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| | The Origin and Growth of Ripple-mark. |
 | | In smooth and level sand with a single ridge in it, the first swing of the water causes a vortex to form in the lee of this ridge, the brush of which sweeps together a line of sand that is the nucleus of a new ridge (fig. |
 | | The part of this sand that touches the summit C remains there, and the rest is carried along to the left, to a distance varying between a fraction of an inch and several inches, according to the horizontal velocity of the water and the periodic time of the oscillation. |
 | | It follows, therefore, that in established ripple-mark, more sand must be transferred from the end-side to the middle-side of a ridge in one oscillation than is conveyed back again to the end-side in the next oscillation, and it is for this reason that the ridge, as a whole, travels towards the middle of the vessel. |
| www.physics.ucla.edu /~cwp/articles/ayrton/Ayrton_ripple/ripple.html (8684 words) |
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