250 Some Account of the Island of Teneriffe, 



abrupt ridges, and is cut nearly perpendicular down to the sea, 

 I could not perceive anv base or shelf as on the other sides of 

 the Peak, from which the cone arose, but the fall is regular 

 though Pteep. From Puerto de los Clirhtianos to Santa Cruz, 

 com])rising the southern and south-eastern sides of the island, 

 the form is similar to that in the vicinity of Oroluva ; but it is 

 barren and desolate, laid waste by streams of lava. In the short 

 space of a few leagues I counted no less than seven cones of ex- 

 tinct volcanoes, and the country is covered with scoria, exhibit- 

 ing no appearance of culture, and hardly any of vegetation; it is 

 more broken into ravines and more intersected by lava torrents 

 than on any of the other sides of the island. Numerous peaked 

 and conical mountains rise upon the slope of the chain, and the 

 whole country is covered bv scoria, and is one continued stream 

 of lava. The Montana Uoxa itself is a singular examj)le of the 

 dislocation of strata so commonly found in countries of volcanic 

 formation ; it is evidently a slip or fall of semi-columnar lava, 

 and sIo])es into the sea at a highly inclined angle. 



The ordinary strata of the island are as follows, reckoning 

 from below upwards : 1st, the porphyritic lava covered by scoria 

 and sometimes by pumice. This lava is composed of hornblende 

 and feldspar, and contains no other substance. The next stra- 

 tum graduates into what the Spaniards call raccaverde or green- 

 stone, and is coni])osed of feldspar and hornbiende ; upon this is 

 generally a thick stratum of piunicc, and la&t of all towards the 

 surface is the basaltic lava covered also by tufa and ash. This 

 lava decomposes the soonest. It also contains the greatest 

 variety of extraneous substances, and is sometimes divided by a 

 layer of large crystals of olivine some inc-hes long, and towards 

 the north-east is often intersected by strata of porphyritic slate. 

 These lavas are more earthy and cellular than those which I have 

 had an opportuiiitv of observing elsewhere, yet they contain fewer 

 extraneous substances than those of /Etna and Vesuvius ; they 

 are in some places exposed to view in the vallevs similar to those 

 of the Corral m the island of Madeira. The valley of Lis 

 Gdianchas on the north-west side of the Peak, contains according 

 to M. Escolar* above 100 strata of lava, the one reposing upon 

 the other, at times alternating with ])umice and tufa. The 

 depth of these strata varies. M. Escolar has seen one of basaltic 

 lava between 100 and 130 feet in depth in one solid mass, cel- 

 lular at the surface, but gradually becoming more compact to- 



* M Escolar was sent out by tlie Spanish Government to exainine the 

 political, conimerciiil and ininciiilngical state oT tlie Canaries ; he has well 

 performed his tiisk,,iiid it is to be reiirettcd thnt the situation of his native 

 country has iiithcrto deprived tlie public of the intcrestnig facts he is able 

 lo coniiuuniciite. 



wdrds 



