104 NEWER PLIOCENE PERIOD. [Ch. IX. 



may become imbedded therein. He will also understand how 

 one sheet of lava, or bed of scoriae and volcanic sand, may be 

 spread out over a wide area, and how, at a subsequent period, 

 a second bed of sand, clay, or limestone, or a second lava- 

 stream may be superimposed, so that in the lapse of ages a 

 mountain mass may be produced. 



It is enough that we should behold a single course of bricks 

 or stones laid by the mason upon another, in order to compre- 

 hend how a massive edifice, such as the Colosseum at Rome, 

 was erected ; and we can have no difficulty in conceiving that 

 a sea, three hundred or four hundred fathoms deep, might be 

 filled up by sediment and lava, provided we admit an indefinite 

 lapse of ages for the accumulation of the materials. 



The sedimentary and volcanic masses of the newer Pliocene 

 era, which, in the Val di Noto, attain the thickness of two thou- 

 sand feet, are subdivided into a vast number of strata and lava- 

 streams, each of which were originally formed on the sub- 

 aqueous surface, just as the tuffs and lavas whereof sections 

 are laid open in the Val del Bove, were each in their turn ex- 

 ternal additions to the Etnean cone. 



It is also clear, that before any part of the mass of submarine 

 origin began to rise above the waters, the uppermost stratum 

 of the whole must have been deposited ; so that if the date of 

 the origin of these masses be comparatively recent, still more so 

 is the period of their rise above the level of the sea. 



Subaqueous formations how raised. In what manner, then, 

 and by what agency, did this rise of the subaqueous forma- 

 tions take place ? We have seen that since the commencement 

 of the present century, an immense tract of country in Cutch, 

 more than fifty miles long and sixteen broad, was permanently 

 upraised to the height of ten feet above its former position, 

 and the earthquake which accompanied this wonderful varia- 

 tion of level, is reported to have terminated by a volcanic 

 eruption at Bhooi. We have also seen*, that when the Monte 

 Nuovo was thrown up, in the year 1538, a large fissure ap- 



* Vol. i. chap. xi$. 



