Ch. XXXI.] 



PLIOCENE VOLCANOES. 



661 



scriptiou, tlie volcanic region extended over twenty square leagues, 

 from Amer to Massanet. I searched in vain in the environs of Has- 

 san et in the Pyrenees for traces of a lava-current ; and I can say with 

 confidence, that the adjoining map gives a correct view of the true 

 area of the volcanic action. 



Fie. Tib. 



Volcanic district of Catalonia. 



Geological Structure of the District. — The eruptions have burst en- 

 tirely through fossiliferous rocks, composed in great part of gray and 

 greenish sandstone and conglomerate, with some thick beds of num- 

 mulitic limestone. The conglomerate contains pebbles of quartz, 

 limestone, and Lydian stone. This system of rocks is very exten- 

 sively spread throughout Catalonia ; one of its members being a red 

 sandstone, to which the celebrated salt-rock of Cardona, usually con- 

 sidered as of the cretaceous era, is subordinate. 



Near Amer, in the Valley of the Ter, on the southern borders of 

 the region delineated in the map, crystalline rocks are seen, consisting 

 of gneiss, mica-schist, and clay-slate. They run in a line nearly 

 parallel to the Pyrenees, and throw off the fossiliferous strata from 

 their flanks, causing them to dip to the north and northwest. This 

 dip, which is towards the Pyrenees, is connected with a distinct axis 

 of elevation, and prevails through the whole area described in the 



