Labrador, 198 Labrador ice field, 426 Laccolith, 271 Lagoon, 165, 167 Lahontan, Lake, 107, 438 Lake Chelan, 141 Lake dwellings, 448 Lake Geneva, 71 Lake Superior region, 284, 308, 310 Lakes, 70, 222, 432 basins, 97, 110, 127, 139, 141, 164, 165, 167, 191, 221, 222, 235, 259, 423, 432, 435 deposits, 104 glacial, 127, 139, 141, 423, 432, 435 Pleistocene, 435 salt, 106 Laminæ, 5 Landslides, 26, 234 Lapilli, 255 Laramie series, 375 Laurentian peneplain, 84, 308, 432 Lava, 238, 241 Lava domes, 243, 400 Lepidodendron, 362, 367 Lichens, 16 Lignite, 271 Limestone, 7, 177, 178, 190 Limonite, 13 Lingulella, 324 Lithosphere, 21 Lizards, 384 Llamas, 412 Loess, 150, 433 Long Island, 373 Louisiana, 336, 396 Lower Silurian period, 327 Luray Cavern, 48 Lycopods, 362 Magnetite, 279, 310 Maine, 169, 420 Malaspina glacier, 181 Maldive Archipelago, 198 Mammals, 393, 406, 440 Mammoth, 442 Mammoth Cave, 46 Mammoth Hot Springs, 52 Man, 414, 443 Mantle of waste, 17 Marble, 284, 329 Marengo Cavern, 48 Marl, 104 Marsupials, 393, 406 Martha's Vineyard, 161, 373, 395 Maryland, 56, 270 Massachusetts, 106, 162, 257, 309, 408, 417, 429 Mastodon, 410, 441, 442 Matterhorn, 34 Maturity of land forms, 80 Mauna Loa, 239 Meanders, 96 Medina series, 335, 403 Megatherium, 441 Mendota, Lake, 71 Mesa, 31, 32, 153 Mesozoic era, 369 Mesozoic peneplain, 376, 403 Metamorphism, 281 Mexico, 373, 375 Mica, 9 Mica schist, 284 Michigan, 104, 356, 443 Michigan, Lake, 149, 198 Mineral veins, 49, 286 Minnesota, 97, 426 Miocene series, 395 Mississippi, 337 Mississippi embayment, 373, 374, 395 Mississippi River, 56, 57, 82, 94, 96, 109 Mississippian series, 350 Missouri, 18, 236 Missouri River, 55, 97 Mobile Bay, 197 Mohawk valley, 436, 437 Molluscous shell deposits, 177 Mollusks, 324 Monadnock,83 Monkeys, 414 Monoclinal fold, 204 Monocotyls, 377, 404 Monotremes, 393, 406 Montana, 71, 309, 313, 373 Montreal, 268, 437 Monuments, 33 Moraines, 124 Mosasaurs, 390 Mountain sheep, 413 Mountains, age of, 229 life history of, 212, 215 origin of, 90, 210, 222 sculpture of, 33, 137 Movements of crust, 195 Muir glacier, 122, 129