PROCEEDINGS OF GEOLOGICAL SOCIETIES. 
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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 bub- 
bling 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 metre above the sea-level. 
2. " On the Eecent Eruption of Vesuvius." By M. Pierre de Tchiha- 
tchefF. TchihatchefF's observations were made at Torre del Greco and 
]N'aples 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.AV. 
line, at a distance of about 600 metres E.S.E. of the crater of 1794 ; and 
either on a prolongation of the old fissure, or on one parallel. The pheno- 
mena mentioned by Signor Palmieri were described by M. Tcliihatcheflf 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 disti'jguished from Calcareous 
Strata, with especial reference to the Carboniferous Eocks 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 lime^ 
stones in another. Upon these data he urged that the formation of limestone 
was distinct from the deposition of littoral, or clayey and sand}^ deposits. 
The limestones were of organic origin, and formed in the clear deeps of the 
sea, which those essentially rock-fo)"ming creatures the foraminifera, corals, 
etc., inhabited, but not necessarilj' 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 tlie 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. 
Shore. Sea-surface. The Deep. 
Fig. 1. — Primary Section of a Formation. 
Thus where the limestones were thickestj as a general rule the sandstones 
and clays were thinnest ; and vice versa, when there was a great develop- 
ment 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 
