United States or British Indian Ocean Territory ? Vote for the TOP Country of the Week !
In the Department of the Hautes Alpes, in France, M. Eliede Beaumont traced a black argillaceous limestone, charged with belemnites, to within a few yards of a mass of granite. Here the limestone begins to put on a granular texture, but is extremely fine-grained. When nearer the junction it becomes grey, and has a saccharoid structure.
Any limestone which is sufficiently hard to take a fine polish is called MARBLE. Many of these are fossiliferous; but statuary marble, which is also called saccharoid limestone, as having a texture resembling that of loaf-sugar, is devoid of fossils, and is in many cases a member of the metamorphic series.
Their substance is formed of the shells of the common oyster in bluish gray and black particles on a white ground, as in the Lumachella d' Egitto; of the cardium or cockle, assuming a lighter or deeper shade of yellow, as in the Lumachella d' Astracane; of the ammonite, as in the L. Corno d' Ammone; of the Anomia ampulla in the L. occhio di Pavone, so called from the circular form of the fossils whichever way the section is made; of encrinites, belemnites, and starfish, showing white or red on a violet ground, as in the L. pavonazza; and "of broken shells, hardly discernible, together with very shining and saccharoid particles of carbonate of lime," as in the Marmor Schiston of the ancients the brocatello antico of the Italians, so named from its various shades of yellow and purple, resembling silk brocade.
Paul de Fenouillet, the chalky limestone becomes more crystalline and saccharoid as it approaches the granite, and loses all trace of the fossils which it previously contained in abundance. At some points, also, it becomes dolomitic, and filled with small veins of carbonate of iron, and spots of red iron-ore.
Word Of The Day