218 cosmos. 



are not decidedly disinclined to all classifications, because in 

 the endeavor after generalization these always rest only upon 

 imperfect indications, we may conceive the bursting forth of 

 fused masses and solid matter, vapors and gases, in four dif- 

 ferent ways. Proceeding from the simple to the complex 

 phenomena., we may first mention eruptions from fissures, 

 not forming separate series of cones, but producing volcanic 

 rocks superlying each other, in a fused and viscid state; 

 secondly, eruptions through heaped-up cones, without any cir- 

 cumvallation, and yet emitting streams of lava, as was the 

 case for five years during the destruction of the island of 

 Lancerote, in the first half of the last century ; thirdly, cra- 

 ters of elevation, with upheaved strata, but without central 

 cones, emitting streams of lava only on the outside of the 

 circumvallation, never from the interior, which is soon closed 

 up with detritus ; fourthly, closed bell-shaped mountains or 

 cones of elevation, open at the summit, either inclosed by a 

 circular wall, which is at least partially retained — as on the 

 Pic of Teneriffe, in Fogo, and Rocca Monfina ; or entirely 

 without circumvallation or crater of elevation — as in Ice- 

 land,* in the Cordilleras of Quito, and the central parts of 

 Mexico. The open cones of elevation of this fourth class 

 maintain a permanent connection between the fiery interior 

 of the earth and the atmosphere, which is more or less effect- 

 ive at undetermined intervals of time. Of the dome-shaped 

 and bell-shaped trachytic and doleritic mountains which have 

 remained closed at the summit, there appear, according to 

 my observations, to be more than of the open cones, whether 

 active or extinct, and far more than of the true volcanoes. 

 Dome-shaped and bell-shaped mountains, such as Chimbora- 

 zo, Puy de Dome, Sarcouy, Rocca Monfina, and Vultur, give 

 the landscape a peculiar character, by which they contrast 

 pleasingly with the schistose peaks, or the serrated forms of 

 limestone. 



In the tradition preserved to us so picturesquely by Ovid 

 regarding the great volcanic phenomenon of the peninsula of 

 Methone, the production of such a bell-shaped and unopen- 

 ed mountain is indicated with methodical clearness. " The 

 force of the winds imprisoned in dark caves of the earth, and 

 seeking in vain for an opening, drive up the heaving soil 

 {extentam tumefecit humum), as when one fills a bladder or 

 leather bag with air. By gradual hardening the high pro- 



* Sartorius von Waltershausen, Physisch-geographische Skizze von 

 Island, 1847, s. 107. 



