CONTENTS. 



PART I. 



CHAPTER I. 



ON THE FOUR GREAT CLASSES OF ROCKS — THE AQUEOUS, VOLCANIC, 

 PLUTONIC, AND METAMORPHIC. 



Geology defined — Successive formation of the earth's crust — Classification of 

 rocks according to their origin and age — Aqueous rocks (p. 15.) — Their 

 stratification and imbedded fossils — Volcanic rockSj with and without cones 

 and craters (p. 18.) — Plutonic rocks, and their relation to the volcanic — 

 Metamorphic rocks, and their probable origin (p. 21.) — The term primitive, 

 why erroneously applied to the crystalline formations (p. 23.) — Division of 

 the work into two parts ; the first descriptive of rocks without reference to 

 their age, the second treating of their chronology. 



CHAPTER n. 



AQUEOUS ROCKS THEIR COMPOSITION AND FORMS OF STRATIFICATION. 



Mineral composition of strata — Arenaceous rocks — Argillaceous — Calcareous 

 — Gypsum — Forms of stratification (p. 28.) — Original horizontality — thin 

 ning out — Diagonal arrangement (p. 31.) — Ripple mark. 



CHAPTER m. 



ARRANGEMENT OF FOSSILS IN STRATA — FRESHWATER AND MARINE. 



Successive deposition indicated by fossils — Limestones formed of corals and 

 shells — Proofs of gradual increase of strata derived from fossils — Serpula 

 attached to spatangus (p. 37.) — Wood bored by teredina — Tripoli and semi- 

 opal formed of infusoria — Chalk derived principally from organic bodies 

 (p. 41.) — Distinction of freshwater from marine formations — Genera of fresh- 

 water and land shells — Rules for recognizing marine testacea — Gyrogonite 

 and chara (p. 48.) — Freshwater fishes — Alternation of marine and fresh- 

 water deposits — Lym-Fiord. 



A * (5) 



