CANARY ISLANDS. 81 



lofty range of mountains which encircle the Peak, and 

 extend tliemselves towards Lagjuna, and la Punta de Naga, 

 their highest pinnacle being elevated about 9000 feet above 

 the level of the ocean. They appear to be composed prin- 

 cipally of basaltes of more recent origin than those of the 

 lower stratum, but they contain a variety of other sub- 

 stances. Near La Punta de Naga are found zeolites, and 

 a greater portion of their highest pinnacles near La Agua 

 Mansa, is composed of ferruginous sand which appears to 

 have withstood the action of fire. Just on the borders of 

 El Llano de Gaspas, we meet with large masses of very 

 ancient basaltes which contains some distinct impressions 

 of ferns. On the southern side of this range of moun- 

 tains, m El Valle de Ucanca, there is found an abund- 

 ance of feldspathic lava, and near by, at La Agua Agria 

 are large beds of talcose slate. And in the same range 

 on the eastern side of El Valle de Santiago, there 

 occurs an abundance of pyroxenic lava containing olivine, 

 and in a deep stratum of yellowish earth resembling tufa, 

 there are found millions of crystals of pyroxene of a very 

 large size, and a variety of forms. But whether these 

 substances found on the southern side of the mountains 

 are the products of the present volcano, it is difficult to 

 determine. 



This range of mountains, and the products of the present 

 volcano, are separated by strata of tufa, puzzolana, and 

 other disintegrated lavas. A beautiful variety of the 

 former occurs on the northern side of the mountain near 

 El Valle de Ucanca. The currents of lava that I met with 

 on the slopes of these mountains, were black masses, par- 

 tially decomposed, and often cellular, having oblong pores. 

 Their basis is wacke, and when porous, they resemble 

 amygdaloid. Their fracture is irregular, and in some 

 instances, conchoidal. They are not divided into regular 

 columns, but occur in very thin layers irregularly inclined. 

 They contain a considerable quantity of olivine, small 

 grains of magnetic iron, and augites, the color of the latter 

 varying from a deep green to an olive tint. 



Next in succession above the tufas, etc., comes the 

 great elevated llano of Las Canadas, which contains about 

 ten square leagues, and is composed principally of small 



