INDEX 



399 



Swamp deposits, analyses of, 304 



meehanical analyses of, 328 

 seaeoast, analyses of, 327 



formation of, 342 

 reclamation of, 327 

 Syenite, Arkansas, analyses of, 196 



weathering of, 196 

 Syenites, the, 69 



chemieal composition, 69, 70 

 classification of, 69 

 colors of, 69 

 mode of occurrence, 70 

 mineral composition, 69 

 nomenclature of, 69 

 -trachyte group, 68 

 structure of, 69 



Table mountains due to weathering, 



2o9 

 Tachylite, 87 

 Talc, 108 

 Talus, defined, 50 



Temperature changes, effect of in 

 Arabia Petrea, 161 

 in Lower California, 161 

 in Massachusetts^ 160 

 effect on rocks, 158 

 effect of, in Texas, 161 

 Tephrites and basanites, 88 



chemical composition of, 89 

 classification of, 89 

 colors of, 89 



mineral composition of, 88 

 nomenclature of, 89 

 structure of, 89 

 Terminal moraines, 343 

 Terra rossa, 375 

 Teschenite, 84 



Theralite-basanite group, 88 

 Theralites, the, chemical composition 

 of, colors of, mineral composition 

 of, structure of, 88 

 Thin sections of rocks, how prepared, 



38 

 Till, see ground moraine, 340 

 Toadstone, 66 

 Tonalite, 78 

 Trachytes, the, 72 



chemical composition of, 72 

 classification of, 73 

 colors of, 73 



mineral composition of, 72 

 nomenclature of, 73 

 structure of, 72 

 Transportation of rock debris, 274 

 by gravity, 274 

 water and ice, 275 

 wind, 280 



Trap rocks, 85 

 Trass, 122 

 Travertine, 105 



Trees, uprooting, effect of, 384 

 Trowiesworthite, 64 

 , Tuffs, 122, 133 



Yalley drift, see glacial deposits, 

 344 



formed through weathering, 240 

 Variolite, 84 

 Veins, defined, 49 

 Verdantique, 108 

 Vitrophyr, 66 

 Vogesite defined, 70 

 Volcanic ashes, 122 

 dust, 336 



chemical composition of, 



134 

 drifting of, 286 

 f ragmental rocks, tuffs, 122 

 necks, 46 



Wacke, 300 



Wad, 101 



Water, amount in soils, 370 



and ice, mechanical action of, 

 175 

 transporting action, 275 

 capacity of soils, 368 

 chemical activity augmented, 



183 

 effect on dry soil, 369 

 expansive force of, 177 

 relative solvent power of salt 



and fresh, 173 

 protective action of, 239 

 relative run off, 368 

 solvent action of, 168 

 transporting power of, 276 

 Waves, action of, 176 

 Weathering, amount of material lost, 

 220, 273 

 as affected by forests, 266 

 changes in color caused by, 243, 



244 

 difference in kind in warm and 



cold climates, 269, 270 

 effacement of characteristics by, 



249 

 final product of, 362 

 formation of cavities by, 242 

 forms assumed, 238 

 incidental discoloration, 242 



surface contours, 246 

 influenced by humidity, 257 

 by composition, 256 

 by mineral composition, 234 



