bed of the Rhine near Cologne in Germany, by the Valley of Ronca in the territory of Verona, by the Pont de Bridon in the State of Venice, and by numerous other examples in the same country. A corresponding effect is produced on a small scale on the southern declivity of Arthur Seat, near Edinburgh, where the hill overhangs the Lake of Duddingstone; and numerous other instances are known to occur in the islands which lie between the coast of Ireland and Norway, as well as Spain, Portugal, Arabia, and India. When these crystals have obtained a certain regularity of structure, the form is often hexagonal, or six-sided, resembling particular kinds of spar, and the emerald. Patrin, during his travels in the deserts of Oriental Tartary, discovered when breaking the Asiatic emerald, if fresh taken from the matrix, not only the same alternate concave and convex fractures which sometimes characterize the horizontal fissures of basaltic pillars, but also the concentric layers which denote concretionary formation. It is hardly possible to have a more striking proof of coincidence, resulting from similarity of structure, in two substances otherwise remarkably distinguished from each other. In this state science remains at present, concerning an appearance in nature which exhibits nothing more than the common process of crystallization upon a larger scale than has usually excited attention. Suffice it to remark, that such a phenomenon is very frequent in the vicinity of very ancient lakes, in the bed of all considerable rivers, or by the borders of the ocean.* In a country where there are so many traces of volcanic action, the rocks of the lower levels cannot fail to bear marks of their origin. Hasselquist relates, that the Hill of Tiberias, out of which issues the fountain whence the baths are supplied, consists of a black and brittle sulphurous stone, which is only to be found in large masses in that neighbourhood, though it is commonly met with in rolled specimens on the shores of the Dead Sea, and in other parts of the valley. The sediment deposited by the water is also black, as thick as paste, smells strongly of sulphur, and is covered with two skins or cuticles, of which the lower is of a fine dark-green, and the uppermost of a light rusty colour. At the mouth of the outlet, where the stream formed little cascades over the stones, the first cuticle alone was found, and so much resembled a conferva, that one might have taken it for a vegetable production; but nearer the river, where the current became stagnant, both skins were visible, the yellow on the surface, and under it the green.* There are observed, in the same hollow, small portions of quartz incrusted with an impure salt, and nodules of clay extremely compact. Near the edge of the valley there lie scattered on the sand considerable portions of flinty slate; and amid the common clay, which forms the basis of the soil, are perpendicular layers of a lamellated brown argil, assuming, as it were, the slaty structure. Dr Clarke noticed among the pebbles near the Lake of Tiberias pieces of a porous rock resembling the substance called toadstone in England; its cavities were filled * Hasselquist's Voyages and Travels, p. 284. with zeolite. Native gold was likewise found there, but the quantity was so small, as not to draw from the travellers a suitable degree of attention. The Vale of the Asphaltites is farther remarkable for a species of limestone called the fetid, the smell of which, as its name imports, is extremely offensive. It is still manufactured in the East into amulets, and worn as a specific against the plague; and that a similar superstition existed in regard to this stone in very early ages is rendered manifest by the circumstance, that charms made of the same substance were found in the subterranean chambers under the pyramids of Sakhara in Upper Egypt. The cause of the fetid effluvia emitted from this rock, when partially decomposed by means of friction, is now known to be connected with the presence of sulphuretted hydrogen. All bituminous limestone, however, does not possess this property. It is not uncommon in the calcareous beds called in England black marble, but it is by no means their characteristic. The fragments obtained in the Valley of the Jordan have this savour in a high degree; and it is admitted that the oriental limestone is more highly impregnated with hydro-sulphuret than any hitherto found in Europe.* According to Dr Shaw, the upper strata of rocks on the hills along the coast are composed of a soft chalky substance, including a great variety of corals, shells, and other marine exuviæ. Upon the Cas travan Mountains, near Beirout, there is a singular bed, consisting likewise of a whitish stone, but of the slate-kind, which unfolds in every flake of it a Clarke's Travels, vol. iv. pp. 223 and 307. In a country where there are so many traces of volcanic action, the rocks of the lower levels cannot fail to bear marks of their origin. Hasselquist relates, that the Hill of Tiberias, out of which issues the fountain whence the baths are supplied, consists of a black and brittle sulphurous stone, which is only to be found in large masses in that neighbourhood, though it is commonly met with in rolled specimens on the shores of the Dead Sea, and in other parts of the valley. The sediment deposited by the water is also black, as thick as paste, smells strongly of sulphur, and is covered with two skins or cuticles, of which the lower is of a fine dark-green, and the uppermost of a light rusty colour. At the mouth of the outlet, where the stream formed little cascades over the stones, the first cuticle alone was found, and so much resembled a conferva, that one might have taken it for a vegetable production; but nearer the river, where the current became stagnant, both skins were visible, the yellow on the surface, and under it the green.* There are observed, in the same hollow, small portions of quartz incrusted with an impure salt, and nodules of clay extremely compact. Near the edge of the valley there lie scattered on the sand considerable portions of flinty slate; and amid the common clay, which forms the basis of the soil, are perpendicular layers of a lamellated brown argil, assuming, as it were, the slaty structure. Dr Clarke noticed among the pebbles near the Lake of Tiberias pieces of a porous rock resembling the substance called toadstone in England; its cavities were filled * Hasselquist's Voyages and Travels, p. 284. with zeolite. Native gold was likewise found there, but the quantity was so small, as not to draw from the travellers a suitable degree of attention. The Vale of the Asphaltites is farther remarkable for a species of limestone called the fetid, the smell of which, as its name imports, is extremely offensive. It is still manufactured in the East into amulets, and worn as a specific against the plague; and that a similar superstition existed in regard to this stone in very early ages is rendered manifest by the circumstance, that charms made of the same substance were found in the subterranean chambers under the pyramids of Sakhara in Upper Egypt. The cause of the fetid effluvia emitted from this rock, when partially decomposed by means of friction, is now known to be connected with the presence of sulphuretted hydrogen. All bituminous limestone, however, does not possess this property. It is not uncommon in the calcareous beds called in England black marble, but it is by no means their characteristic. The fragments obtained in the Valley of the Jordan have this savour in a high degree; and it is admitted that the oriental limestone is more highly impregnated with hydro-sulphuret than any hitherto found in Europe.* According to Dr Shaw, the upper strata of rocks on the hills along the coast are composed of a soft chalky substance, including a great variety of corals, shells, and other marine exuviæ. Upon the Castravan Mountains, near Beirout, there is a singular bed, consisting likewise of a whitish stone, but of the slate-kind, which unfolds in every flake of it a * Clarke's Travels, vol. iv. pp. 223 and 307. |