A soft bed seems to be useful for more than sleeping, keeping in mind that the word "bed" is used for more than the furniture utilized for sleeping. It's also used for what rivers flow on, and the nature of a river bed seems to make a big difference in the actions of the river. It's long been known that there are areas of ignorance in our understanding of why some rivers erode the bedrock below their channels rapidly and others slowly. Recent studies are beginning to see what makes part of the difference—it's how soft the bed is. No, not the softness of the bedrock, though that plays a part, but whether a good blanket of sediment is available to protect against bedrock erosion.
Our own Rio Grande seems much too lazy to bother with excavation, as
thick sediments smother the bedrock at the pass. Given enough water from the north to
carry away that sediment, and the river could work with a will to dig a deeper valley,
leaving the floodplain high and dry.
Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.
Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.