Читать книгу The Palace and Park - Edward Winslow Forbes - Страница 54

From our stand on the Grand Plateau, which is fifty feet in width, we obtain a general view of a tract of several acres of ground occupied by Geological illustrations, and including a number of islands partly covered by strange figures, the restored forms of various animals which for many ages have ceased to exist as living tribes.

[27] See “Handbook to the Extinct Animals and Geological Illustrations described,” by Professor Owen.

The wonders of geology are not confined to grand mountain chains piercing the clouds, burning mountains vomiting steam and hot ashes, and vast accumulations of animal and vegetable remains found imbedded everywhere around us. They extend to facts connected with the structure of the earth’s crust, the existence of stores of mineral wealth, and strange results derived from the comparison of existing races with the fragments of other races formerly occupying the surface. The form of the surface depends on the internal structure; the scenery is due to the circumstances of the prevailing rock and soil; and the sea-cliff and naked mountain side are the places where nature teaches her first great lesson of the natural history of the Mineral Kingdom. To illustrate geology, it was necessary to perform the same kind of task as that which has been so successfully performed in the Architectural Courts, and the result is now before the visitor, as he looks down from this plateau and prepares to enter on the new course of investigation open to him. The ground forming the cliffs, shores, banks, and islands in this part of the Park are so constructed as to give, in a series of views, a number of practical lessons in geology, tending to make the essential facts of the science easily understood, while, at the same time, they add to the picturesque beauty of the scenery. The plan may be recognised in the fine expanse of cliff now at our feet; to do justice to which we must descend and place ourselves on the tongue of land below, or on the rustic bridge a little to the left. From hence may be seen the full length of the present cliff, and a few words of explanation will be sufficient to indicate the succession of rocks and the geological phenomena.

On this cliff, the part immediately facing the bridge represents a section nearly vertical of part of a coal-field, all the beds dipping (or inclining) at a moderate angle to the right-hand, so that those to the left are lower in geological position, though they gradually become higher in point of actual elevation, and at a little distance further to the left overtop the coal itself. Besides this illustration, we also see in the same equal part of the cliff instances of faults or troubles, throwing a part of the coal-measures into a different position from the rest, and lifting up portions of a series of deposits. In the case before us, the older rocks are also thrown up on the left side of the fault.

The coal-cliff consists of two beds or seams of coal, two of ironstone, and some sandstone. The part not consisting of projecting stone is supposed to represent softer rocks, clays, or shales. There are placed here about twenty-five tons of coal, twenty tons of grit or sandstone, and five tons of ironstone, all from the neighbourhood of Clay Cross.

In order to produce a marked contrast, the carboniferous limestone is placed next in order, and as if brought up to its position by a considerable fault. The millstone grit, appearing on the top of the plateau above the limestone, would have occupied naturally and without disturbance, a position below the lowest part of the coal measures. The fault is therefore called, technically, an upthrow or upcast to the south. The millstone grit consists of about 30 tons of rock from Crick, near Matlock, and from Bramley Fall quarries, in Yorkshire. The carboniferous limestone (of which there is 100 tons) is from the neighbourhood of Matlock, and is placed nearly in its natural position.

In this cliff of carboniferous limestone the bedding may be very distinctly traced, and systems of fissures, or joints, may also be observed. One of these fissures, wider than the rest and communicating with several smaller ones, is partly filled with spar, and has an opening into a cavern constructed behind the cliff. The main fissure represents a mineral vein or lode, and the smaller ones are strings or feeders. Within the cavern the spectator sees some of the peculiar and interesting appearances of natural limestone grottoes.

Coming out below the limestone, hard beds of the old red sandstone are seen. These have the same dip as the limestones, and are seen at intervals further to the left towards the railway. It is intended to continue the series of older and altered rocks in this direction. The old red sandstone on the ground consists of about twenty tons from near Bristol.

Overlying this whole series of old (or palæozoic) rocks, which are inclined to the north, is a horizontal, and therefore unconformable capping of new red sandstone. This also is from near Bristol, and the quantity provided was fifty tons.

The new red sandstone, thus capping the old rock on the high ground of the plateau, re-appears at the extremity of the nearest of the adjacent islands at a much lower level, and having a different mechanical position.

It is right to mention that these geological sketches are the result of careful consideration, and have not been effected without much constructive ingenuity. The original plan of the whole was suggested by Professor Ansted, and arranged with Sir Joseph Paxton at an early period of the laying out of the grounds; and as soon as the state of affairs permitted and the actual earthworks of the Plateau were in progress, a model of the intended structure was completed and coloured geologically by Professor Ansted. The works have been ably constructed from this model by Mr. James Campbell, who also procured the stone and other minerals from different parts of the country.

The Labyrinthodons.

Let us now return to the Plateau, from whence we can obtain the best view of the islands and their singular tenants. Before describing them, however, we will remind the visitor that the lowest or oldest rocks, which we have shown him, were the old red sandstone; next above them were the carboniferous limestone, the millstone grit, the coal-measures, and then the new red sandstone. It is with this last formation that the restorations of the extinct animals commence. Before that period fossil remains indicate that fish inhabited the waters of the earth, but there are no traces of the existence of any reptiles or higher animals. Reptiles first appear in the new red sandstone, and as the extreme right of the islands is arranged to represent this formation, it is there that we shall find the Labyrinthodon and the Dicynodon, of each of which there are two species. The strata which overlie the new red sandstone will be now mentioned in the order of their super-position, each successive formation bringing us nearer to the forms of animal life which are at present living upon the earth.

Next above the new red sandstone comes the lias, the general direction of the inclination of the beds being the same as in the coal-cliff, and the newer beds covering up the old ones as we advance in the direction of the larger islands. The lias animals are here represented by three very dissimilar forms; there are three species of Ichthyosaurus, or Fish Lizard; three species of Plesiosaurus, or Serpent Lizard, and a crocodilian beast called Teleosaurus, which much resembles the fish-eating Gavial of the river Ganges. This crocodile and the fish lizards formerly inhabited the neighbourhood of Whitby in Yorkshire, where their remains are found in good condition. Dr. Buckland describes the Plesiosaurus as the most singular and monstrous of the relics of the former world, having the head of a lizard, the teeth of a crocodile, a neck like the body of a serpent, the trunk and tail of an ordinary quadruped, the ribs of a chameleon, and the paddles of a whale.

The next formation in ascending order is the oolite. To this stratum, as well as to the succeeding one, belongs the Megalosaurus, or Gigantic Lizard, which measures 39 feet from snout to top of tail, and 22 feet 6 inches round the body, and the smaller Pterodactyles.

Still proceeding to the left, we pass next to the Wealden formation so well known in Kent, Surrey, and Sussex. Here we see the gigantic Iguanodons, and the Hylæosaurus, or Great Spiny Lizard of the Wealden. It is with these creatures that the name of the late distinguished palæontologist, Dr. Mantell, will ever be connected, since to his labours in Tilgate Forest and other parts we are indebted for our knowledge of these animals.

Above the Wealden formation come those of the lower greensand and the chalk. Both of these also contain fragments of singular reptiles of large size, the Mosasaurus and great Pterodactyles (most probably the fabled dragon of old) restored from Mr. Bowerbank’s specimens.

With these we quit the Secondary Island, and may next turn our attention to the island beyond, which contains the principal forms characterising the strata belonging to the tertiary period. Hitherto we have shown the visitor nothing but reptiles—now, upon the Tertiary Island, he will find a higher order of animal life, and meet with forms more nearly resembling our living animals. Next in procession are the animals restored by Baron Cuvier from fragments found in the Gypsum beds of the Paris basin: the Palæotherium, or Ancient Beast, might be justly called the first triumph of comparative anatomy, as from a few detached pieces of bone Cuvier was enabled to construct the entire animal, which, by his drawings, appears to have resembled the Tapir of the present day. After these come the more elegant pachydermatous animal called the Anoplotherium commune and the Anoplotherium gracilis, and not far off we see the Megatherium, or Gigantic Sloth, in the act of pulling down a tree to obtain the leaves, upon which it was accustomed to feed, as its smaller analogies do at the present day. These, with the Irish Elks, first found in the Isle of Man, are grouped upon this island, and present a scene equally remarkable and instructive to all those who are interested in the natural history of the earlier periods of the earth.