The high ground abutting a waterway, lake, arterial, or other agent of transport is called a bank, as in streambank or roadbank. Material may also be stacked, blown, or plowed and said to be banked, as in snowbank. Bank slope varies, from the angle of repose (around 35 degrees) on a loose, established bank to a much steeper incline, as when firm material is scooped out abruptly by a flood. When the cut exceeds 90 degrees, a bank becomes an overhang. Left and right banks are so called with respect to downstream direction. The term also refers to a bank of vegetation growing on a soil slope, as Darwin described in the graceful penultimate paragraph of The Origin of Species: “It is interesting to contemplate a tangled bank . . . and to reflect that these elaborately constructed forms . . . have all been produced by laws acting around us.” Bank also refers to a submerged plateau shelf, or shoal, relatively shallow but navigable, such as the once famously productive Grand Banks off Newfoundland.

Robert Michael Pyle