Winding river

On flat terrain, rivers and streams invariably tend to inch forward slowly, much like a crawling snake. At each bend, the flowing water preferentially erodes the outer bank—a process that causes the curve to become progressively more pronounced. Once this erosion reaches a critical point, two adjacent bends eventually cut through to one another; the water then takes a shortcut, straightening its course and shortening the overall river system in accordance with the principle of minimum energy. This process leaves behind a dried-up, horseshoe-shaped lake. This phenomenon is a common sight when flying over the Mississippi Great Plains and the Colorado Plateau in the United States.

This is the distinguishing characteristic of flat terrain.

(Image source: Google Maps; location: Colorado River in Utah, north of the Grand Canyon).

在一块平坦的土地上，河流或小溪总是倾向于像蛇爬行一样向前缓慢蠕动。拐弯之处，水流总是选择性地优先冲刷外侧，越冲越弯。冲蚀及至一定程度，两弯贯通，流水截弯取直，水系变短，满足能量最小原理。并由此留下 一个干涸的马蹄形湖。飞越美国密西西比大平原和科罗拉多高原上时，这种现象十分常见。

这是地形平坦的判别标志。

(照片取自Google Maps， 地点： 犹他州南部科罗拉多河谷，大峡谷区北)