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 with _fuci_, and occasional water-logged fragments of wood that have been 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. [Footnote 62: Lyell's _Manual of Elementary Geology_, p. 121. Fifth edition.]