In the account given, in 1821, by M. Alex. Brongniart of the coal-mine of Treuil, at St. Etienne, near Lyons, he states, that distinct horizontal strata of micaceous sandstone are traversed by vertical trunks of monocotyledonous vegetables, resembling bamboos or large Equiseta.[319-B] Since the consolidation of the stone, there has been here and there a sliding movement, which has broken the continuity of the stems, throwing the upper parts of them on one side, so that they are often not continuous with the lower.
From these appearances it was inferred that we have here the monuments of a submerged forest. I formerly objected to this conclusion, suggesting that, in that case, all the roots ought to have been found at one and the same level, and not scattered irregularly through the mass. I also imagined that the soil to which the roots were attached should have been different from the sandstone in which the trunks are enclosed. Having, however, seen calamites near Pictou, in Nova Scotia, buried at various heights in sandstone and in similar erect attitudes, I have now little doubt that M. Brongniart's view was correct. These plants seem to have grown on a sandy soil, liable to be flooded from time to time, and raised by new accessions of sediment, as may happen in swamps near the banks of a large river in its delta. Trees which delight in marshy grounds are not injured by being buried several feet deep at their base; and other trees are continually rising up from new soils, several feet above the level of the original foundation of the morass. In the banks of the Mississippi, when the water has fallen, I have seen sections of a similar deposit in which portions of the stumps of trees with their roots in situ appeared at many different heights.[320-A]
Fig. 370.
Section showing the erect position of fossil trees in coal sandstone at St. Etienne. (Alex. Brongniart.)
When I visited, in 1843, the quarries of Treuil above-mentioned, the fossil trees seen in [fig. 370.] were removed, but I obtained proofs of other forests of erect trees in the same coal-field.
Fig. 371.
