Some Account of the Lland of Teneriffe. 253 



dwindling in size, and of them all the Spanish broom alone at 

 length covers the ground. Leaving behind us this range of green 

 hills, the track still ascending leads for several hours across a 

 eteep and difficult mass of lava rock, broken here and there into 

 strange and fantastic forms, worn into deep ravines, and scantily 

 covered in places by a thin layer of yellow pumice. The surface 

 of the country, for miles and miles around, is one continuous 

 stream of lava ; the rents or ravines of which seem to be formed 

 partly by the torrents from the hills flowing for so many ages, 

 and partly from that tendency, characteristic of a lava current, 

 to keep itself up in embankments, and in its cooling process to 

 open out into those hollows which I have uniformly found in 

 every eruption of lava that I have had an oj)portunity of exami- 

 ning. This lava is cellular beyond any I have ever seen, is of a 

 clayey earthy porphvritic composition, and contains few, if any, 

 pieces of olivine, though here and there felspar in a semicrystal- 

 lized form. As we proceeded on our road, the hills on our left, 

 though broken at times in deep ravines, gradually rose in height 

 'till the summits were lost in those of the central chain, while on 

 our right we were rapidly gaining an elevation above the lower 

 range of the peak. This range forms one flank of the plain or 

 valley of Orotava, stretching from south-east to north-west, and 

 is broken into steep precipices, cut down in some jDlaces perpen- 

 dicular to the horizon, and called Las Horcas ; it joins the cen- 

 tral chain at the high elevation of the pumice plains, sweeps 

 down the side of the valley, and forms a headland near 200 feet 

 high projecting into the sea, some miles from Orotava : we tra- 

 versed this country an hour or two, till we reached the point of 

 intersection of las Horcas with the plains of pumice. On the 

 road are several small conical hills or mouths of extinct vol- 

 canoes, the decomposed lava on the edges of these craters having 

 a strong red ochreous tint ; by degrees the lava becomes more 

 and more covered by a small ash, and the masses or heaps of 

 pumice gradually increase, till the surface is completely con- 

 cealed. At length an immense undulated plain spreads itself 

 like a fan, on all sides, nearly as far as the eye can reach, and 

 this plain is bounded on the west south-west, and south south- 

 v/est, l)y the regions of the peak ; and on the east and nortli- 

 east by a range of steep perpendicular precipices and mountains, 

 many leagues in circumference, called by the Spaniards Las 

 Faldas. M. Escolar informed me that the wall could be traced 

 for many leagues, the whole circumference of which evidently 

 formed the side of an immense crater. This tract, called Las 

 CunaleSy contains, according to the same authority, twelve square 

 leagues. A? v.c entered this plain from the south-west, there 



are 



