Summit of the Peak of Tenerijfe in February 1829. 25 



posed lava and vegetable mould, to the depth of three feet; 

 next is a sort of volcanic breccia or conglomerate, held to- 

 gether by a brown mud and tufa ; afterwards a bed of volcanic 

 tufa, of four or five feet in thickness, succeeded by alternate 

 strata of compact bluish-coloured basaltic trap and brown 

 mud. In the bed of the ravine were large blocks of lava 

 mixed with hornblende and augite. 



In my first ascent to the Peak I was much disappointed 

 in not meeting with the forest of pine-trees above the zone of 

 chestnuts, which the visitors to the Peak during the last cen- 

 tury mention with so much pleasure ; but the destructive axe 

 has not left a single trace of them. On the way towards the 

 defile of the Portillo, there are several spots pointed out as 

 famous for the enormous size of a particular pine-tree, such 

 as Pino del Domajito, Pino de la Caravela, Pino de la Meri- 

 ejida, and Ultimo Pino. 



A short distance above Dornajito the surface is intersected 

 by numerous small ravines, and the soil is so thin that the 

 lava frequently appears above the surface. Ascending a little 

 further we approached the lower region of the clouds, where 

 we found the temperature begin to fall rather rapidly ; but at 

 the same time vegetation became so luxuriant, that it was 

 difficult to observe the nature of the lavas. The tree heaths 

 {Erica arborea) are of considerable size, being sometimes six- 

 teen or eighteen feet high, with stems half the thickness of a 

 man's body ; they are mixed with the laurel, cytisus, and va- 

 rious other arborescent shrubs : it is worthy of remark, that 

 all the leaves of the different shrubs here are of the same size, 

 form and colour, which is a brilliant dark green. This strong 

 vegetation is certainly produced by the humidity of the at- 

 mosphere, from the clouds generally resting at this elevation 

 during the night and early part of the morning. 



What makes this more evident is, that as you advance to 

 the verge of this climate, where the air is drier and the sun's 

 rays more powerful, vegetation becomes less luxuriant, and 

 the leaves are of a light green instead of a dark green co- 

 lour. 



The lavas here appeared to have flowed in numerous 

 streams from various openings; they look like a sort of wacken: 

 their colour is black, rather vesicular, and they contain green- 

 coloured augite, hornblende, and olivine, and all affect the 

 magnetic needle strongly. Many of the lavas are much de- 

 composed, with the pores on the outside free from crystals, 

 which have no doubt fallen out, as I always found them 

 internally. 



N. S. Vol. 8. No. 43. July 1 830. E We 



