There are two such streams within a couple of miles of my house (and sometimes a third, which appears sporadically to foretell war (it's accurate, too, though admittedly it's not very often Britain isn't joining in war with someone or other)).
Anyway, these chalk streams, which have often been straightened and dredged to tidy them up, are now being returned to their natural meandering ways, with berms (ledges along the sides of a deepish central channel) brash (logs and branches put into the water to provide shelter for wildlife) and riffles.
Ah yes, riffles. They're shallow bits in the stream where the water gets broken into rough ripples.
The same word also gives you the troughs called riffles which are used in the extraction of mercury and gold. They have groves along the bottom for catching the specks of gold and mercury washed from the earth. One of these groves is called a riffle, too.
Then there's the riffle sound that cards make when you shuffle them; and the riffle you perform when you skim your way through the pages of a book.
Running water, gold, mercury, cards, books...
Was there ever a word for so many magical things?
Do let us know if there is.
Word To Use Today: riffle. This word is probably a form of ruffle with a bit of ripple mixed in for good measure. Ruffle comes from the Middle English ruffelen, and ripple from more or less the same root.