PROCEEDINGS OE GEOLOaiOAL SOCTETTES. 



93 



tory on Yesuvius. 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 Recent Eruption of Yesuvms." By M. Pierre de Tchiha- 

 tcheff. M. 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 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. 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 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 tliatof 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 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. 



store. Sea-surface. The Deep. 



Pig. 1. — Primary Section of a Formation. 



Thus where the limestones were thickest, as a genei'al 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 



