21. The plants forming coal have grown in the basin where the coal is found; but sandstone rocks in the coal-measures deposited by water having a considerable velocity, and consequently carrying power, contain sometimes trunks of large trees which have been drifted like snags.
22. The strata between the Permian epoch and Chalk display numerous Gymnosperms, especially belonging to the Cycadaceous Order. Some of them exhibit limited coal deposits.
23. The Chalk and Tertiary strata display not only Acrogens and Gymnosperms, but also Angiospermous Dicotyledons, some of which, at the Miocene period, belong apparently to genera of the present day.
24. Brown Coal occurs in the Upper Tertiary beds, and in it vegetable structure is easily seen under the microscope.
25. Raulin thinks that during the Tertiary epoch the flora of Europe has gradually assumed a more temperate character.
26. The Eocene flora, according to Unger, resembled in many respects that of Australia at the present day.
27. The Miocene flora is characterised by a number of exotic forms of warm regions with those of temperate climates. It is largely seen in the Arctic Regions.
28. The Pliocene flora has great analogy with that of the temperate regions of Europe, North America, and Japan.