CHAPTER 'IX. 



Origin of the newer Pliocene strata of Sicily Growth of submarine formations 

 gradual Rise of the same above the level of the sea probably caused by sub- 

 terranean lava Igneous newer Pliocene rocks, formed at great depths, exceed 

 in volume the lavas of Etna Probable structure of these recent subterranean 

 rocks Changes which they may have superinduced upon strata in contact 

 Alterations of the surface during and since the emergence of the newer Pliocene 

 strata Forms of the Sicilian valleys Sea cliffs Proofs of successive eleva- 

 tion Why the valleys in the newer Pliocene districts correspond in form to 

 those in regions of higher antiquity Migrations of animals and plants since 

 the emergence of the newer Pliocene strata Some species newer than the 

 stations they inhabit Recapitulation. 



ORIGIN OF THE NEWER PLIOCENE STRATA OF SICILY. 



HAVING in the last two chapters described the tertiary forma- 

 tions of the Val di Noto and Valdemone, both igneous and 

 aqueous, we shall now proceed more fully to consider their 

 origin, and the manner in which they may be supposed to have 

 assumed their present position. The consideration of this 

 subject may be naturally divided into three parts : first, we 

 shall inquire in what manner the submarine formations were 

 accumulated beneath the waters ; secondly, whether they 

 emerged slowly or suddenly, and what modifications in -the 

 earth's crust, at considerable depths below the surface, may be 

 indicated by their rise ; thirdly, the mutations which the sur- 

 face and its inhabitants have undergone during and since the 

 period of emergence. 



Growth of Submarine formations.' First, then 5 we are to 

 inquire in what manner the subaqueous masses, whether vol- 

 canic or sedimentary, may have been formed. On this subject 

 we have but few observations to make, for by reference to our 

 former volumes, the reader will learn how a single stratum, 

 whether of sand, clay, or limestone, may be thrown down at the 

 bottom of the sea, and how shells and other organic remains 



