ON ITS EXTERIOR. YOLC ANDES. 241 



crater (which now at its least-heated places is covered 

 with tufts of reed-like grasses, and of a Pourretia with 

 leaves resembling those of bromelias), that the eruptions 

 of burning scoriae, pumice, and ashes from the volcano 

 proceeded in 1539, 1560, 1566, 1577, 1580 and 1660. 

 The city of Quito was then often veiled for days in 

 thick darkness by the falling ashes. 



Of this more rare, elongated form of volcanoes, we 

 know, in the old world, Gralungung, with a large crater, 

 in the western part of Java ( 334 ), the doleritic mass of 

 the Schiwelutsch in the Kamtschatka, a chain whose 

 highest points attain 10,167 feet ( 335 ), and Hecla, which 

 seen from the north-west, or in the direction normal to 

 that of the principal longitudinal fissure over which it 

 was upheaved, presents a broad mountain ridge having 

 different small " horns " or summits. Since the most 

 recent eruptions, in 1845 and 1846, which gave a stream 

 of lava eight miles long and at some places two miles 

 broad, comparable to the stream of lava from Etna in 

 1669, there are on the back of Hecla five caldron- 

 shaped craters arranged in a row. As the principal 

 fissure is directed N. 65 E., the volcano, as seen from 

 Selsundfiall, i.e. from the south-west side, and therefore 

 as a cross section, appears a pointed cone. ( 336 ) 



If the shapes of volcanoes differ so strikingly from 

 each other, as Cotopaxi and Pichincha, without the 

 emitted substances and the chemical processes of the 

 profound interior being altered, the relative position of 

 the cones of elevation is sometimes yet more singular. 

 In Luzon, one of the Philippine Islands, the still active 

 volcano of Taal, whose most destructive eruption took 

 place in 1754, rises in the middle of a large lake in- 



YOL. IV. R, 



