NOTES ON JURASSIC FLORAS

Abstract

“What Nature has writ with her lusty wit Is worded so wisely and kindly That whoever has dipped in her manuscript Must up and follow her blindly.” W. E. Henley. My aim in these notes is to reconstruct in broad outlines a picture of the vegetation which flourished more than 100 million years ago over the lower part of this area at a time when rivers were building up broad deltas and spreading out sheets of sediment that were later to be upraised into headland and moor. In some places, where the water encroached over the land, the underground stems of Horsetails were preserved where they grew; in other places the wandering streams bore on their surface random samples of the vegetation collected from undermined banks or contributed by the wind. After taking a general survey of the Jurassic flora I shall briefly compare it with slightly older floras discovered in other parts of the world, and reference will be made to the old problem of the history and origin of the flowering plants. In order to facilitate description some liberties will be taken with the geological record: the rocks of East Yorkshire, usually spoken of as the Upper, Middle and Lower sub-divisions of the Estuarine Series, will be regarded as a single source of plant fossils, the fossils from which it is possible to form some general ideas of a Middle Jurassic delta-flora. The plant-bearing beds are freshwater or brackish sediments laid down in an area which, in the …