498 
Shale, 81, 94, 97, 454, 456. 
Shaly sandstone, 80. 
Shallow water origin of sedimentary 
rocks, 267. 
Shasta, 334, 338, 339. 
Chastina, 338, 339. 
Sheets of intruded lava, 348. 
Shells, as fossils, 390. 
Shore lines, elevated, 297. 
Siderite, 44, 47. 
Sierra Nevada, 308; formation of, 466. 
Silica, 27, 37, 275, 277, 362, 369; as a 
cement, 275; deposit of, 363, 382. 
Silicates, 27, 30; of alumina, 28, 40. 
Siliceous deposits, 97. 
Siliceous rocks, 90. 
Siliceous sandstone, 80. 
Siliceous sinter, 84, 97, 363. 
Silicified wood, 382. 
Silicon, 24, 27, 28. 
Silurian, 398, 400, 402; geography of, 
453 ; life of, 410. 
Sink-holes, 141. 
Slaggy lava, 68. 
Slate, 100, 105, 367, 374, 404. 
Slaty cleavage, 100, 367, 373, 374. 
Smith, William, work of, 388, 396. 
Snake River valley, lava of, 338. 
Snow field, 196, 197, 199, 204, 218. 
Snow line, 200. 
Sodium, 30. 
Soil rock, 75. 
Soils, 75, 120; creeping of, downhill, 144, 
152; glacial, 484; protection offered 
by, 122. 
Solidification of rocks, 53. 
Solution of minerals, 118, 128, 140, 150, 
273; by river water, 156,173; by ocean 
water, 220, 239. 
Solvent power of water, 82. 
Sphagnum, aid in filling lakes, 191. 
Spherulites, 67, 68. 
Spits in lakes, 238. 
Springs, 145, 150. 
Squid, 411, 427. 
St. Anthony Falls, 170. 
Stage, geological, 400. 
Stalactites, 84, 85, 97, 142, 142, 150. 
Stalagmites, 97, 142, 143, 150. 
Starfish, Devonian, 415. 
ELEMENTARY GEOLOGY 
Steam in lava, 67; in volcanoes, 56, 332, 
336, 342, 351. 
Step faults, 292. 
Strata, 73, 260; classification of, 402; 
deposited horizontally, 265; division 
of, 397; position of, 265; sedimentary, 
406 
Stratification, 74; in blown sand, 134; 
cause of, 261; nature of, 260. 
Stratified deposits from glaciers, 211. 
Stratified rocks, 71; changes in, 273. 
Stratigraphic geology, 8, 385. 
Striz, glacial, 208, 209, 485. 
Strike, 284. 
Stromboli, 339. 
Structural geology, 8, 11. 
Subcarboniferous, 402. 
Submerged trees, 298, 300. 
Subterranean rivers, 141, 150. 
Sulphates, 32. 
Sulphides, 32. 
Sulphur, 24, 30, 32. 
Superposition, order of, 297, 396. 
Surf, 224. 
Swamps, 190, 194; of Carboniferous, 
420, 460; mangrove, 250; preservation 
of fossils in, 389. 
Syenite, 66. 
Symmetrical folds, 285, 287, 311, 313. 
Synclinal mountains, 309, 311. 
Syncline, 285, 287, 288, 304, 309, 311, 313. 
Systems of mountains, 307, 308; of 
strata, 401, 402. 
T 
Taconic ranges, 452. 
Talus, 76, 97, 124, 126, 178. 
Taughannock Falls, 168. 
Temperature within the earth, 21. 
Temple of Jupiter Serapis, 294. 
Terminal moraines, 204, 205, 207, 213, 
215, 218, 219, 481, 482, 483. 
Terraces, 180. 
Tertiary, 397; climate of, 473; geogra- 
phy of, 470: life of, 434. 
Teton Mountains, 306. 
Throw of fault, 290. 
Thrust planes, 291, 292. 
Tidal currents, 232, 239. 
