Page:The Geologist, volume 5.djvu/117

93 tory on Vesuvius. In letters addressed to H.M.'s Consul at Naples, and dated December 17tli, 1831, and January 3rd, 1862.

The author spoke of the evolution of great quantities of carbonic acid gas as seemingly coming from a great subterranean reservoir, and as bubbling up in the sea and killing the fish. He also noticed the outbursts of springs of acidulous, and hot water; and especially mentioned the upheaval of the ground for some miles along the shore at Torre del Greco to the height of more than a mètre above the sea-level.

2. "On the Eecent Eruption of Vesuvius." By M. Pierre de Tchihatcheff. Tchihatcheff's observations were made at Torre del Greco and Naples from December 8th to 25th. Near Torre del Greco several small craters (9–12) have been formed close to each other in an E.N.E.–W.S.W. line, at a distance of about 600 mètres E.S.E. of the crater of 1794; and either on a prolongation of the old fissure, or on one parallel. The phenomena mentioned by Signor Palmieri were described by M. Tchihatcheff in detail, who also alluded to the evolution of sulphuretted hydrogen, and suggested this as an explanation of the flames said to have emanated from the fissures in the ground at various places.

3. "On Isodiametric Lines as means of representing the Distribution of Sedimentary (clay and sandy Strata), as distinguished from Calcareous Strata, with especial reference to the Carboniferous Rocks of Britain." By E. Hull, E.G.S., of the Geological Survey of Great Britain.

The author exhibited maps of the Carboniferous rocks of England and Wales, and by means of coloured isodiametric lines showed the gradual thinning-out of the clays and sandstones in one direction, and that of the limestones in another. Upon these data he urged that the formation of limestone was distinct from the deposition of littoral, or clayey and sandy deposits. The limestones were of organic origin, and formed in the clear deeps of the sea, which those essentially rock-forming creatures the foraminifera, corals, etc., inhabited, but not necessarily formed in deep seas. Thus the condition of the strata beneath us was that of a series of overlapping wedges. The feather-edges of the clays and sands being in one direction, and those of the limestones in the other—the former thinning out from the shore into the sea, the latter proceeding from the bottom of the sea and terminating towards the shore.

Thus where the limestones were thickest, as a general rule the sandstones and clays were thinnest; and vice versâ, when there was a great development of clays and sands the limestones were usually thin.

The author made a comparison of argillaceo-arenaceous with calcareous deposits, as to their distribution, both in modern and in ancient seas, and objected to calcareous strata being regarded as sediments, in the strict sense of the word. Noticing the distribution of sediments, in the Caribbean Sea, he referred to the relative distribution of limestones as compared with shales and sandstones in the Oolitic formations (comparing those of Yorkshire with those of Oxfordshire), in the Permian strata of England, and in the Lower Carboniferous strata of Belgium and Westphalia. After some observations