Rapid
A rapid is a section of a river where the river bed has a relatively steep gradient causing an increase in water velocity and turbulence. A rapid is a hydrological feature between a run (a smoothly flowing part of a stream) and a cascade. A rapid is characterised by the river becoming shallower and having some rocks exposed above the flow surface. As flowing water splashes over and around the rocks, air bubbles become mixed in with it and portions of the surface acquire a white colour, forming what is called "whitewater". Rapids occur where the bed material is highly resistant to the erosive power of the stream in comparison with the bed downstream of the rapids. Very young streams flowing across solid rock may be rapids for much of their length.
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Famous quotes containing the word rapid:
“In a time of confusion and rapid change like the present, when terms are continually turning inside out and the names of things hardly keep their meaning from day to day, it’s not possible to write two honest paragraphs without stopping to take crossbearings on every one of the abstractions that were so well ranged in ornate marble niches in the minds of our fathers.”
—John Dos Passos (1896–1970)
“In clear weather the laziest may look across the Bay as far as Plymouth at a glance, or over the Atlantic as far as human vision reaches, merely raising his eyelids; or if he is too lazy to look after all, he can hardly help hearing the ceaseless dash and roar of the breakers. The restless ocean may at any moment cast up a whale or a wrecked vessel at your feet. All the reporters in the world, the most rapid stenographers, could not report the news it brings.”
—Henry David Thoreau (1817–1862)
“Missionaries, whether of philosophy or religion, rarely make rapid way, unless their preachings fall in with the prepossessions of the multitude of shallow thinkers, or can be made to serve as a stalking-horse for the promotion of the practical aims of the still larger multitude, who do not profess to think much, but are quite certain they want a great deal.”
—Thomas Henry Huxley (1825–95)