viii 



CONTENTS. 



PART II. 



CHAPTER XII. 



ON THE DIFFERENT AGES OF THE FOUR GREAT CLASSES OF ROCKS. 



Aqueous, plutonic, volcanic, and metamorphic rocks, considered chronologically 

 — Lehman's division into primitive and secondary — Werner's addition of 

 a transition class — Neptunian theory (p. 153.) — Hutton on igneous origin 

 of granite — How the name of primary was still retained for granite — The 

 term " transition," why faulty — The adherence to the old chronological 

 nomenclature retarded the progress of geology — New hypothesis invented 

 to reconcile the igneous origin of granite to the notion of its high antiquity 

 (p. 155.) — Explanation of the chronological nomenclature adopted in this 

 work, so far as regards primary, secondary, and tertiary periods. 



CHAPTER XIII. 



ON THE DIFFERENT AGES OF THE AQUEOUS ROCKS. 



On the three principal tests of relative age — superposition, mineral character, 

 and fossils — Change of mineral character and fossils in the same continuous 

 formation — Proofs that distinct species of animals and plants have lived at 

 successive periods — Test of age by included fragments (p. 162.) — Frequent 

 absence of strata of intervening periods — Principal groups of strata in west- 

 ern Europe — Tertiary strata separable into four groups, the fossil shells of 

 which approach nearer to those now living in proportion as the formation 

 is more modern (p. 164.) — Terms Eocene, Miocene, and Pliocene — Identi- 

 fications of fossil and recent shells by M. Deshayes — Opinions of Dr. Beck 

 (p. 168.) 



CHAPTER XIV. 



RECENT AND TERTIARY FORMATIONS. 



How to distinguish Recent from Tertiary strata — Recent and Newer Pliocene 

 strata near Naples — near Stockholm and Christiania — in South America, on 

 coasts of Chili and Peru — Rocks of Recent period, with human skeleton, in 

 Guadaloupe (p. 171.) — Shells of living species, with extinct mammalia, in 

 loess of the Rhine — Recent and newer Pliocene deposits in England — 

 Older Pliocene strata in England — Crag — Red and Coralline crag — their 

 fossils in part distinct (p. 175.) — their strata unconformable — belong to the 

 same period — London clay (p. 178.) — Its shells and fish imply a tropical 

 climate — Tertiary mammalia — Fossil quadrumana. 



