272 AXXUAL OF SCIENTIFIC DISCO VEliY. 



Association of Granite with Tertiary Strata. At a recent meet- 

 ing of the London Geological Society, Mr. J. G. Hawkins stated 

 the existence of a granitic formation in the Island of Jamaica, which 

 pierces both rocks of the carboniferous series, and also well character- 

 ized tertiary strata ; wherefore, IMr. H. has no doubt that the age of 

 the granite is tertiary. 



Volcanic Condition of Vesuvius. At the meeting of the British 

 Association, 1862, Dr. Daubeny stated that Vesuvius appears dar- 

 ing the last few years to have entered upon a new phase of action. 

 Its eruptions are more frequent but less violent than they were for- 

 merly ; they proceed from a lower level than they did at an earlier 

 period, and they give gaseous principles, such as the vapor of naph- 

 tha and light carburetted hydrogen, never before detected. The last 

 eruption caused an elevation of the coast to the height of three feet 

 seven inches above the level of the sea, which has not been observed 

 on any preceding occasion. Dr. Daubeny suggested that Vesuvius 

 was passing into the condition of a mud volcano, the products issuing 

 from it being simply owing to the action of volcanic heat on the con- 

 tiguous beds of Appenine limestone containing bituminous matters ; 

 hence the carbonic acid and carburetted hydrogen and naphtha 

 vapor emitted, which were to be regarded as mere secondary pro- 

 ducts, to be distinguished from the muriatic and sulphurous vapors 

 indicating primary volcanic action. 



Influence of Water on Volcanic Action. In a paper recently read 

 before the French Academy, by M. Pissis, the author stated that it is 

 generally believed, in those districts of South America which are most 

 subject to earthquakes, that these disturbances occur during the rainy 

 season, and up to the period of drought. During twelve years of his 

 own residence on the spot this theory has held good, and the years of 

 most violent rain were distinguished by a greater number of earth- 

 quakes ; and he adds, that if we consider that during the wet season 

 the Andes are covered with a dense bed of snow, which is perpetually 

 melting from contact with the soil, it will be obvious that an extensive 

 infiltration must take place ; so, if there exist any fissures communicat- 

 ing with the interior, large qtiantities of water may be brought into 

 contact with incandescent matter, and thus occasion very powerful 

 disturbances. 



Age of ike Delta of the Mississippi. Messrs. Abbot and Hum- 

 ys, in their elaborate work on the Physics and Hydraulics of the 

 Mississippi, recently published by the United States Government, 

 assign four thousand four hundred years as the approximate age of the 

 Mississippi since it assumed its present condition of a delta-forming 

 river, and state their reasons for believing that it existed before this as 

 a clear stream. They consider that the original mouth of the Missis- 

 sippi was near the present efflux of Bayou Plaquemine, and that, con- 

 sequently, its advance into the Gulf has been about 220 miles. The 

 present rate of advance of the mouth is about 262 feet per annum, 

 which will not probably be exceeded hereafter. 



The Ancient North American Continent. Mr. E. Kull, of the 

 Geological Survey of Great Britain, is of the opinion that the source 

 of the sediments which compose the carboniferous rocks of Great Brit- 

 ain was in an ancient North Atlantic continent, for the existence of 



