[61]The exceptional instance, of the accumulation on the land of blown sand imbedding the broken remains of marine shells, needs only to be noticed here.
[61]The exceptional instance, of the accumulation on the land of blown sand imbedding the broken remains of marine shells, needs only to be noticed here.
The fossils of Roman Camp Hill are not drifted specimens. They must have lived and died where the quarryman now finds them. We recognise them as all unequivocally marine; corals,crinoids, and brachiopodous molluscs, are all clearly the denizens of the sea, and hence we conclude that they mark the site of an ancient ocean. The snail-shells that swarm about the fruit-trees of our orchards not more unmistakably indicate a land-surface than do these petrified relics evidence an old sea-bottom. We can argue, too, from the crowded way in which they lie grouped together, that life must have been prolific in these primeval waters. Every fragment of the rock shows its dozens, nay, hundreds, of stone-lily joints, disjointed indeed, yet easily recognisable. They must have swarmed as thickly along the floor of the sea as the strong-stemmed tangle that darkens the bottom of many a picturesque bay along our western coasts, yet with a gracefulness of outline such as none of our larger sea-weeds can boast. Less numerous but not less markedlyin situare the shells of productus and spirifer, the former with its finely-striated surface fresh as if the creature had died but yesterday, while the slender spines with which it was armed lie strewed around. In short, the whole suite of organisms points to a period of tranquil deposition in a sea of probably no great depth, where the lower forms of the animal kingdom flourished in abundance, contributing by their calcareous secretions to form continuous layers of limestone.
Such a condition of things finds a parallel in many parts of the globe at the present day. Thus, the shores of the islands of the Pacific are white with fine calcareous mud, that results from the action of breakers on the surrounding coral-reefs. This mud, enveloping fragments of coral, shells, sea-weed, drift-wood, and other extraneous substances, hardens on exposure, and becomes eventually a limestone, travertine, or calc-sinter. We may believe that the same process goes on out at sea, around the edges of atolls or circular coral-reefs, and that the sediment thus thrown down will enclose any zoophytes or molluscan remains that may lie at the sea-bottom, along perhaps withfuci, and occasional water-logged fragments of wood that havebeen drifted from land. Along the shores of Guadaloupe a bed of this calcareous silt has formed since America was colonized by man, for it has been found to contain fragments of pottery, arrow-heads, and other articles of human workmanship.[62]The same rock has yielded, besides, the partially-petrified bones of several human skeletons, one of which, though without the head, forms a prominent object among the fossil treasures of the British Museum. The rock in which these remains are embedded is described as harder than statuary marble, notwithstanding its recent origin. By supposing the same process to be carried on over a large area and for a long period, we may see how a continuous stratum of limestone could be elaborated, full of fossil relics of corals, molluscs, and other marine productions. And in some such way, we may be permitted to believe, the seams of limestone on Roman Camp Hill were accumulated. The billows of that old carboniferous ocean may not have sent up their white surf against the margin of snowy coral-reefs, but the currents below did their work of demolition as effectually, and by sweeping through the submarine groves of stone-lilies and cup-corals, as the night winds of autumn sweep athwart the heavy-laden fields, would prostrate many a full-grown stem and scatter its loosened joints among the thickening lime that covered the bottom. Stone-lily, cup-coral, net-coral, productus, spirifer, pinna, nautilus, orthoceratite, all would eventually be entombed amid the decaying remains of their congeners, and thus produce a slowly-increasing seam of limestone.
[62]Lyell'sManual of Elementary Geology, p. 121. Fifth edition.
[62]Lyell'sManual of Elementary Geology, p. 121. Fifth edition.
We still linger in the old quarry on Roman Camp Hill, but the day draws rapidly to a close, and the long level beams of the setting sun lighten up the higher grounds with a golden flush, while the valley below lies deep in shade. The rays fall brightly on the abrupt face of limestone at the further end of the quarry, every prominence standing out in bold relief, andcasting its shadow far behind. Our eye, in passing over the sunlit rock, can detect the fractured joint of many an encrinite glancing in the light; along, too, with the strongly defined outlines of some of the lesser and more abundant molluscs—spirifers or producti. Some of them, sorely effaced by the rains, have begun to yield a scanty nestling place for creeping fibres of moss; others yet bare, afford a rest to theVanessawhereon to spread its wings in the mellow sunset ere flitting homewards among the dewy herbage. The bushes overhead scarcely rustle in the light-breathing air that comes fitfully across the land, and the long grass nods dreamily on the margin of the pool below. There rests a calm stillness on all the nearer landscape, and the distant ground blends away into the shades of evening. The scene, in short, has about it that solemn impressive repose which irresistibly arrests the fancy, and sets it to dress up into fantastic shapes the massive clouds that float in the western sky, to picture grim forms amid the misty shadows of the valley, or to dwell half dreaming upon the memories of the past, that come crowding through the mind in quick succession. Our labours among the fossils of the old quarry, however, enable fancy to draw her stores from another source. We muse on these petrified relics, gilded by the last rays of the setting sun, when slowly, like a dissolving view, sunset and herbage melt away, and the bottom of the old carboniferous ocean lies before us with its corals and shells and stone-lilies, stretching out their quivering arms, or expanding and contracting their flower-like petals amid a scene of ceaseless animation and activity. Geology delights in contrasts, and assuredly the contrast presented to us this evening between the present and the past of Roman Camp Hill, will not rank among the least striking of those which she has to reveal. There is now spread over us the blue sky, richly hung with tinted clouds, and melodious with the evening songs of the lark, the blackbird, and the thrush. Not less surely did a wide expanse of sea during the Carboniferous eraroll over the hill on which we stand. And yonder silvery moon that mounts up amid the violet twilight of the east, has witnessed each scene and all the countless changes that have intervened between them. The same pale light that now begins to steal through the woods and athwart the fields, must have streamed down upon that old sea and illumined its green depths. Oceans and continents, islands and lakes, hills and valleys, have come and gone with all their successive races of living things, and that same planet has marked them all. She has seen, too, as but a thing of yesterday, the appearance of man upon the scene, with all the successive centuries that have elapsed since then. Truly the "goddess of the silver bow" would have a strange story to tell us could we interrogate her about the past. But the days of Endymion have gone by, and she now no longer visits in a personal form the seat of beings who gaze at her crescent orb and daringly pronounce it a scene of blasted ruin and desolation.