THE CINDER CONE 



863 



cone is more typically convex. This is shown in the following 

 sketch of a cinder cone (Fig. 227) and appears further in Fig. 232. 



Monte Nuovo, in the Bay of Baie, near Naples, is an example of 

 a cone composed almost entirely of loose cinders. This volcano 

 had its birth within historic time, arising on the borders of the 

 ancient Lake Lucrinns on September 20, 1538, and attaining a 

 height of 440 feet. Other volcanoes largely composed of cinders 

 have arisen within the knowledge of man. Among them are Jorullo 

 (Mexico), 1759; Pochutla (Mexico), 1870; Camigiiin (Philippine 

 Islands), 1871 ; a new mountain of the Ajusco Mountain group 

 (Mexico), 1881 ; and the new mountain of Japan formed on Sep- 

 tember 9. 1910, and rising to a height of 690 feet. 



Both Jorullo and the new Camiguin volcano started from fissures 

 in level plains. The former arose in the night of September 28, 

 1759, 35 miles distant from any then existing volcano, and its sum- 



FiG. 227. Campo Bianco, in the 

 Island of Lipari. A pumice-cone, 

 breached by the outflow of an 

 obsidian lava stream. 



Fig. 228. Experimental illustration 

 of the mode of formation of vol- 

 canic cones composed of frag- 

 mental materials. (After Judd.) 



mit has since reached an elevation of 4.265 feet above sea-level. 

 The Camiguin volcano had a growth period of four years during 

 which it reached a height of about 1,800 feet. 



Consolidation of cinder cones. Unless extravasations of lava 

 should punctuate the eruptions of cinders, the cinder-cone is not 

 likely to be thoroughly consolidated, but remains rather in the con- 

 dition of an ash or sand heap. Diagenetic processes will, of course, 

 go on throughout the mass and thus consolidation may be brought 

 about, aided by the metamorphosing efifect of the steam and hot 

 vapors accompanying each eruption, and penetrating more or less 

 through the mass of accumulated material ( atmo-metamorphism). 



Stibtnarine Explosive Eruptions. Explosive eruptions are prob- 

 ably as common in the littoral belts of the sea as they are on land, 

 and, indeed, near the margins of the lands they, in common with the 

 extravasative eruptions, may be more frequent than elsewhere, as 

 discussed beyond. There is no reason for doubting that explosive 

 eruptions also occur on the floor of the deeper sea — though exam- 



