viii CONTENTS 



CHAPTER IV 

 LAND WATERS STREAMS 



THE WORK OF RUNNING WATER 110 



EROSIVE WORK OF RUNNING WATER 114 



Beginning of a valley, 115. The permanent stream, 117. Modes 

 of valley development, 119. Limits of growth, 121. The de- 

 velopment of tributaries, 121. The struggle for existence 

 among valleys and streams, 122. Piracy, 123. Cycle of erosion 

 124. General characteristics of topographies developed by river 

 erosion, 133. Special features resulting from special conditions 

 of erosion, 133. Rate of degradation, 138. 



ANALYSIS OF EROSION 140 



Weathering, 140. Transportation, 144. Corrasion, 146. Cor- 

 rosion (solution, etc.), 148. 



CONDITIONS AFFECTING THE RATE OF EROSION 149 



EFFECTS OF UNEQUAL HARDNESS 153 



EFFECT OF CHANGES OF LEVEL 170 



THE AGGRADATIONAL WORK OF RUNNING WATER 177 



Causes of deposition, 177. Location of alluvial deposits and their 



topographic forms, 179. 

 STREAM TERRACES 191 



CHAPTER V 

 GROUND (UNDERGROUND) WATER 



GENERAL FACTS 195 



WORK OF GROUND- WATER 202 



Chemical, 202. Quantitative importance of solution, 203. De- 

 position of mineral matter from solution, 205. Mechanical, 206. 



RESULTS OF THE WORK OF GROUND- WATER 206 



Weathering, 206. Caverns, 206. Limestone sinks, 208. Creep, 

 slumps, and landslides, 209. Summary, 210. 



SPRINGS 211 



Mineral matter in solution, 213. Geysers, 213. 

 ARTESIAN WELLS : 219 



CHAPTER VI 

 THE WORK OF SNOW AND ICE 



NON-GLACIAL ICE 223 



GLACIERS ~ : ' 1 



General phenomena of, 236. Size, 237. Movement, 238. Like- 

 nesses and unlikenesses of glaciers and rivers, 239. Surface 

 moraines, 242. Debris below surface, 245. Temperature, 245. 

 Compression and friction as causes of heat, 248, Summary. 2 !'.. 



