Chapter III: The Work of Running Water

+Rain and River Erosion+ 57
_Subaërial Erosion without Valleys_ 58
_The Development of Valleys_ 63
By the growth of gullies, 63. Limits of growth, 67. The
permanent stream, 70. Other modes of valley development,
73. Structural valleys, 77. The courses of valleys, 77. The
development of tributaries, 78.

+A Cycle of Erosion. Its Stages+ 80

+General Characteristics of Topography Developed by River Erosion+ 92

+Special Features Resulting from Special Conditions of Erosion+ 92
Bad-land topography, 93. Special forms of valleys; canyons,
94.

+The Struggle for Existence Among Valleys and Streams+ 100
Piracy, 103.

+Rate of Degradation+ 105
Material in solution in river water, 107.

+Economic Considerations+ 108

+Analysis of Erosion+ 110
_Weathering._ 110
_Transportation_ 115
Transporting power and velocity, 115. How sediment is
carried, 116.
_Corrasion_ 119
Abrasion, 119. Solution, 122.

+Conditions 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, warping,
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
tributaries, 197. River-lakes, 198. Deltas, 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.