26 Mr. Alison's Narrative of an Excursio7i to the 



We still gradually ascended ; and as we crossed Barranco 

 Haya we were rather annoyed by the lower region of clouds 

 condensing on our clothes and bodies, and producing by 

 the evaporation a degree of cold considerably greater than 

 that indicated by the thermometer, which was 49*5 ; we like- 

 wise encountered a strong current of air blowing from the 

 west-by-south, although both above and below us the wind 

 was blowing from the N.N.W. This current of air was pro- 

 duced probably by the wind sweeping down the western ex- 

 tremity of the mountain called Tigayga, into the entrance of 

 the Cafiadas, between the Cavison and the Portillo (which is 

 a sort of defile or opening in the chain of mountains that sur- 

 round the Cafiadas), thus creating a considerable pressure of 

 air, which caused a rush of wind into the valley below. 



Some distance above Barranco Haya we crossed an ancient 

 stream of lava, which appeared to have proceeded from a 

 volcano to the S.S.W., but it was so covered with vegetation 

 that it was difficult to discover its composition. The detached 

 pieces which I picked up were a porphyritic trachyte, with 

 crystals of augite and felspar, partly destroyed by fire. 



At j to 8 A.M. we crossed the ravine named Fuera el Monte, 

 and entered the Llanos de Gaspar (the plains of Gaspar). Here 

 vegetation became very scanty, and almost the only plant was 

 Canarian thyme. But this spot is particularly interesting, 

 from its being evident that a considerable part of the water- 

 spout which deluged the island in November 1826 had burst 

 here, cutting the surface into a vast number of ravines, 

 some of them of great depth. From the appearance of the 

 surface, the columns of water which fell must have been very 

 numerous ; as in ten or twelve different places the lava is cut 

 into deep trenches, some of them fifteen and twenty feet deep, 

 with the soil which was between them completely washed away 

 by the spray or overflowing of the water. Many of these deep 

 channels frequently converge into one, forming a destructive 

 and overwhelming ravine. 



Considerable bodies of water have frequently fallen upon the 

 Canaries, and done some mischief by washing into the sea the 

 vegetable mould which so thinly covers the lavas. But the 

 visitation of the 6th and 7th of November 1826 was the most 

 awful and destructive, both to life and property, of any 

 of which the inhabitants have any tradition. My friend Mr. 

 Auber, of Orotava, has furnished me with the interesting 

 details of the phenomena attending this waterspout, which I 

 shall here subjoin. 



On the afternoon of the 6th of November, the wind, which 



was 



