Ch. XIV.] VOLCANOS OF THE KIFKL. 193 



quakes, nor subjected to the action of any great transient flood 

 since their origin. 



East of Olot, on the Catalonian coast, marine tertiary strata 

 occur, which, near Barcelona, attain the height of about 500 

 feet. It appears probable, from a small number of shells which 

 I collected, that these strata may correspond with the Sub- 

 apennine beds, so that if the volcanic district had extended 

 thus far, we might be able to determine the age of the igneous 

 products, by observing their relation to these older Pliocene 

 formations *. 



Sardinian volcanos. The line of extinct volcanos in Sar- 

 dinia, described by Captain Smyth f , is also of uncertain date, 

 as, notwithstanding the freshness of some of the cones and lavas, 

 they may be of high antiquity. They rest, however, on a ter- 

 tiary formation, supposed by some to correspond to the Sub- 

 apennine strata, but of which the fossil remains have not been 

 fully described. 



VOLCANIC ROCKS OF THE EIFEL. 



The volcanos of the Lower Rhine and the Eifel are of no less 

 uncertain date than those of Catalonia ; but we are desirous of 

 pointing out some of their peculiar characters, and shall, 

 therefore, treat of them in this chapter, trusting that future 

 investigations will determine their chronological relations more 

 accurately. 



For the geographical details of this volcanic region, we refer 

 the reader to the annexed map, for which I am indebted to 

 Mr. Leonard Horner, whose residence in the country has 

 enabled him to verify the maps of MM. Noeggerath and Von 

 Oyenhausen, from which that now given has been principally 

 compiled. 



* For some account of the Olot volcanos see ' Noticia de Los Esiinguidos 

 Volcanes de la Villa de Olot,' by Francisco Bolos. Barcelona. No date, but the 

 observations, I am told, preceded those of Dr. Maclure. 



f Present state of Sardinia, &c., pp. 69, 70. 



VOL. III. O 



