124 



an animal of such bulk in frail canoes, without 

 recurring to the necessity of considering the 

 Guanches as a remnant of the people of the At- 

 lantis, or a different race from that of the west- 

 ern Africans. 



The hill, on which the town of San Christobal 

 de la Laguna is built, belongs to the system of 

 basaltic mountains, which, independent of the 

 system of less ancient volcanic rocks, form a 

 broad girdle around the peak of Teneriffe. The 

 basalt on which we walked was of a darkish 

 brown, compact, half decomposed, and exhaled, 

 when breathed on, a clayey smell. We disco- 

 vered hornblende, olivine *, and translucid py- 

 roxenes with a perfectly lamellar fracture, of 

 a tender olive green, and often crystallized in 

 prisms of six planes. The first of these substan- 

 ces is extremely rare at Teneriffe ; and I never 

 found it in the lavas of Vesuvius ; those of Etna 

 alone contain it in abundance. Notwithstand- 

 ing the great number of blocks, which we stop- 

 ped to break, to the great regret of our guides, 

 we could discover neither nepheline, nor leucitej, 

 nor feldspath. This, which is so common in the 

 basaltic lavas of the island of Ischia, does not 

 begin to appear at Teneriffe, till we approach the 

 volcano. The rock of Laguna is not columnar, 



* Peridot granuliforme. Hauy. 

 t Augit. Werner. 

 % Amphigene. Hauy. 



