INDEX 



Abrasion, 88. 

 Acidic rock, 24. 

 Agents, geologic, 10. 

 Aggradational processes, 11. 

 Algae, 293. 



Algonkian period, 322. 

 Alluvial fan, 172, 175, 176. 

 Alluvial plain, 176. 

 Alluvial soil, 17. 

 Alluvial terraces, 183. 

 Ammonite, 399, 426. 

 Amoeba, 295. 



Amphibians, 301, 374, 386. 

 Amygdules, 32. 

 Angiosperm leaves, 420. 

 Angiosperms, 294. 

 Animals, 294. 



Ordovician, 346. 

 Animal groups, Ordovician, 343. 

 Animikean system, 323. 

 Anorthosite, 30. 

 Anthracite, 380. 

 Anticlines, 66. 

 Appalachia, 332, 398. 

 Appalachian Mountains, 398. 

 Appalachian trough, 390. 

 Archaean system, 317. 

 Archaeopteryx, 412. 

 Archseozoic era, 317. 

 Arizona, 326. 

 Artesian wells, 112. 

 Arthropods, 299, 356. 

 Atmosphere, 13. 



work of, 86. 

 Atoll, 260. 

 Augite, 21. 



Bacteria, 293. 

 Bad Lands, 436. 

 Bar, 248. 



Barrier island, 248. 

 Barrier reef, 260. 

 Basal unconformity, 33. 

 Basalt, 29. 

 Basalt-porphyry, 29. 

 Base level, 140. 

 Basic rocks, 24. 

 Basin, drainage, 142. 

 Basins, glaciated, 219. 

 Batholiths, 51. 

 Bed, 54. 



Bedding plane, 18, 54. 

 Beds, limestone, 64. 

 Beheaded stream, 169. 

 Belt, cementation, 80. 



weathering, 80. 

 Bergschrund, 200. 

 Birds, 301. 



Cretaceous, 426. 



Jurassic, 412. 

 Bituminous coal, 380. 

 Bivalves, 298. 

 Blastoid, 297, 373. 

 Block mountains, 276. 

 Blowhole, 243. 

 Bombs, 33. 



Brachiopods, 298, 336, 343, 354 

 364, 377, 385, 399. 



progress of, 343. 

 Braided rivers, 178. 

 Breakers, 236. 

 Breccia, 38. 



volcanic, 33. 



Bridge, natural, 118, 244. 

 Bryophytes, 293. 

 Buttes, 167. 

 Bysmalith, 51. 



Calcareous springs, 111. 

 Calcite, 22. 

 467 



