INDEX 



717 



Unconformity, 270-271. 



basal, 405. 

 Undertow, 200. 

 Ungulates, ancestors of, 598. 



climbing, 619. 



Eocene, 592. 

 Unstratified drift, 160, 172-174. 



relation to stratified, 182. 

 Unsymmetrical valleys, 89. 

 Upham, W., 658. 

 Upthrow of fault, 262. 

 Utica stage, 422. 



Valley of Virginia, soil of, 41. 

 Valley trains, 162, 178. 

 Valleys, direction of, 101. 



glacial, 163. 



growth of, 98. 



structural, 100. 



widened by weathering, 41. 



young, 85. 

 Van Hise, C. R., 393. 

 Vaqueros formation, 580, 581. 

 Varanosaurus, 490, 491. 

 Varieties of coal, 501. 

 Veins, 370, 371-372. 

 Velocity and transportation of streams, 



82, 86. 

 Venericardia planticosta, 628. 

 Vermilion River, decolorization of clifFs, 



37- 

 Vertical faults, 264-265. 

 Vertical range of species, 381. 

 Vesuvius, 295, 302-303, 309, 312, 322. 

 Viscosity theory of glacial movement, 189- 



190. 

 Visp, earthquake at, 281. 

 Volcanic activity in Archaeozoic, 391. 



Cambrian, 407. 



Devonian, 455. 



Miocene, 581, 583-584. 



Ordovician, 423. 



Permian, 477. 



Proterozoic, 394. 



Silurian, 444. 



Triassic, 5 10-5 11. 

 Volcanic ash, 297, 321. 



bomb, 297. 



cinders, 297. 



cones, erosion of, 314-316. 

 slope of, 3 1 1-3 14. 



dust, 297. 



Volcanic — (Continued) 



eruptions, periodicity of, 338. 



gases, 295, 338. 



necks, 316, 317. 

 Volcanism, early, 320. 



importance of, 321-322. 



theories of, 334-339. 

 Volcanoes, classification of, 295. 



distribution of, 318-320. 



in Iceland, 311. 



in United States, 317. 



materials erupted by, 295-298. 



new, 294. 



number of, 318. 



types of, 302-311. 

 Volutilithes petrosus, 628. 



Waagenoceras cumminsi, 483. 

 Walchia, 497, 498. 

 Walcott, C. D., 398, 408. 

 Walled lakes, 204, 205. 

 Warping, 112, 257. 

 Wasatch formation, 519. 

 Waterfalls, formed by drift, 187. 

 Water gaps, 116, 117. 

 Water table, 56-58. 

 Water wear in streams, 83. 

 Waucobian, 402. 

 Wave-built terrace, 212. 

 Wave-cut terrace, 212. 

 Wave motion, 198. 

 Waves, 199. 



breaking of, 200. 



deposition by, 218-224, 2 33* 



earthquake, 202. 



erosion by, 202, 213-214, 23 1. 

 Weathering, 27. 



and erosion, 85. 



and ores, 373. 



chemical effects of, 35-38. 



comparison of chemical and mechanical, 

 38. 



differential, 40-42. 



mechanical effects of, 27-34. 



of metamorphic rocks, 350. 



rate of, 27. 



results of, 38-43. 



spheroidal, 39-40. 

 Wedge work of ice, 28. 

 Wells, 57-58. 

 Whales, 597. 

 Wheeler, W. H., 49, 199, 205. 



