351Perissodactyl,408Perlitic structure,252Permian series,350,357,360,366Petrifaction,296Petroleum,330,343Phenacodus,406Phyllite,283Phyllopod,323Piedmont Belt,87,214,309,374Piedmont plains,99Pikes Peak,18Pithecanthropus erectus,446Placers,287Plains of marine abrasion,172Planation,81Plantigrade,406Platte River,82Playa,103Playa lakes,104Pleistocene epoch,416Plesiosaurus,389,390Pliocene epoch,395Plucking,133Po River,58,197Pocono sandstone,350,404Porosity of rocks,40Porphyritic structure,252Potholes,59Potomac River,58,66,403Predentata,386Pre-Kansan formation,429Primates,414Prince Edward Island,198Proboscidians,410,441,442Pteropods,325Pterosaurs,391Puget Sound,396Pumice,250Pyrite,13QQuarry water,15Quartz,6,9Quartz schist,284Quaternary period,395,416Quebec,28RRain, erosion,23Rain prints,181Recent epoch,416,440,447Reconcentration of ores,289Record, the geological,291Red clay,187Red River of the North,67Red Sea,221Red snow,115Reefs, coral,188Regional intrusions,272Reptiles,367,383Rhinoceros,408Rhizocarp,343Rhode Island,356Rhone glacier,123Rhyolite,249Richmond, Va.,370Rift valleys,221Ripple marks,180Rivers,54bars,65braided channels,94deltas,108deposition,62discharge,55erosion,59estuaries,85flood plains,93floods,54graded,74gradients,82load of,56mature,72,80,97,98meanders,96plains,99profile of,73revived,85run-off,54structure of deposits,102terraces,96transportation,56,64waterfalls,78young,67Roches moutonnées,134,418Rock bench,156Rock salt,12,357,371Rocky Mountains,375,399,437Ruminants,412SSaber-tooth tiger,413Saguenay River,90,201Sahara,15,146,150St. Elias Range,399St. Peter sandstone,150Salamanders,383Salina series,335Salt, common,106,335Salt lakes,106San Francisco Bay,197Sand, beach,163of deserts,149reefs,165,167storms,145Sandstone,6,7,186Sarcoui,258Sauropoda,386Schist,283Schladebach,277Scoria,250,255Scorpions,339,340,363Scotland,170,220,402Sea,155erosion,156deposition,174transportation,162Sea arch,159Sea cave,158Sea cliff,156,157Sea cucumber,363Seals,414Sea stacks,169Sea urchin,332,379Seaweed,176Sedimentary rocks,8,9Selkirk Mountains,218Septa,338Sequoia,378Shale,8,9Sharks,345,405Shasta, Mount,262,400Sheep,413Shenandoah valley,403Shores of elevation,167Shores of depression,169Siderite,63Sierra Nevada Mountains,24,90,99,224,229,272,287,318,357,371,372,396,398,390,402,437Sigillaria,362,367Silica,6,178Silurian period,316,334life of,338Sink hole,46Slate,207,282Slaty cleavage,207Slickensides,217Snake River lavas,400,401Snakes,384,405Soil,19Solfatara,260Solution,11Soufrière,246South America,357South Carolina,233South Dakota,276,374,397Spanish Peaks,271,376Spherulites,252Spiders,363Spitzbergen,378Sponges,320,379Springs,41thermal,50Stalactite,48Stalagmite,48Starfishes,332Staubbach,140Stegosaurus,387Stoss side,134Stratification,5,64,180Striæ, glacial,114,133,418Strike,203Strike fault,225Stromatopora,331,379Stromboli,244Subsidence,85,183,197Sun cracks,180Superior, Lake,257Superposition, law of,293Susquehanna River,403Sutlej River,209Sweden,199Swine,412Switzerland,28,427Syenite,274Synclinal fold,204Syracuse, N.Y.,436Syringopora,339TTabulæ,339Taconic deformation,329Taconic Mountains,376Talc,284Talc schist,284Talus,23Tapir,409Teleost fishes,349,382,405Tennessee,90,373Terminal moraines,126,422,432Terraces,86,96Tertiary period,395Texas,15,69,71,166,336,356,357,371,373,374,378Theromorphs,383Throw,217Thrust faults,217Till,418Till plains,420Toronto,443Trachyte,249,258Travertine,52Trenton series,327Triassic period,369Triceratops,387Trilobites,322,332,339,363,367Tuff,255Turkestan,103Turtles,384UUnconformity,227Undertow,174Utah,107,271,360,371,396,399Utica series,327VV-Valleys,74Valley drift,128Valley trains,425Valleys,66Vermont,309,329,420Vernagt glacier,129Vertebrates,334,349Vesuvius,247,259,402Virginia,48,84,106,370,403,442Volcanic ashes,244,255cones,257necks,267rocks,249Volcanoes,238causes of,278decadent,260submarine,248tertiary,399WWalrus,414Warped valleys,101Warping,198Wasatch Mountains,375Washington,18,91,150,400Waterfalls,59,78Waves,156Weathering,5chemical,10differential,29mechanical,13Wells,41artesian,44West Virginia,79,357,359White Mountains,443Wind,144deposition,147erosion,151pebbles carved by,152transportation,145Wisconsin,15,18,70,71,90,94,422,426Wisconsin formation,429,431Wyoming,50,98,371YYahtse River,131Yellow Sea,151,170Yellowstone canyon,74Yellowstone National Park,50,51,52,260,261,263,269,400Yosemite,403ZZeuglodon,414Zone of cementation,49,180Zone of solution,45Zones of flow and of fracture,207