TRUE VOLCANOES. 273 



ations whose old eruptions belong to historic periods, or of 

 which the structure and eruptive masses (craters of elevation 



Volcano of Aconcagua,* W.N.W. of Mendoza, lat. 32 39' ; alti- 

 tude 23,004 feet, according to Kellet (see p. 241, note); but, ac- 

 cording to the most recent trigonometric measurement of the 

 engineer Amado Pissis (1854), only 21,301 feet; consequently, 

 rather lower than the Sahama, which Pentland now assumes to 

 be 22,350 feet (Gilliss, United States Naval Astron. Exped. to Chili, 

 vol. i., p. 13). The geodetic basis of measurement of Aconca- 

 gua at 6797 metres, which required eight triangles, has been de- 

 veloped by M. Pissis, in the Anales de la Universidad de Chile. 

 1852, p. 219. 



The peak of Tupungato is stated by Gilliss to be 22,450 English, or 

 21,063 Paris, feet in height, and in lat. 33 22' ; but in the map 

 of the province of Santiago, by Pissis (Gilliss, p. 45), it is esti- 

 mated at 22,016 English, or 20,655 Paris, feet. The latter num- 

 ber is retained (as 6710 metres) by Pissis in the Anales de Chile. 

 1850, p. 12. 



(6.) Between the parallels of Valparaiso and Concepcion: 



Volcano of Maypu* according to Gilliss (vol. i., p. 13), in lat. 34 

 17' (but in his general map of Chili, 33 47', certainly errone- 

 ously), and 17,662 feet in height. Ascended by Meyen. The 

 trachytic rock of the summit has broken through upper Jurassic 

 strata, in which Leopold von Buch detected Exogyra Couloni, 

 Trigonia costata, and Ammonites biplex, from elevations of 9600 

 feet (Description Physique des lies Canaries, 1836, p. 471). No 

 lava streams, but eruptions of flame and scorise from the crater. 



Volcano of Peteroa,* to the east of Talca, in lat. 34 53' ; a volca- 

 no which is frequently in activity, and which, according to Moli- 

 na's description, had a great eruption on the 3d December, 1762. 

 It was visited in 1831 by the highly-gifted naturalist, Gay. 



Volcan de Chilian, lat 36 2' ; a region which has been described by 

 the missionary Havestadt, of Miinster. In its vicinity is situated 

 the Nevado Descabezado (35 1'), which was ascended by Do- 

 meyko, and. which Molina declared (erroneously) to be the high- 

 est mountain of Chili. Its height has been estimated by Gilliss 

 at 13,100 feet (United States Naval Astr. Exped., 1855, vol. i., 

 p. 16 and 371). 



Volcano of Tucapel, to the west of the city of Concepcion ; also 

 called Silla Veluda : perhaps an unopened trachytic mountain, 

 which is in connection with the active volcano of Antuco. 



(c.) Between the parallels of Concepcion and Valdivia : 



Volcano of Antuco,* lat. 37 7' ; geognostically described in detail 

 by Poppig; a basaltic crater of elevation, from the interior of 

 which a trachytic cone ascends, with lava streams, which break 

 out at the foot of the cone, and more rarely from the crater at 

 the summit (Poppig, Reise in Chile and Peru,bd. i., s. 364). One 

 of these streams was still flowing in the year 1828. The inde- 

 fatigable Domeyko found the volcano in full activity in 1845, and 

 its height only 8920 feet (Pentland, in Mary Somerville's Phys- 

 ical Geography, vol. i., p. 186). Gilliss states the height at 9242 

 M2 



