368 



nite. Some of the slates and limestones, probably referable to the 

 transition period, contain organic remains at an elevation of 1 3,000 

 feet above the sea. In the eastern chain are sandstones and conglo- 

 merates, and associated felspathic rocks regularly bedded, and more 

 recent than the rocks of the western chain, being partly made up of 

 their debris. After much investigation Mr. Darwin convinced him- 

 self that these were of the same age with certain tertiary deposits of 

 Patagonia, Chiloe, and Conception, resembling them in mineral cha- 

 racter and in the lignite and fossil wood which they contain. In 

 one escarpment is seen a sandstone of this system in which there 

 is a wood of petrified trees in a vertical position, some of the trees 

 being perfectly silicified and of dicotyledonous wood, others con- 

 sisting of snow-white columns of coarsely crystallized carbonate of 

 lime. They appear to have formed a clump of trees which had 

 grown on lava and was then submerged, so that layers of fine sand- 

 stone were quietly deposited between the trunks. The enveloping 

 sandstone rests on lava, and is again covered by a bed of black au- 

 gitic lava about 1000 feet thick. Over this there are at least five 

 other grand alternations of similar rocks and aqueous deposits, 

 amounting in thickness to several thousand feet. The same sedi- 

 mentary strata, or the continuation of them, are not only altered by 

 granite, but are traversed by dikes of granite proceeding from the 

 mass, and also by numerous iTietallic veins of iron, copper, arsenic, 

 silver, and gold, all of which can be traced to the underlying gra- 

 nite. A gold mine has been worked close to the clump of silicified 

 trees. 



From these observations I am led to suspect that, as in some parts 

 of the Alps, the metamorphic structure has been assumed by strata 

 high up in the secondary series, so in the Andes the same structure 

 has been superinduced on certain tertiary deposits which have been 

 also penetrated by granitic and by metalliferous veins. 



Dr. Daubeny has analysed a new thermal spring discovered near 

 the town of Torre del Annunziata in the Bay of Naples, and he re- 

 fers the origin of nitrogen gas in this and other springs in the vol- 

 canic region of Naples and Mount Vultur to a process of subterra- 

 nean oxygenation analogous to combustion. In the excavations 

 made in volcanic tuff and lava near Torre del Annunziata for gain- 

 ing access to the spring, vestiges of walls and buildings with fresco 

 paintings, and other traces of human art were discovered, and vege- 

 table mould containing the stems of reeds, similar to those now 

 growing in the neighbourhood, and a fir and cypress tree in an up- 

 right position. The buildings must have been overwhelmed before 

 the soil existed on which the fir and the cypress grew, as this soil 

 was formed upon the materials which enveloped the town. 



Mr. H. E. Strickland and Mr. Hamilton have examined a cavity be- 

 low the level of the sea in Cephalonia adjoining the coast, into which 

 a constant stream of sea water is flowing, and has been flowing for 

 years. This singular phsenomenon had previously attracted the at- 

 tention of Mr. Martin and of Lord Nugent and others, some of 

 whom had speculated, like Mr. Strickland, on the probability of the 



