
INDEX 
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 
UINTA 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 
443 
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, I17 
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 
