626 JAVA. [Cu. XXIX. 



crater was active, or how much by subsequent engulphmeut and de- 

 nudation. 



Java. — One of the latest contributions to our knowledge of vol- 

 canoes will be found in Dr. Junghuhn's work on Java, where forty- 

 six conical eminences of volcanic origin, varying in elevation from 

 4000 to nearly 12,000 feet above the sea, constitute the highest 

 peaks of a mountain range, running through the island from east to 

 west. All of them, with one exception, did this indefatigable traveller 

 survey and map. In none of them could he discover any marine re- 

 mains, whether adhering to their flanks or entering into their internal 

 structure, although strata of marine origin are met with nearer the sea 

 at lower levels. Dr. Junghuhn ascribes the origin of each volcano to 

 a succession of subaerial eruptions from one or more central vents, 

 whence scoriae, pumice, and fragments of rock were thrown out, and 

 whence have flowed streams of trachytic or basaltic lava. Such over- 

 flowings have been witnessed in modern times from the highest sum- 

 mits of several of the peaks. The external slope of each cone is gene- 

 rally greatest near its apex, where the volcanic strata have also the 

 steepest dip, sometimes attaining angles of 20, 30, and 35 degrees, 

 but becoming less and less inclined as they recede from the summit, 

 until, near their base, the dip is reduced to 10 and often to 4 or 5 

 degrees.* The interference of the lavas of adjoining volcanoes some- 

 times produces elevated platforms, or " saddles," in which the layers 

 of rock maybe very slightly inclined. At the top of many of the 

 loftiest mountains the active cone and crater are of small size, and 

 surrounded by a plain of ashes and sand, this plain being encircled in 

 its turn by what Dr. Junghuhn calls " the old crater-wall," which is 

 often 1000 feet and more in vertical height. There is sometimes a 

 terrace of intermediate height (as in the mountain called Tengger), 

 comparable to the "black ledge" of Kilauea (fig. 694). Most of the 

 spaces thus bounded by semicircular or more than semicircular ranges 

 of cliffs are vastly superior in dimensions to the area of any known 

 crater or hollow which has been observed in any part of the world to 

 be occupied by a lake of liquid lava. As the Spaniards have given to 

 such large cavities the name of Galdera (or cauldron), it may be use- 

 ful to use this term in a technical sense, whatever views we may 

 entertain as to their origin. Many of them in Java are no less than 

 four geographical miles in diameter, and they are attributed by Jung- 

 huhn to the truncation by explosion and subsidence of ancient cones 

 of eruption. Unfortunately, although several lofty cones have lost a 

 portion of their height within the memory of man, neither the inhab- 

 itants of Java nor their Dutch rulers have transmitted to us any reli- 

 able accounts of the order of events which occurred.f 



Dr. Junghuhn believes that Papandayang lost some portion of its 



* Java, deszelfs gedaante, bekleeding en hwendige structuur, door F. Junghuhn. 

 (German translation of 2d edit, by Hasskarl, Leipzig, 1852.) 

 f See Principles of Geol., 9th edit., p. 493. 



