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
Funnel (ship) built to the same silhouette as the old one, in order to retain this distinctive recognition feature. A key part of the deception practiced by ships carrying out commerce raiding during both the First World War and Second World War was to disguise their ship's outline, and this included using false funnels or by changing the height or diameter of the actual funnel(s). A "mack" is a combined stack and mast, as fitted to some classes of 20th century warships. Although they can reduce top-weight, they have not gained universal popularity due to the problem of exhaust smoke fouling of