TRUE VOLCANOES. 323 



also in earlier times), eight different, small craters of erup- 

 tion, (bocche nuove) were formed, arranged upon a longitu- 

 dinal fissure ; they are the so-called parasitic cones of erup- 

 tion, which poured forth lava, and are even by this circum- 

 stance entirely distinct from the Hornitos of Jorullo. 

 " Your Hornitos," wrote Leopold von Buch to me, " are 

 not cones accumulated by erupted matters ; they have been 

 upheaved directly from the interior of the earth." The 

 production of the volcano of Jorullo itself was compared by 

 this great geologist with that of the Monte Nuovo in the 

 Phlegrsean fields. The same notion of the upheaval of six 

 volcanic mountains upon a longitudinal fissure forced itself 

 as the most probable upon Colonel Riano and the mining 

 commissary Fischer in 1789 (see ante, p. 313), upon myself 

 at the first glance in 1803, and upon Burkart in 1827. 

 With both the new mountains, produced in 1538 and 1759, 

 the same questions repeat themselves. Upon that of South- 

 ern Italy, the testimonies of Falconi, Pietro Griacomo di 

 Toledo, Francesco del Nero and Porzio, are circumstantial, 

 near the time of the catastrophe and prepared by educated 

 observers. The celebrated Porzio, who was the most 

 learned of these observers, says : "Magnus terrse tractus, 

 qui inter radices montis, quern Barbarum incolae appellant, 

 et mare juxta Avernum jacet, sese erigere videbatur et montis 

 subito nascentis figuram iinitari. Iste terras cumulus aperto 

 veluti ore magnos ignes evomuit, pumicesque et lapides, 

 cineresque." 15 



From the geognostic description here completed of the 

 volcano of Jorullo, we will pass to the more eastern parts 

 of Central Mexico (Anahuac). Unmistakeable lava-streams, 

 the principal mass of which is usually basaltic, have been 

 poured out by the peak of Orizaba according to the most recent, 



15 Porzio, Opera omnia, Med., Phil, et Mathem. in unum collect a, 

 1736: according to Dufre*noy, Memoires pour servir a une Description 

 Geologique de la France, t. iv, p. 272. All the genetic questions are 

 discussed very completely and with praiseworthy impartiality in the 

 9th edition of Sir Charles Lyell's Principles of Geology, 1853, p. 369. 

 Even Bouguer (Figure de la Terre, 1749, p. Ixvi) was not disinclined 

 to the idea of the upheaval of the volcano of Pichincha. He says : 

 " It is not impossible that the rock, which is burnt and black, may 

 have been elevated by the action of subterranean fire." See also 

 p. xci. 



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