Theory 27/River deltas/Ratio lens
Delta Shape Is a Force Ratio
The claim
Delta shape is set by the ratio of fluvial to marine energy, so the same sediment load builds a birdfoot, a fan or a cusp depending on wave and tide strength.
01Mechanism
River deposits sediment where it decelerates while waves and tides redistribute it; the ratio determines which process organises the shoreline.
02Prediction
Morphology should track the ratio.
03Refutation
Morphology tracking sediment load would remove marine energy.