INDEX 
Gas cavities in lava, 56. 
Gasteropods, Devonian, 413, 415 ; Eocene, 
437, 439; Mesozoic, 426, 432; Neocene, 
441. 
Geography of the Archean, 447; Cam- 
brian, 449; Carboniferous, 458; Creta- 
ceous, 467 ; Devonian, 457 ; Eocene and 
Neocene, 470; Juratrias, 464; Ordo- 
vician, 451; past, 394; Quaternary, 
474; Silurian, 453. 
Geological time-scale, 402. 
Geology, development of, 1; difficulties 
of studying, 2; {principles of, 1-9; sub- 
divisions of, 8. 
Georgian beds, 402. 
Geyserites, 98, 275. 
Geysers, 84, 275, 362. 
Glacial bowlder clay, 97. 
Glacial deposits, 76. 
Glacial erosion, 241. 
Glacial Period, 195, 216, 402, 473, 475; 
cause of, 475; changes in Great Lakes 
during, 302; date of, 477; depth of ice 
during, 480; effects of, 487; ice extent 
during, 478; proof of, 484. 
Glacial soils, 121. 
Glacial striz, 208, 209, 219, 485. 
Glacial theory, 485. 
Glaciers, 51, 195; cause of, 195, 218; 
characteristics of, 197, 218; continen- 
tal, 195, 213, 218; deposition by, 207, 
215, 219, 487; erosion by, 207, 219; 
Juratrias, 465; kind of, 195, 218; 
movement of, 206, 478; Piedmont, 
216, 218; transportation by, 203, 215, 
219; valley, 195, 196, 218; withdrawal 
of, 486; work of, 207, 479. 
Glassy igneous rocks, 60, 61. 
Globigerina ooze, 90, 97, 257. 
Gneiss, 102, 105, 368, 377, 404. 
Gold, 24; ores of, 379; in the Sierra, 
467. 
Gorges, 165, 166, 173; caused by glacial 
interference, 484. 
Granite, 61, 66, 347, 348, 404; jointing 
in, 279, 282; metamorphism by, 374; 
weathering of, 72, 110, 111. 
‘Graphite, 94, 99, 105; in Archean, 405. 
Gravel beds, 97; consolidation of, 54; 
furnished by glaciers, 211, 219. 
493 
Great Barrier Reef, 247, 253, 254. 
Great Basin, 324, 327. 
Great Lakes, 302, 482. 
Great Salt Lake, 87, 188, 193. 
Greenland glaciers, 200, 206, 213, 214, 215. 
Ground moraine, 205, 210, 218. 
Groundmass of igneous rocks, 65. 
Groups of strata, 401, 402. 
Guano, 92, 97. 
Gulf Stream, 236; influence of, 477. 
Gypsum, 30, 49, 86, 88, 97, 456, 463; de- 
posit in lakes, 193, 194. 
H 
Hade of fault, 290. 
Halite, 50. 
Hamilton, 402. 
Hawaiian Islands, 314; volcanoes of, 
333, 334, 335, 338, 339, 340, 341. 
Heat, aid of, in metamorphism, 374; aid 
in ore formation, 384; aid of, in weath- 
ering, 113, 128; within the earth, 20. 
Helderberg strata, 402, 457. 
Hematite, 48. 
Henry Mountains, 313, 348. 
Hesperornis, 436. 
Hexagonal joints, 279. 
Hills, 304; of circumdenudation, 306, 
307. 
Hillside springs, 146. 
Holocrystalline rocks, 61. 
Hornblende, 46, 66, 373. 
Horseshoe Falls, 166, 169. 
Hot springs, 83, 84, 146, 150, 362. 
Hudson’s Bay, elevation near, 295. 
Humic acids, 82. 
Huronian, 402, 404. 
Hydrocarbons, 31, 418. 
Hydrogen, 24, 31. 
Hydrous minerals, 31. 
I 
Ice, 50; action of, on coast, 233; aid of, 
in rock formation, 74. 
Icebergs, 217, 219, 239. 
Ice cap of Greenland, 213, 214. 
Ice cave, 205, 206. 
Ice-fall, 202. 
