From a perch 400 kilometers (250 miles) above the surface of the Earth on the International Space Station, the arcs of dark meander lakes caught an astronaut’s eye. This photograph shows the point where the Arkansas River enters the wide flats of the Mississippi River floodplain. The river actually rises far to the west, in the Sawatch Range in the Rocky Mountains, and is the sixth longest in the United States.
Unconfined by natural valley walls, the Arkansas was once free to move across the floodplain, and most of the land surface shown in the image was part of the river at some time. The meander lakes show the positions of prior river courses at different times in the past. Meanders migrate constantly, a behavior also revealed by the successive positions of levees, which appear as fine lines and represent ancient river banks.
Today the river is controlled to prevent such movement, which can undercut bridge abutments (such as those of the highway on the lower right). Many locks along the river also allow barge traffic to operate as far inland as Tulsa, Oklahoma. (One such lock lies just off the lower right of the image.) The winding roads of North Little Rock, Arkansas, appear on the left of the image, while Highway 40 crosses the scene under a smudge of high cloud.