The Student’s Elements of Geology By SIR CHARLES LYELL, BART., F.R.S. AUTHOR OF “THE PRINCIPLES OF GEOLOGY,” “THE ANTIQUITY OF MAN,” ETC. Thecosmilia annularis WITH MORE THAN 600 ILLUSTRATIONS ON WOOD. NEW YORK HARPER & BROTHERS, PUBLISHERS 1878 Tertiary or Cainozoic, Secondary or Mesozoic, Primary or Paleozoic CONTENTS. PREFACE Chapter I—ON THE DIFFERENT CLASSES OF ROCKS. Geology defined. — Successive Formation of the Earth’s Crust. — Classification of Rocks according to their Origin and Age. — Aqueous Rocks. — Their Stratification and imbedded Fossils. — Volcanic Rocks, with and without Cones and Craters. — Plutonic Rocks, and their Relation to the Volcanic. — Metamorphic Rocks, and their probable Origin. — The term Primitive, why erroneously applied to the Crystalline Formations. — Leading Division of the Work. Chapter II—AQUEOUS ROCKS—THEIR COMPOSITION AND FORMS OF STRATIFICATION. Mineral Composition of Strata. — Siliceous Rocks. — Argillaceous. — Calcareous. — Gypsum. — Forms of Stratification. — Original Horizontality. — Thinning out. — Diagonal Arrangement. — Ripple-mark. Chapter III—ARRANGEMENT OF FOSSILS IN STRATA—FRESH-WATER 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. — Wood bored by Teredina. — Tripoli formed of Infusoria. — Chalk derived principally from Organic Bodies. — Distinction of Fresh-water from Marine Formations. — Genera of Fresh-water and Land Shells. — Rules for recognising Marine Testacea. — Gyrogonite and Chara. — Fresh-water Fishes. — Alternation of Marine and Fresh-water Deposits. — Lym-Fiord. Chapter IV—CONSOLIDATION OF STRATA AND PETRIFACTION OF FOSSILS. Chemical and Mechanical Deposits. — Cementing together of Particles. — Hardening by Exposure to Air. — Concretionary Nodules. — Consolidating Effects of Pressure. — Mineralization of Organic Remains. — Impressions and Casts: how formed. — Fossil Wood. — Goppert’s Experiments. — Precipitation of Stony Matter most rapid where Putrefaction is going on. — Sources of Lime and Silex in Solution.