CONTENTS. 



CHAPTER IV. 



PAGE 



Chronological relations of mineral masses the first object in geological 

 classification Superposition, proof of more recent origin Exceptions in re- 

 gard to volcanic rocks Relative age proved by included fragments of older 

 rocks Proofs of contemporaneous origin derived from mineral characters 

 Variations to which these characters are liable Recurrence of distinct rocks 

 at successive periods Proofs of contemporaneous origin derived from organic 

 remains Zoological provinces are of limited extent, yet spread over wider 

 areas than homogeneous mineral deposits Different modes whereby dis- 

 similar mineral masses and distinct groups of species may be proved to have 

 been contemporaneous ...... -T> 



CHAPTER V. 



Classification of tertiary formations in chronological order Comparative 

 value of different classes of organic remains Fossil remains of teistacea the 

 most important Necessity of accurately determining species Tables of shells 

 by M. Deshayes Four subdivisions of the Tertiary epoch Recent for- 

 mations Newer Pliocene period Older Pliocene period Miocene period 



Eocene period The distinct zoological characters of these periods may not 



imply sudden changes in the animate creation The recent strata form a 

 common point of departure in distant regions Numerical proportion of 

 recent species of shells in different tertiary periods Mammiferous remains 

 of the successive tertiary eras Synoptical Table of Recent and Tertiary 

 formations ....... 



CHAPTER VI. 



Newer Pliocene formations Reasons for considering in the first place the 

 more modern periods Geological structure of Sicily Formations of the 

 Val di Noto of newer Pliocene period Divisible into three groups Great 

 limestone Schistose and arenaceous limestone Ulue marl with shells 

 Strata subjacent to the above Volcanic rocks of the Val di Noto Dikes 

 TuIIs and Peperinos Volcanic conglomerates Proofs of long intervals 

 between volcanic eruptions Dip and direction of newer Pliocene strata 

 of Sicily . ..... f,'2 



CHAPTER VII. 



Marine and volcanic formations at the base of Etna Their connexion 

 with the strata of tin: Val di Noto Day of TiT/./a Cycloplan islis l-'us.-il 

 bhulls of Rceut species Basalt and alteicd rocks in the Isle of ('\cL.ps 



