Quezi

Heart-shaped meander (photo by Lazy Susan 23 - CC-BY)

The expression meander is used to describe something that winds around without crossing itself, be it it a creek or river, or a repeating decoration in art or architecture, or also the description of such a line in mathematics.

The word dates back to classical Greece, the name then and now for a river in western Anatolia that does just that: winding back and forth in a fairly level estuary. Many other rivers, of course, meander, why the word is most familiar in this context. The Colorado River meanders through Grand Canyon; the Mississippi meanders—less now. In 1820, Congress began to address the problems of river navigation and ordered the Army Corps of Engineers to reconnaissance the Mississippi. The Corps of Engineers have been active ever since, trying to improve navigation and control the river, proudly so, to judge by its websites, and not just the Mississippi.

Why does flowing water meander? Anything that obstructs its course causes the flow to divert. If the banks of the river are loose earth, the water soon starts to carry it away—to erode it—on the outside curve, curving back at the next obstruction, eroding on the other side of the stream. As Grand Canyon shows, this also happens even if the stream flows through soft rock.

Kids love to play with water, trying to build dams and such, and can discover how meanders develop if they are playing in sandy soil.

As the meandering curves in both directions increase in diameter, they form “oxbows,” the curves eroding towards the neighboring curves. Eventually, the curves can meet, or a larger flow of water breaks through the last bit of land that separates them. That leaves the oxbow as a lake or side-arm of the stream, something familiar on most meandering rivers.

In art and architecture, a rectilinear meander is also called the Greek key pattern. A curving line on the same principle is called a wave or running dog pattern.