Ch. XIV.] VOLCANOS OF CATALONIA. 185 



Geological structure of the district. The eruptions have 

 burst entirely through secondary rocks, composed in great 

 part of grey and greenish sandstone and conglomerate, with 

 some thick beds of nummulitic limestone. The conglomerate 

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

 limestone is not only replete with nummulit.es, but occasionally 

 includes oysters, pectens, and other shells. This system of 

 rocks is very extensively spread throughout Catalonia, one of 

 its members being a red sandstone, to which the celebrated 

 salt-rock of Cardona is subordinate. It is conjectured that 

 the whole belongs to the age of our green-sand and chalk. 



Near Araer, in the Valley of the Ter, on the southern bor- 

 ders 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 

 secondary strata from their flanks, causing them to dip to the 

 north and north-west. This dip, which is towards the 

 Pyrenees, is connected with a distinct axis of elevation, and 

 prevails 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 

 undergone 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 reoccupy 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 erosion by running water. 



Volcanic cones and lavas. There are about fourteen distinct 

 cones with craters in this part of Spain, besides several points 

 whence lavas may have issued ; all of them arranged along a 

 narrow line running north and south, as will be seen in the 



