324 COSMOS. 



of Pasto, between Maracndoy and the Cerro del Pulpito, 36 

 miles from the active volcano of Pasto. Leopold von Buch 

 has also called attention to a similar perfectly isolated erup- 

 tion of pumice-stone described by Meyen, which, consisting 

 of bo\vlders, forms a hill of 320 feet in height, near the vil- 

 lage of Tollo, to the east of Valparaiso, in Chili. The vol- 

 cano Maypo, which upheaves Jurassic strata in its rise, is two 

 full days' journey from this eruption of pumice-stone.* The 

 Prussian embassador in Washington, Friedrich von Gerolt, 

 to whom we are indebted for the first colored geognostic map 

 of Mexico, also mentions " a subterranean quarry of pumice- 

 stone at Bauten," near Huichapa, 32 miles to the southeast 

 of Queretaro, at a distance from all volcanoes, f The geo- 

 logical explorer of the Caucasus, Abich, is inclined to believe, 

 from his own observation, that the vast eruption of pumice- 

 stone near the village Tschegem, in the little Kabarda, on the 

 northern declivity of the central chain of the Elburuz, is, as 

 an effect of fissure, much older than the elevation of the very 

 distant conical mountain just mentioned. 



If, therefore, the volcanic activity of the earth, by radia- 

 tion of heat into space during the diminution of its original 

 temperature, and in the contraction of the superior cooling 

 strata, produces fissures and wrinkles (fractures et rides), and 

 therefore simultaneous sinking of the upper and upheaval of 

 the lower parts.}: we must naturally regard, as the measure 



* "The volcano of Maypo (S. lat. 34 15'), which has never ejected 

 pumice-stone, is at a distance of two clays' journey from the ridge of 

 Tollo, which is 320 feet in height, and entirely composed of pumice- 

 stone, inclosing vitreous feldspar, brown crystals of mica, and small 

 fragments of obsidian. It is, therefore, an (independent) isolated erup- 

 tion, quite at the foot of the Andes and close to the plain." Leop. de 

 Buch, Desc. Phys. des lies Canaries, 1830, p. 470. 



t Federico de Gerolt, Cartas Geognosticas de los Prindpales Distritos 

 Minerales de Mexico, 1827, p. 5. 



I On the solidification and formation of the crusts of the earth, see 

 Cosmos, vol. i., p. 172, 173. The experiments of Bischof, Charles De- 

 ville, and Delesse have thrown a new light upon the folding of the body 

 of the earth. See also the older, ingenious considerations of Babbage, 

 on the occasion of his thermic explanation of the problem presented 

 by the temple of Serapis to the north of Puzzuoli, in the Quarterly 

 Journal of the Geological Society of London, vol. iii., 1847, p. 186; 

 Charles Deville, Sur la Diminution de Densite dans les Roches en pas* 

 sant de titat cristallin a tetat vitreux, in the Comples rendus de tAcad. 

 des Sciences, t. xx., 1845, p. 1453 ; Delesse, Svr les Effets de la Fusion, 

 T. xxv., 1847. p. 455 ; Louis Frapolli, Sur la Caractere Geologique, in the 

 />//. de la Soc. Gcol. dej^rance, 2me. stirie, t. iv., 1847, p. 627; and, 

 above all, Elie de Beaumont, in his important work, Notice sur les Sys~ 



