraordinary manner. In the central part of the range, at an elevation of about seven thousand feet, I observed on a bare slope some snow-white projecting columns.
The sandstone contains fragments of wood, either in the state of lignite or partially silicified, sharks' teeth, and shells in great abundance, both high up and low down the sea-cliffs. Pectunculus and Oliva were most numerous in individuals, and next to them Turritella and Fusus. Gastridium cepa, G.B. Sowerby. 2. Monoceros, fragments of, considered by M. d'Orbigny as a new species. 3.
From this resemblance I expected to find silicified wood, which is generally characteristic of those formations. I was gratified in a very extraordinary manner. In the central part of the range, at an elevation of about seven thousand feet, I observed on a bare slope some snow-white projecting columns.
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