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 conejomerate 
contains pebbles of quartz, limestone, and Lydian stone. The 
limestone is not only replete with nummulites, 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 Amer, 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 
