186 
OLDER PLIOCENE PERIOD. 
[Ch. XIV. 
map. The greatest number of perfect cones are in the imme- 
diate neighbourhood of Olot, some of which are represented in 
the frontispiece, and the level plain on which that town 
stands has clearly been produced by the flowing down of many 
lava-streams from those hills into the bottom of a valley, 
probably once of considerable depth like those of the surround- 
ing country. 
In the frontispiece an attempt is made to represent by colours 
the different geological formations of which the country is 
composed. The blue line of mountains in the distance are the 
Pyrenees, which are to the north of the spectator, and consist 
of primary and ancient secondary rocks. In front of these are 
the secondary formations described in this chapter, coloured 
grey. Different shades of this colour are introduced, to express 
various distances. The flank of the hill, in the foreground, 
called Costa cle Pujou, is composed partly of secondary rocks 
and partly of volcanic, the red colour expressing lava and 
scoriae. 
The Fluvia, which passes near the town of Olot, has only 
cut to the depth of forty feet through the lavas of the plain 
before mentioned. The bed of the river is hard basalt, and at 
the bridge of Santa Madalena, are seen two distinct lava- 
currents, one above the other, separated by a horizontal bed 
of scoriae eight feet thick. 
In one place, to the south of Olot, the even surface of the 
plain is broken by a mound of lava, called the ' Bosque de 
Tosca,' the upper part of which is scoriaceous, and covered 
with enormous heaps of fragments of basalt more or less porous. 
Between the numerous hummocks thus formed, are deep cavi- 
ties, having the appearance of small craters. The whole precisely 
resembles some of the modern currents of Etna, or that of 
Come, near Clermont, the last of which, like the Bosque de 
Tosca, supports only a scanty vegetation. 
Most of the Catalonian volcanos are as entire as those in the 
neighbourhood of Naples, or on the flanks of Etna. One of 
these, figured in the frontispiece, called Montsacopa, is of a 
