Fig. 5.

Conceptual velocity and concentration profiles vertically within a submarine gravity flow. a Low depth-averaged sediment concentrations result in a progressive increase in concentration towards the flow base. The shape of this profile is governed by the downward settling of grains and the upward mixing of turbulence. b At higher depth-averaged concentrations the flow stratifies into a hyperconcentrated basal grain flow layer overlain by a more dilute upper layer. Turbulence is suppressed in the basal layer and particles maintained in suspension via grain collisions and hindered settling effects. Our estimates of depth-averaged concentration indicate the 1929 flow probably had a high-concentration profile