TRUE VOLCANOES. 305 



is probably not to be ascribed to these. Fissures, caused 

 by folding in the trachytic mass, which has been elevated 

 whilst soft and only subsequently hardened, have probably 

 preceded all actions of erosion and the impulse of water. 

 But in those places where deep barrancos appeared in the 

 volcanic districts visited by me on the declivities of bell 

 shaped or conical mountains (en lasfaldas de los Cerros bar- 

 rancosos), no trace was to be detected of the regularity, or 

 radiate ramification with which we are made acquainted by 

 Junghuhn's works in the singular outlines of the volcanoes 

 of Java. 97 The greatest analogy with the form here re- 

 ferred to is presented by the phenomenon to which Leopold 

 von Buch, and the acute observer of volcanoes, Poulet 

 Scrope, have already directed attention, namely, that great 

 fissures almost always open at a right or obtuse angle from 

 the centre of the mountain, radiating (although undivided), 

 in accordance with the normal direction of the declivities, 

 but not transversely to them. 



The belief in the complete absence of lava-streams upon 

 the island of Java, 98 to which Leopold von Buch appeared to 



cate any chasm. But that the word barranca is connected with barro, 

 clay, soft, moist loam, and also road-scrapings, is doubtful. 



97 Lyell, Manual of Elementary Geology, 1855, chap, xxix, p. 497. 

 The most remarkable analogy with the phenomenon of regular rib- 

 bing in Java, is presented by the surface of the Mantle of the Somma 

 of Vesuvius, upon the seventy folds of which, an acute and accurate 

 observer, the astronomer Julius Schmidt, has thrown mv Jo. light (Die 

 Eruption des Vesuvs im Mai, 1855, s. 101 109). According to 

 Leopold von Buch, these valley-furrows are not originally rain-fur- 

 rows (fiumare), but consequences of cracking (folding, etoilement) dur- 

 ing the first upheaval of the volcano. The usually radial position 

 of the lateral eruptions in relation to the axis of the volcano, also 

 appears to be connected therewith (s. 129). 



93 " Obsidian, and consequently pumice-stones, are as rare in Java 

 as trachyte itself. Another very curious fact is the absence of any 

 stream of lava in that volcanic island. M. Reinwardt, who has him- 

 self observed a great number of eruptions, says expressly that 

 there havn never been instances of the most violent and destructive 

 eruption having been accompanied by lavas." Leopold de Buch, 

 Descr. des lies Canaries, p. 419. Amongst the volcanic rocks of Java, 

 for which the Cabinet of Minerals at Berlin is indebted to Dr. Juug- 

 huhn, dioritic-trachytes are most distinctly recognizable at Burung- 

 agung, s. 255 of the Leidner catalogue, at Tjinas, s. 232, and in the 

 Gunung Parang, situated in the district Batu-gaugi. This is couse- 

 VOL. V. X 



