GEOLOGY. 263 



that, at the commencement of the earth's histoiy, the various sub- 

 stances in ignition reacted on each other: " The quartz, which 

 is present in such a great proportion in many rocks, would de- 

 compose the carbonates and sulphates, and, aided by the presence 

 of water, the chlorides both of the rocky strata and of the sea ; 

 while the organic mattei's and the fossil carbon would be burned 

 by the atmospheric oxygen. From these reactions would result a 

 fused mass of silicates of alumina, alkalies, lime, magnesia, iron- 

 oxide, etc. ; while all the carbon, sulphur, and chlorine, in the 

 form of acid gases, mixed with watery vapor, nitrogen, and a 

 probable excess of oxygen, would form an exceedingly dense at- 

 mosphere. When the cooling pei*mitted condensation, an acid 

 rain would fall upon the heated surface of the earth, decompos- 

 ing the silicates, and giving i-ise to chlorides and sulj)hates of the 

 various bases, while the separated silica might take the form of 

 crystalline quartz. In the next stage of the iJi'ocess, the portions 

 of the primitive crust not covered by the ocean would undergo a 

 decomiDosition, under the influence of hot moist atmosphere 

 charged with carbonic acid, and the felspathic silicates become 

 converted into clay, Avith separation of the alkali. This, absorb- 

 ing carbonic acid from the atmosphere, would find its way to 

 the sea, where, having first jirecipitated from its highly-heated 

 waters various metallic bases then held in solution, it would de- 

 compose the chloride of calcium, giving rise to chloride of sodi- 

 um on the one hand, and to carbonate of lime on the other." — 

 Canadian Naturalist, Vol. II., note 4. 



GNEISS WITH IIMPRESSION OF EQUISETUM. . 



In the Museum at Turin is a fragment of gneiss from an eiTatic 

 block, apparently from the Valteline, from the crystalline rocks 

 underlying the infra-liassic group of Sismonda, containing an im- 

 pression of an Equisetum. Sismonda regards this fossil as jDroof 

 of the metamorphic character of the fundamental gneiss of the 

 Alps, and as affording a fact bearing on the age of the vegetable 

 impi'cssions accompanying the anthracite-bearing beds of the 

 Western Alps. 



ERUPTION OF ETNA. 



M. Fouqu6, in " Les Mondes," April 6, 1865, wi'ites that at 

 half-past 10 p. m., January 21, 18G5, there was a severe earth- 

 quake, and immediately afterward the eruption commenced. It 

 bi'oke out at the north-east side of the mountain, 1,700 metres 

 above the sea, and 500 from the foot of the old cone of Fru- 

 mento ; in two or three days the lava had flowed 6 kilometres, 

 with a breadth of 3 to 4, and a thickness of 10 to 20. There are 

 7 craters. There are four kinds of fumaroles there ; the dry, on 

 the incandescent lava ; the acid, where the temperature is above 

 400° C. ; the alkaline, where the temperature is below this, but 

 mostly above 100° C. ; and the carbonic, in an old crater near by, 

 where there is the ordinary teraperatui-e. There was a remark- 



