672 VOLCANOES OF CATALONIA. [Ch. XXXI 



open its internal structure in a precipice about 130 feet in "height, 

 at the edge of which stands the town of Castell Follit. 



By the junction of the rivers Fluvia and Teronel, the mass of lava 

 has been cut away on two sides ; and the insular rock b (fig. 722) 

 has been left, which was probably never so high as the cliff a, as it 

 may have constituted the lower part of the sloping side of the origi- 

 nal current. 



From an examination of the vertical cliffs, it appears that the 

 upper part of the lava on which the town is built is scoriaceous, pass- 

 ing downwards into a spheroidal basalt; some of the huge spheroids 

 being no less than 6 feet in diameter. Below this is a more compact 

 basalt, with crystals of olivine. There are in all five distinct ranges 

 of basalt, the uppermost spheroidal, and the rest prismatic, separated 

 by thinner beds not columnar, and some of which are schistose. 

 These were probably formed by successive flows of lava, whether 

 during the same eruption or at different periods. The whole mass 

 rests on alluvium, 10 or 12 feet in thickness, composed of pebbles of 

 limestone and quartz, but without any intermixture of igneous rocks; 

 in which circumstance alone it appears to differ from the modern 

 gravel of the Fluvia. 



Bufadors. — The volcanic rocks near Olot have often a cavernous 

 structure, like some of the lavas of Etna ; and in many parts of the 

 hill of Batet, in the environs of the town, the sound returned by the 

 earth, when struck, is like that of an archway. At the base of the 

 same hill are the mouths of several subterranean caverns, about twelve 

 in number, called in the country " bufadors," from which a current of 

 cold air issues during summer, but in winter it is said to be scarcely 

 perceptible. I visited one of these bufadors in the beginning of 

 August, 1830, when the heat of the season was unusually intense, and 

 found a cold wind blowing from it, which may easily be explained ; 

 for as the external air, when rarefied by heat, ascends, the pressure of 

 the colder and heavier air of the caverns in the interior of the moun- 

 tain causes it to rush out to supply its place. 



In regard to the age of these Spanish volcanoes, attempts have been 

 made to prove, that in this country, as well as in Auvergne and the 

 Eifel, the earliest inhabitants were eye-witnesses to the volcanic 

 action. In the year 1421, it is said, when Olot was destroyed by an 

 earthquake, an eruption broke out near Amer, and consumed the 

 town. The researches of Bon Francisco Bolos have, I think, shown, 

 in the most satisfactory manner, that there is no good historical foun- 

 dation for the latter part of this story ; and any geologist who has visit- 

 ed Amer must be convinced that there never was any eruption on that 

 spot. It is true that in the year above mentioned, the whole of Olot, 

 with the exception of a single house, was cast down by an earthquake ; 

 one of those shocks which, at distant intervals during the last five 

 centuries, have shaken the Pyrenees, and particularly the country be- 

 tween Perpignan and Olot, where the movements, at the period alluded 

 to, were most violent. 



