Gabbro, 274 Ganges, 58, 109, 197 Ganoids, 347 Garnet, 281 Gases, volcanic, 244 Gastropods, 324 Gastrula, 311 Geneva, Lake, 71 Geodes, 49 Geological time, divisions of, 295 Geology, definition of, 1, 3 departments of, 4 Georgia, 18, 373 Geysers, 52, 260 Glacial epoch, 142, 416 Glaciers, 113 abrasion by, 133 Alpine, 118 compared with rivers, 137, 142 crevasses of, 123 deposition by, 138 Greenland, 116 lower limit of, 129 melting of, 126 mode of formation, 118 moraines, 124 motion of, 120, 122, 134 piedmont, 131, 141 plucking by, 133 tables, 130 transportation by, 132 troughs, 137 wells, 129 young and mature, 129 Glauconite, 176 Globigerina ooze, 187 Glyptodon, 441 Gneiss, 283 Goats, 413 Gold, 287, 372 Goniatite, 344, 367 Graded slopes, 25 Granite, 9, 274 Graphite, 312 Graptolites, 320, 339 Gravitation, 22 Great Basin, 357, 360, 374, 376 Great Lakes, 198, 436 Great Plains, 82 Great Salt Lake, 107 Greenland, 115, 126, 378 Green Mountains, 309, 316, 420 Green sand, 176 Ground water, 39 Ground water surface, 40 Gryphæa, 379 Gymnosperms, 363, 377 Gypsum, 12, 335, 357, 371 Hade, 217 Hamilton series, 341 Hanging valley, 1389 Hanging wall, 217 Hartz Mountains, 214 Hawaiian volcanoes, 238, 248, 258, 279 Heat and cold, 13 Helderberg series, 341 Hematite, 310 Henry Mountains, 271, 376 High Plains, 100, 398 Hillers Mountain, 271 Himalaya Mountains, 122, 209, 210, 399 Historical geology, 4, 291 Honeycomb corals, 339 Hood, Mount, 260, 262 Hooks, 165 Hornblende, 274 Hornblende schist, 284 Hudson Bay, 90, 170 Hudson River, 197, 417 Hudson series, 327, 329 Humus acids, 10 Humus layer, 19 Huronian systems, 308 Hwang-ho River, 151 Hydrosphere, 22 Hydrozoa, 320 Icebergs, 116, 148 Iceland, 242, 258 Ichthyosaurus, 389 Idaho, 34, 400 Igneous rocks, 9, 249, 250, 251, 273 Illinoian formation, 429 Illinois, 54, 146, 356, 374 India, 28, 102, 147, 235, 357, 402 Indian Territory, 356 Indiana, 48, 104 Indo-Gangetic plain, 101 Indus River, 101, 110 Insects, 333, 364, 380 Interior of earth, 276 Internal geological agencies, 195 Intrusive masses, 270 Intrusive rocks, 273 Intrusive sheets, 268 Inverness earthquake, 236 Iowa, 29, 69, 73, 80, 86, 336, 356, 374, 431, 433, 439, 442 Iowan formation, 429 Iron ores, 13, 53, 279, 310 Islands, coral, 188 wave cut, 159, 161 Japan, 223, 224, 237 Joints, 5, 31, 216 Jordan valley, 279 Jura Mountains, 141, 212 Jurassic period, 369 Kame terraces, 424 Kames, 424 Kansan formation, 429 Kansas, 41, 50, 100, 336, 357, 373, 374, 429 Kaolin, 12 Karst, 47 Katahdin, Mount, 420 Keewatin ice field, 425 Kentucky, 45, 46, 343, 442 Keweenawan system, 308, 310 Kilauea, 239 Kings River Canyon, 403 Krakatoa, 245