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Show XX CONTENTS, CHAPTER IV. PAGR Chronological relations of mineral masses the first object in geological classification-Superposition, proof of more recent origin-Exceptions in regard to volcanic rocks-Relative age proved by included fragments of older roclts-Proofs of contemporaneous origin derived from mineral charactersVariations 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 e~tent, yet spread over wider areas than homogeneous mineral deposits-Different modes whereby dissimilar mineral masses and distinct groups of species may be proved to have been contemporaneous CHAPTER V. Classification of tertiary formations in chronological order-Comparative value of different classes of organic remains-Fossil remains of testucea the most important-Necessity of accurately determining species-Tables of shells by M. Deshayes-Four subdivisions of the Tertiary epoch-Recent formations- Newer Pliocene period-Older Pliocene period-Miocene perio(l -Eocene period-The distinct zoological characters of these perious 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 &hells in different tertiary perio<ls-Mammiferous remains of the successive tertiary era.s-Synoptical Table of Recent and Tertiary 35 formations 45 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 anti arenaceous limestone-Blue marl with shellsStrata suujaccut to the above-Volcanic rocks of the Val di Note-DikesTuff..; anti Pepcriuos-Volcanic conglomerates-Proofs of long intervals between volcanic eruptions-Dip anti direction of newer Pliocene strata of Sicily 62 CHAPTER VII. Marine and volcanic formations at the base of Etna-Their connexion with the strata of the Val di Noto-Bay of Trezza-Cyclopian isl!!s-Fossil shells of recent species-Basalt anu altered rocl<s in thu Isle of Cyclops- CONTENTS, xxi PAGE Submarine lavas of the bay of Trezza not currents from Etua-Internal structure of the cone of Etna-Val di Calanna-Val tiel Bove not an ancient crater-Its precipices intersected by countless dikes-Scenery of the Val del Bove-Form, composition, anti origin of the dikes-Lavas and breccias intersected by them 75 CHAPTER VIII. Speculations on the origin of the Val del Bove on Etna-SubsiuencesAntiquity of the cone of Etna-Mode of computing the ago of volcanosTheh growth analogous to that of exogenous trees-Period requireu for the J>roduction of the lateral cone!! of Etna-Whether signs of Diluvial Waves are observable ou Etna 95 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 subterranean lava-Igneous newer Pliocene rocks formed at great depths, exceeu in volume the lavas of Etna-Probable structure of these recent subtenanean rocks-Changes which they may have superiutiucecl upon ~trata in contact-Alterations of the surface during and since the emergence of the newer Plioc~ne strata-Forms of the Sicilian valleys-Sea cliffs-Proofs of successive elevation-Why the valleys in the newer Pliocene uistricts correspond in form to those in regions of higher antiquity-Migrations of animals and plants since the emergence of the newer Pliocene shuta-Some Sllecies older than the stations they inhabit-Recapitulation 103 CHAPTER X. Tertia1·y formations of Campania-Comparison of the recorded changes in this region with those commemorated hy geological monuments-Differences in the composition of Somma and Vesuvius-Dikes of Somma, their origin -Cause of the parallelism of their opposite sides-Why coarser grained in the centre-Minor cones of the Phlegrroan Fields-Age of the volcanic and associateu rocks of Campania-Organic remains-External configuration of the country, how p1·ouuced-No signs of diluvial waves-Marine Newer Pliocene strata visible only in countries of earthquakes-Illustrations from Chili- Peru- Parallel roads of Coquimbo-West-Inilian archi}1elago- Honduras-East-Inuian archipelago-Reo Sea 118 CHAPTER XI. Newer Pliocene fresh-water formations-Valley of the Elsa-Travertins of Rome-Osseou:; breccias-Sicily-Caves near Palermo-Extinct animals |