INDEX 



443 



Tufa, calcareous, 65, 96 ; of La Celle, 



98 

 Tuff, volcanic, 53 ; concretions in, 124 

 Tundras, 407 



Tunnels, construction of, 343 

 Turf, 70 

 Turgite, 6 



Twinning of felspars, 10 

 Type-fossils, 103 



UlNTA Mountains, 397 

 Unconformity, 180, 294 

 Underground water, 350, 420 

 Underlie, 237 

 United States (N. America), ores in, 236, 



266 

 Unsymmetrical folds, 137, 398, 400 

 Ural Mountains, ores of, 234, 265 

 Utah (N. America), 265 



Valleys, 413 



Valley-track of rivers, 417 



Vapour-pores in lava, 35 



Vegetable soil, 376 



Vegetation, an index to soils, 285 



Veins (eruptive), 202, 206 



Veinstone or veinstuff, 244 



Vertical sections, 329 



Vesicular lava, 35, 36 



Victoria (Australia), placers of, 234 



Vitreous rocks, 34, 85 



Volcanic agglomerate, 53 



Volcanic ash, 53 



Volcanic basins, 419 



Volcanic bombs, 53 



Volcanic breccia, 53 



Volcanic stage of consolidation, 36 



Volcanic tuff, 53, 94 



Volcanoes, 395 



Vosges Mountains, 402 



Vughs, 246, 247, 256 



Wad, 9, 232 



Walls of lodes, 251 



Water derived from plutonic sources, 



271 

 Waterfalls, 417 



Water-level, underground, 350 

 Water-supply, 347 

 Wave-marks, 117 

 Wealden area, 232, 410 

 Weathering of rocks, 56, 58, 151, 153, 



372 

 Wells, 358 

 Western Islands, Scotland, basalts of, 



211 

 Whet-slate, 76 

 White trap, 194 



Wind, geological action of, 369 

 Witwatersrand gold-field, 261 

 Wolframite, 249 



Xenoliths, 8, 188, 222, 230 



Zeolites, 26 



Zinc-ore, 249, 250, 257, 260, 263 



Zircon, 8 



Zoisite, 24 



Zone of fracture, 271 



