A channel is a confined flow of water on the surface of the Earth defined by its banks. This insistent flow of water can be controlled and artificial (as in the related word canal), or a natural channel, the course of which is largely dependent on the resistance of the material the water makes its way through. Mark twain is an old Mississippi River term; it’s the second mark on a line that measures depth to two fathoms, or twelve feet, a safe depth for a steamboat—helpful in finding the navigable channel hidden in the river. Although a channel through rock is fixed, in the soft sand and clay bed of the Mississippi the changing force of the water flow makes the channel dynamic: it shifts from day to day. Only by study can you learn the signs, the secrets, that will tell you where the channel lies. If you misread the river, the bottom may come off the boat, the cargo might sink, people could die. The river has a whole language, a vocabulary of signs. To read the river is to find the channel. Hence in Life on the Mississippi Mark Twain writes: “Piloting becomes another matter when you apply it to vast streams like the Mississippi and the Missouri, whose alluvial banks cave and change constantly, whose snags are always hunting up new quarters, whose sandbars are never at rest, whose channels are forever dodging and shirking, and whose obstructions must be confronted in all nights and all weathers without the aid of a single light-house or a single buoy.”

Susan Brind Morrow