Provided by Gary Parker, St. Anthony Falls Hydraulic Laboratory, University of Minnesota.

The first series shows the role of small changes in abundance of clay in debris flow behavior within the confines of a flume. Scale is in meters. The first frame shows the composition of the flow. These, listed from weakest to strongest, are: (10 seconds, 1.8 MB): Note turbidity current that comes out of the top of the debris flow as it pushes through the standing water. Material falling out of the turbid suspension settles on top of, and is moved by, the debris flow. Carefully watch inside the flow to see the flow freezing from the base up, along discrete shear plains. (15 seconds, 2.1 MB): A slight increase to 6% bentonite results in a very rigid plug-like flow, with plastic deformation (roll over) at snout. Note very little secondary turbidity flow, since very little water flushes through the deposit.