100 



OLDER PLIOCENE PERIOD. 



[Ch. XIV. 



B (No. 46) 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 original current, 



No. 46. 

 A 



Section at Castell Follit. 



A, Church and town of Castell Follit, overlooking precipices of basalt. 



B, Small island, on each side of which branches of the river Teronel flow to 



meet the Fluvia. 



c, Precipice of basaltic lava, chiefly columnar. 



d, Ancient alluvium underlying the lava-current^ 



e, Inclined strata of secondary sandstone. 



From an examination of the vertical cliffs, it appears that 

 the upper part of the lava ori which the town is built is 

 scoriaceous, passing downwards into a spheroidal basalt ; some 

 of the huge spheroids being no less than six feet in diameter. 

 Below this is a more compact basalt with crystals of olivine. 

 There are in all about four distinct ranges of prismatic basalt, 

 separated by thinner beds not columnar, and some of which 

 are schistose. The whole mass rests on alluvium, ten or 

 twelve 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 



