Lecture notes on Chapter 14: Mixed-size Sediments, the Bed-surface Size Distribution, Fractional Transport Rates, Gradation Independence Versus Equal Mobility, a Thought Experiment to Demonstrate the Difference Between Gradation Independence and Equal Mobility, a Look at Some Real Data on Fractional Transport Rates, Movement Threshold in Mixed-size Sediments, Deviations from the Condition of Equal Mobility, and more on Sediment-discharge Formulas: Subsurface-based Models Versus Surface-based Models.