532 



YOLCANOS OF CATALONIA. 



[Oh. XXXL 



the adjoining map gives a correct view of the true area of the volcanio 

 action. 



Geological structure of the district. — The eruptions have burst entirely 

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

 sandstone and conglomerate, with some thick beds of nummulitic lime- 

 stone. The conglomerate contains pebbles of quartz, limestone, and 

 Lydian stone. This system of rocks is veiy extensively spread throughout 

 Catalonia ; one of its members being a red sandstone, to whieh the cele- 

 brated salt-rock of Cardona, usually considered 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, primary 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 Janks, 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 pre- 

 vails through the whole area described in the map, the inclination of 

 the beds being sometimes at an angle of between 40 and 50 degrees. 



It is evident that the physical geography of the country has under- 

 gone no material change since the commencement of the era of the 

 volcanic eruptions, except such as has resulted from the introduction of 

 new hills of scoriae, and currents of lava upon the surface. If the lavas 

 could be remelted and poured out again from their respective craters, 

 they would descend the same valleys in which they are now seen, and 

 re-occupy the spaces which they at present fill. The only difference in 

 the external configuration of the fresh lavas would consist in this, that 

 they would nowhere be intersected by ravines, or exhibit marks of ero- 

 sion by running water. 



Fig. 667. 



View of the Volcanos around Olot in Catalonia. 



