Surging river current erodes the outer bank of each meander, while along the inner bank the current slows, sometimes separating into an eddy, and deposits sediment. This deposition forms a point bar, extending the tongue of land enclosed by each meander, and over time the meanders migrate outward and downstream like transient bends in a hose whipped side to side. A point bar’s topography tends to be scalloped with a series of crescent-shaped ridges of sand or gravel separated by shallow troughs, all mimicking, more or less, the curvature of the migrating meander. These ridges with their attendant depressions are called—no doubt for their scalloped form—scrolls, or meander scrolls. They are tracks left by the living river.