LIST OF ILLUSTRATIONS 



FIG. PAGE 



Inner Gorge of the Grand Canon of the Colorado . . Frontispiece 

 i. Forms of the Isometric System: Cube, Regular Octahedron, 



Rhombic Dodecahedron 9 



2. Forms of the Tetragonal System : Right Square Prism, Square Octa- 



hedron 9 



3. Forms of the Hexagonal System : Hexagonal Prism, Rhombohe- 



dron, Scalenohedron 10 



4. Forms of the Orthorhombic System : Rhombic Octahedrons . . 10 



5. Forms of the Monoclinic System : Monoclinic Pyramid and Prism . TO 



6. Profiles of Krakatoa, before and after the eruption of 1883 . . 38 



7. Crater Lake, Oregon 39 



8. Crater-floor of Kilauea, showing the lava lake, Hale-mau-mau . 40 



9. Another view of the crater-floor and walls of Kilauea ... 41 



10. Edge of Hale-mau-mau, showing the ropy forms of lava ... 42 



11. Lava flow of Vesuvius 43 



12. Lava-tunnel, and " spatter-cone " formed by escaping steam, Kilauea 44 



13. Lava stalactites and stalagmites, in lava-tunnel, Kilauea . . -45 



14. Stream gorge, island of Hawaii ; displaying modern columnar lava . 48 



15. Obsidian Cliff, Yellowstone Park. Hexagonal jointing ... 49 



16. Pompeii, showing depth of volcanic accumulations .... 52 



17. Mauna Loa, seen from a distance of 40 miles 53 



18. Mt. Shasta, California -54 



19. Vesuvius and Monte Somma , 55 



20. Truncated tuff cone, island of Oahu 56 



21. Falls of the Snake River 57 



22. Excavation, displaying the transition from rock below to soil above 77 



23. Bad lands of South Dakota 79 



24. Bad-land peak, South Dakota 80 



25. Cliffs and talus slope, Delaware Water Gap. Pa 81 



26. Shales " creeping " under the action of frost 82 



27. Weathered and exfoliating granite, Sierra Nevada, California . . 84 



28. Diagram illustrating how surface and underground drainage may be 



in opposite directions .89 



xvii 



