Plunge pool height of fall, the volume of water, the resistance of the rock below the pool and other factors. The impacting and swirling water, sometimes carrying rocks within it, abrades the riverbed into a basin, which often features rough and irregular sides. Plunge pools can remain long after the waterfall has ceased flow or the stream has been diverted. Several examples of former plunge pools exist at Dry Falls in the Channeled Scablands of eastern Washington. Plunge pools are fluvial features of erosion which occur in the youthful stage of river development, characterized by steeper gradients and faster water flows. Where
Marsh funnel above, the shear rate in the Marsh funnel is about 2000 . The term Marsh cone is also used in the concrete and oil industries. European standard EN445 and American standard C939 for measuring the flow properties of cement grout mixtures specify a funnel similar to the Marsh cone. Some manufacturers supply devices which they call Marsh cones, with removable tubes with size ranges from 5 to 15 mm. These can be used for quality control by selecting a tube which gives a convenient time, say 30 to 60 seconds. Marsh funnel The Marsh funnel is a simple device for