Mr. BEi!iNET on ihe Island of Tcncr iff c. 289 



long, and towards the north-east is often intersected by strata of por- 

 phyritic slate. These lavas are more earthy and cellular than those 

 which I have had an opportunity of observing elsewhere, yet they 

 contain fewer extraneous substances than those of iEtna and Vesuvius ; 

 they are in some places exposed to view in the vallies similar to those 

 qf the Corral in the island of Madeira. The valley of Las Guanchas 

 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 pumice and tufa. The depth of these strata varies . 

 M. Escolar has seen one of basaltic lava between 100 and 150 

 feet in depth in one solid mass, cellular at the surface, but gradually 

 becoming more compact towards the bottom. This basaltic lava con- 

 tains olivine and hornblende, and, in the caves on the coast, zeolite. 

 This substance is also found in stalactites and in masses, sometimes 

 in layers spread between the strata and diffused over the rock. 



Nodules of chalcedony are sometimes also found, but these sub- 

 stances occur only in the chain of mountains towards the north-east, 

 from the northern extremity of Santa Cruz to the point of Hidalgo. 



The lavas of the island are of an endless variety, and the number 

 of streams that have flowed are much beyond all enumeration. The 

 whole surface is either ash, or solid or decomposed lava, which seems 

 again and again to have been perforated by volcanic eruptions ; the 

 number of small extinct volcanoes is prodigious, they are to be found 

 in all parts of the island, but the stream that has flowed from even 

 the largest of them, such as the lava of the Peak called el Mai Paisy 

 is trifling in comparison with that immense mass of lava mountains 



* M. Escolar was sent out by the Spanish government to examine the political, com- 

 mercial and mineralogical state of the Canaries; he has well performed his task, and it is 

 to be regretted that the situation of his native country has hitherto deprived the public of 

 the interesting facts he is able to communicate. 



Vol. II. 2 o 



