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Ideal landscape of the London Clay Period. Reconstruction of scenery and conditions of the past. Photograph of a large oil painting by Mr. E. Marsden Wilson that was hung in the Geological Museum in Exhibition Road, London. It depicts an imaginary scene in the south-east of England at a date something like fifty million years ago, when the London Clay was being deposited as sediment.
Published as Plate II. London and the Thames Valley. British Regional Geology. By R.L. Sherlock. 3rd edition with some additions by R. Casey, S.C.A. Holmes and V. Wilson. p. 34-35 for a full description which follows:
- In the Geological Museum is a large oil painting by Mr. E. Marsden Wilson, here reproduced from a photograph as Plate II, showing an imaginary scene in the south-east of England at a date something like fifty million years ago, when the London Clay was being deposited as sediment. At that time the district was under the sea, for the whole area is either covered, or has been covered, by London Clay and this was deposited in the sea. The coast, however, was not far away and was probably low-lying, for there were no hard rocks exposed to make high ground. The character of the animals and plants found fossil, considered together, throws light on the geographical conditions and it is supposed that the site of the district was near the estuary of a large river. The probability that the water was salt is shown by the presence of shells of marine type found in the clay, but the proximity of the coast and of a river is shown by the presence of crocodiles.
- The climate under which any specific deposit was accumulated may often be deduced from a study of a contained fossil flora, provided a sufficient number of genera have been discovered. The London Clay has in fact yielded, in particular to Mrs. E. M. Reid and Miss M. E. J. Chandler, an ample flora, from the study of which they support the theory that the contemporary climate was that of a tropical rain-forest—a conclusion stated in their comprehensive description of the London Clay Flora published in 1933 by the Trustees of the British Museum (Natural History).
- These authors point out that in H. N. Moseley's Notes by a Naturalist on the "Challenger," published in 1892, a description of the detritus of the Ambernoh River of New Guinea reads as if it were the authentic record of conditions that had existed in the London Clay sea of the Sheppey district. Moseley says that various fruits and seeds, and other plant fragments, were abundant in the water, floating in the midst of small aggregations of floating timber. Among them were the seeds of littoral plants but in addition there were seeds of 40 to 50 inland species. Very small seeds were as abundant as large ones. Leaves were generally absent, having been sorted out, and deposited in the mud nearer the shore. This observation explains the absence of leaves among the numerous other plant remains at Sheppey.
- One of the most striking plants found fossil in the London Clay is a palm very much like the Nipa palm that now grows abundantly in the Sunderbunds, at the mouth of the Ganges, in India. The plant was described by Sir J. Hooker as a low, stemless palm, with pale yellow-green tufts of feathery leaves, bearing at she base of the leaves a great head of nuts. The fruits are about a foot in diameter and made up of closely packed seeds, each as large as a hen's egg, and these ripen in early winter. In Plate II a large mass of Nipa palm is seen above and to the right of the crocodiles. As the picture depicts a summer scene the fruits could not be shown. The seeds float on the water to considerable distances and germinate in the mud, and a number of them are shown near the Nipa on the brackish water, to the left of the crocodiles. There were also mangroves in the swamp.
- Another interesting plant is the Sabal palm. At the present time this grows in damp places and the fossil representatives are assumed to have had a similar habitat. The base of the trunk ends in a knob surrounded by a dense mass of contorted roots. Laurels and Acacia-like plants were common, while among the climbing plants were numerous vines.
- In the illustration, the ground to the left of the Sabal palms is sandy and at the bottom of the picture on the left side is a tangled mass of ferns. It is not known with certainty if grass existed in London Clay time and so the ferns, which are known to have lived then, have been shown covering the ground instead of grass. The tree in flower is a Magnolia, which now grows in Britain.
- The animals shown differ markedly from living types. The mammals c animals ' of everyday language) are of great interest because they show characters not now found together in the same animal. Primitive mammals are known to have existed as long ago as the Triassic period, but it was not until the giant reptiles had died out at the end of the Cretaceous period that mammals became the dominant land animals. Released from the danger of the carnivorous reptiles, they underwent rapid development. At the time of the formation of the London Clay some-of the mammals had already developed a good deal from the most primitive types, but they were nevertheless very odd-looking creatures from a present-day point of view.
- In the middle of the picture are three specimens of Coryphodon, which resembled in build and sometimes in size a hippopotamus. Those in the picture are about the size of a cow. The feet were shaped something like an elephant's and there were five toes on each foot. The Coryphodon had strong canine teeth to protect it from enemies and was an omnivorous feeder. The group of ungulates (hoofed mammals) to which it belongs, the Amblypoda, has no living descendants, but for a time, it was the most prominent group of ungulates.
- Hyracotherium, an animal about the size of a fox, is seen below the magnolia. It belonged to the order Perissodactyla (ungulates with an odd number of toes) which at present is represented only by tapirs, rhinoceroses and horses, but in the Eocene period included many forms. The Hyracotherium had teeth some thing like those of a pig (bunodont), the limbs were moderately long, and it had four toes on the front and three toes on the hind feet covered by hoofs. Not only was it the ancestor of the horse but it was not far modified from the ancestral form of all the Perissodactyla.
- Two kinds of birds are shown in the picture. The flying bird is Odontopteryx, a sea-bird about the size of a gannet. Its chief peculiarity was the presence of strongly serrated jaws which were probably covered by horn, and they enabled the bird to seize the fishes on which it lived. The other bird is Dasornis, of which little is known. The skull shows that the bird was large, and Sir R. Owen thought that it probably resembled an ostrich. The other animals are crocodiles which differed little from the living species.
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