Nantucket, 373 Naples, 201 Narragansett Bay, 197 Natural bridges, 46 Natural gas, 330 Natural levees, 93 Nautilus, 334 Nebraska, 50, 82, 100, 255, 356 Nebular hypothesis, 304 Neolithic man, 443, 448 Nevada, 104, 107, 222, 288, 289, 360, 400 Névé, 120 New Brunswick, 198 New England, 88, 373, 376, 378, 395, 403, 429, 432, 437 Newfoundland, 198 New Jersey, 148, 166, 168, 176, 196, 268, 269, 309, 310, 373, 437 New Madrid earthquake, 236 New Mexico, 31, 371, 399 New York, 60, 90, 309, 327, 329, 335, 336, 360, 421, 422, 423, 424, 432, 448 Niagara Falls, 60, 199 Niagara series, 335 Nile, 93, 109, 197 Normal fault, 217 North Carolina, 106 North Dakota, 67 North Sea, 170 Notochord, 347 Nova Scotia, 198 Nunatak, 116, 132 Ohio, 82, 198, 329, 335, 441 Ohio River, 55, 82 Oil, 330 Olenellus zone, 328 Olivine, 274 Oolitic limestone, 178 Ooze, deep-sea, 131 Ordovician period, 316, 327 life of, 331 Oregon, 222, 262, 400 Oreodon, 412 Ores, 287, 290 Organisms, work of, 16 Oriskany series, 341 Ornithostoma, 392 Orthoceras, 325, 367, 380 Oscillations, 196 a cause of, 273 effect on drainage, 85 Ostracoderms, 344 Ottawa River, 90 Outcrop, 2 Outliers, 31 Outwash plains, 425 Oxidation, 13 Oyster, 379, 380 Pahoehoe lava,241 Palæospondylus, 344 Paleolithic man, 444 Paleozoic era, 315 Palisades of Hudson, 268 Palms, 377 Pamir, 15 Peat, 94, 104 Peccaries, 412 Pelecypods, 324 Pelée, Mt., 246 Peneplain, 83 dissected, 86 Laurentian, 89, 308, 402 Mesozoic, 376, 403 Pennsylvania, 35, 211, 257, 357, 359, 403 Pennsylvanian series, 350, 351 Perissodactyl, 408 Perlitic structure, 252 Permian series, 350, 357, 360, 366 Petrifaction, 296 Petroleum, 330, 343 Phenacodus, 406 Phyllite, 283 Phyllopod, 323 Piedmont Belt, 87, 214, 309, 374 Piedmont plains, 99 Pikes Peak, 18 _Pithecanthropus erectus_, 446 Placers, 287 Plains of marine abrasion, 172 Planation, 81 Plantigrade, 406 Platte River, 82 Playa, 103 Playa lakes, 104 Pleistocene epoch, 416 Plesiosaurus, 389, 390 Pliocene epoch, 395 Plucking, 133 Po River, 58, 197 Pocono sandstone, 350, 404 Porosity of rocks, 40 Porphyritic structure, 252 Potholes, 59 Potomac River, 58, 66, 403 Predentata, 386 Pre-Kansan formation, 429 Primates, 414 Prince Edward Island, 198 Proboscidians, 410, 441, 442 Pteropods, 325 Pterosaurs, 391 Puget Sound, 396 Pumice, 250 Pyrite, 13 Quarry water, 15 Quartz, 6, 9 Quartz schist, 284 Quaternary period, 395, 416 Quebec, 28