I Introduction.- The Science of Petrology.- The Earth Zones.- The Barysphere.- Composition of the Earth Shells.- Chemical Composition of the Crust.- Rocks and their Composition.- The Rock-forming Minerals.- The Classification of Rocks.- I The Igneous Rocks.- II Forms and Structures of Igneous Rocks.- Forms of Igneous Rocks.- Lava Flows.- Intrusions and Their Relations to Geological Structure.- Forms in Unfolded Regions.- Sills.- Laccoliths.- Lopoliths.- Dykes.- Ring-dykes and Cone-sheets.- Volcanic Necks.- Forms in Folded Regions.- Phacoliths.- Chonoliths.- Batholiths.- Multiple Intrusions.- Composite Intrusions.- Differentiated Intrusions.- Structures of Igneous Rocks.- Structure and Texture.- Vesicular and Amygdaloidal Structure.- Block Lava and Ropy Lava.- Pillow Structure.- Flow Structure.- Jointing, Sheet, and Platy Structures.- Columnar and Prismatic Structures.- Rift and Grain.- III Composition and Constitution of Magmas.- The Magma.- Composition of Magmas.- The Pyrogenetic Minerals.- The Physico-chemical Constitution of Magmas.- Primary Magmas.- IV The Formation of Igneous Rocks.- Glass and Crystals.- Crystallisation of a Unicomponent Magma.- Grain of Igneous Rocks.- Formation of Glass.- Crystallisation of Binary Magmas.- Eutectics-Mixed Crystals.- Crystallisation of Ternary Magmas.- Crystallisation of some Ternary systems.- The Reaction Relation.- V Textures and Microstructures.- Definition and Description.- Crystallinity.- The Beginnings of Crystallisation. Crystallites and Microlites.- Devitrification.- Granularity.- Shapes of Crystals.- Mutual Relations of Crystals.- Equigranular Textures.- Inequigranular Textures.- Porphyritic Texture.- Poikilitic Texture.- Directive Textures.- Intergrowth Textures.- Reaction Structures.- Xenolithic Structures.- Orbicular Structure.- Spherulitic Structure.- Fracture Forms.- VI Classification of Igneous Rocks.- Bases of Classification.- The Factor of Chemical Composition.- The Factor of Mineral Composition.- The Factor of Geological Occurrence and Texture.- Tabular Classification.- Nomenclature.- Granite, Granodiorite, and Diorite.- Syenite, Nepheline-syenite, and Related Alkaline Rocks.- Gabbro, Anorthosite, and Peridotite.- Dolerite and Lamprophyre.- Rhyolite and Dacite.- Trachyte and Phonolite.- Andesite and Basalt.- VII The Distribution of Igneous Rocks in Space and Time.- Consanguinity.- The Diagrammatic Representation of Igneous Rock Series.- Kindreds of Igneous Rocks.- Petrographic Provinces and Periods.- Igneous Action and Earth Movements.- Time Sequences in Igneous Rocks.- VIII The Origin of Igneous Rocks.- Variations in Igneous Rocks.- Evidences of Differentiation. Variation within a Single Rock Body.- Theories of Differentiation.- Differentiation by Liquid Immiscibility.- Differentiation by Crystallisation.- Gravitational Differentiation.- Filtration Differentiation.- The Role of Volatile Constituents in Differentiation.- Pegmatite and Aplite.- Assimilation and Hybrid Rocks.- Origin of Alkaline Rocks.- II The Secondary Rocks.- IX Introduction.- General.- The Breaking-down of the Rocks.- Decomposition of Rocks.- Disintegration of Rocks.- Transport.- Deposition.- Classification of the Secondary Rocks.- X The Residual Deposits.- Residual Deposits in General.- Terra Rossa.- Clay-with-Flints.- Laterite and Bauxite.- Soils.- XI Sedimentary Rocks: Mineralogical, Textural, and Structural Characters.- Mineral Composition.- Grain Size.- Heavy Minerals in Sands and Sandstones.- Shape and Rounding of Grains.- Cohesion.- Stratification.- Minor Structures and Markings.- XII Sedimentary Rocks. Descriptive.- Classification.- Rudaceous Rocks: Breccias and Conglomerates.- Arenaceous Rocks: Sands and Sandstones.- Silt and Siltstone.- Argillaceous Rocks: Clays and Shales.- XIII Deposits of Chemical Origin.- Chemical Deposits in General.- Concretions.- Secretions.- Colloids.- Siliceous Deposits.- Carbonate Deposits.- Ferruginous Deposits.- Salts.- XIV Deposits of Organic Origin.- Organic Deposits in General.- Organic Rocks of Calcareous Composition: The Limestones.- Phosphatic Deposits of Organic Origin.- Siliceous Deposits of Organic Origin.- Carbonaceous Deposits: Peat and Coal.- III The Metamorphic Rocks.- XV Metamorphism.- General Character of Metamorphism.- Agents of Metamorphism.- Kinds of Metamorphism.- Facies and Grades of Metamorphism.- XVI Metamorphic Minerals, Processes, and Structures.- Influence of Original Composition.- Influence of Heat and Uniform Pressure.- Influence of Directed Pressure.- Textures and Structures in Metamorphic Rocks.- Shapes of Metamorphic Minerals.- Growth and Mutual Relations of Minerals in Metamorphic Rocks.- Structures of Metamorphic Rocks.- Classification and Nomenclature of Metamorphic Rocks.- XVII Cataclastic Metamorphism and Its Products.- Cataclastic Metamorphism in General.- Slates and Slaty Cleavage.- Crush-breccia and Cataclasite.- Flaser Rocks and Mylonite.- XVIII Thermal Metamorphism and Its Products.- Thermal Metamorphism in General.- Thermal Metamorphism of Clay Rocks.- Contact Metamorphism of Clay Rocks.- Pyrometamorphism of Clay Rocks.- Thermal Metamorphism of Limestones.- Thermal Metamorphism of Arenaceous Rocks.- Thermal Metamorphism of Basic Lavas and Tuffs.- XIX Dynamothermal Metamorphism and Its Products.- Dynamothermal Metamorphism in General.- Dynamothermal Metamorphism of Argillaceous Rocks.- Dynamothermal Metamorphism of Quartzo-Felspathic Rocks.- Dynamothermal Metamorphism of Basic Igneous Rocks and Tuffs.- XX Plutonic Metamorphism and Its Products.- Plutonic Metamorphism in General.- Granulite, Leptynite, Leptite.- Pyroxene-gneiss, Pyroxene-granulite, and the Charnockite Series.- Eclogite and Garnet-amphibolite.- XXI Metasomatism and Additive Processes of Metamorphism.- Metasomatism.- Metasomatic Processes.- Pneumatolytic Metamorphism.- Injection Metamorphism and Autometamorphism.- Lit-par-lit Gneiss, Composite Gneiss, Anatexis and Palingenesis.