ANNALS of the Association of American Geographers

CONTENTS Page Underfit Rivers , 3 Lehmann's Principle 4 Initial Irregularity of River Courses.. 4 Development of Initial Bends into Systematic Curves . . 5 Thompson's Principle 6 Down-stream Migration of Meanders.. Amphitheaters and Spurs ..7 Development of Floodplains .. 8 Changes in Amphitheaters and Spurs.. 9 Widening of a Floodplain..10 Cut-off Meanders ..10 Meanders of Large and Small Rivers.11 Variations in Rockl Resistance..11 Anomalous River Meanders..12 Landslides, Tree-falls and Sod-slips .. 13 Relation of River Volume to Meander Radius 14 Incised Meanders of Revived Rivers.15 Underfit Rivers in Incised Meandering Valleys . . 16 Underfit Rivers and River Floods..16 River Capture'and Underfit Rivers 18 Climatic Change and Underfit Rivers 19 Lehmann's Explanation of Underfit Rivers . . 19 Loss of Surface Flow to Deep Percolation 20 Loss of Surface Flow to Shallow Underflow . . 20 Varying Equilibrium of a Graded' River . . 22 Regain of Surface Flow in Old Age.. 22 Underfit Rivers and Underground Waters . . 23 Terminology of Meandering Valleys and Underfit Rivers. . 23 The Larger Lesson of this Problem. . 25 Application of Lehmann's Principle to Regional Geography . . 27