CONTENTS. IX 



PAGE 



Transporting power and velocity, 115. How sediment is 

 carried, 116. 

 Corrasion 119 



' '.: Abrasion, 119. Solution, 122. 



CfoNDiTioNS Affecting the Rate of Erosion 123 



The Influence of Declivity 123 



The Influence of Rock 124 



Physical constitution, 124. Chemical composition, 124. 

 Structure, 125. 



The Influence of Climate.^ 127 



Effects of Unequal Hardness 132 



Rapids and falls, 132. Rock terraces, 140. Narrows, 

 141. Other effects on topography, 142. Adjustment of 

 streams to rock structures, 146. 



Influence of Joints and Folds 150 



Joints, 150. Folds, 154. 



Effect of Changes of Level 161 



Rise, 161. Sinking, 170. Differential movement, warp- 

 ing, 171. 



The Aggradational Work of Running Water 177 



Principles involved, 177. 



The Deposits 181 



Types, 181. Alluvial fans and cones, 181. Ill-defined 

 alluvium, 183. Alluvial plains, 184. Flood-plains due to 

 alluviation, 186. Flood-plains due to obstructions, 188. 

 Levees, 188. Flood-plain meanders, cut-and-fill, 190. Scour- 

 and-fill, 194. Materials of the flood-plain, 196. Topography 

 of the flood-plain, 196. Topographic adjustment of tribu- 

 taries, 197. River-lakes, 198. Dehas, 198. Delta lakes, 204. 



Stream Terraces 204 



Due to inequalities of hardness, 204. Normal flood-plain 

 terraces, 205. Flood-plain terraces due to other causes, 208. 

 Discontinuity of terraces, 209. Termini of terraces, 210. 



CHAPTER IV. 



THE WORK OF GROUND (UNDERGROUND) WATER. 



Conditions influencing descent of rain-water, 213. Supply 

 of ground-water not altogether dependent on local rainfall, 

 215. Ground-water surface — water table, 215. Depth to 



