372 Geological Society. 



M. Necker objects to the earthquake in Calabria, in 1783, being 

 cousidered of true volcanic origin, because it was unaccompanied by 

 an)' disengagement of heat, lava, smoke, acid, or sulphureous pro- 

 ducts ; because the surface of the ground was depressed, not ele- 

 vated ; because only sand and water were ejected through the fis- 

 sures and circular or star-like cavities formed in the ground, and be- 

 cause there was no eruption of Vesuvius or Etna. The earthquakes 

 in the valley of the Mississippi, during 1812, he conceives were 

 non-volcanic, in consequence of no lava ha^dng been poured forth, 

 nor any acid or other vapours emitted. He alluded to a letter by 

 Mr. Stanley Griswold, dated Kaskahia, Illinois, the 22nd of Dec, 

 1812, which describes some of the phenomena of the earthquakes, — 

 particularly the subterranean noises resembling thunder, the cracks 

 formed in the ground, the issuing of " a something" like smoke, or 

 warm aqueous vapour, accompanied by a great quantity of sand, 

 the ejection of carbonised wood, coal, and pumice, a quantity of 

 which is said to have been collected on the Mississippi, the drying 

 up of lakes, and the raising of the bed of the river. To some of 

 these statements M. Necker objects. He conceives that the smoke, 

 or warm aqueous vapour, which is mentioned onljr from the reports 

 of others, and not decidedly, may have been mistaken for vapour 

 produced by water striking against an immoveable obstacle. The 

 occurrence of pumice, he conceives, is very doubtful ; and, as it is 

 mentioned by no other author, he withholds his assent till the sub- 

 stance has been examined by a competent mineralogist. 



M. Necker dissents from the Cutch earthquake in June, 1819, 

 being considered volcanic. The elevation of the UUah Bund, he 

 conceives, was effected by the subsidence of the ground towards 

 Sindree, or to a movement on a fixed axis. The materials thrown 

 out by the shocks were only black mud, sand, wrought iron, and 

 nails, and could not therefore, he says, have been produced from 

 any great depth. 



The earthquakes on the coast of Cumana, and the Caraccas, M. 

 Necker considers to be non-volcanic ; and that when the number and 

 violence of the shocks felt in that part of America are considered, he 

 is of opinion, that the agreement of the earthquakes, in April, 1812, 

 with the simultaneous eruption of the volcano of St. Vincent, was 

 purely fortuitous. 



In 1772, the little group, situated some leagues to the north of 

 the chain of the Caucasus, and composed of the trachytic moun- 

 tains called Pechstein, and the calcareous hill Metschuka, was 

 shaken by an earthquake. The warm springs, known by the name 

 of the baths of the Caucasus, issue from the foot of the limestone 

 hill, and deposit, as well as all the cold brooks, considerable quanti- 

 ties of calcareous tuiF. It might be supposed, observes M. Necker, 

 that the thermal springs indicate the existence of some portion of 

 the original heat of the trachyte ; and that the earthquake of 1772, 

 by which a portion of the hill, Metschuka, was engulphed, was only 

 the effect of volcanic activity. This, he says, is possible ; but it ap- 

 pears to him much more probable, that the cold and warm springs 



