Return to my Geology pages
Go to my home page
© Copyright 1998, Jim Loy
Rivers meander
(twist and turn, as the river in the diagram) when they are traveling on top of
a relatively flat surface. They do this, rather than flow in a straight line,
because a straight line is not the most efficient path for water to flow. The
water is swirling in various directions, mostly because of friction against the
surrounding earth (the shores and the bottom of the river).
This meandering pattern moves downstream. Each loop of the river slowly moves downstream. The dotted image, in the diagram, roughly shows the future path of our river. The forward edge of each curve (A, in the diagram, for example) undercuts the bank. And sediment is deposited on the trailing edge (B) of each curve. The leading edge is deep, and the trailing edge is shallow.
Occasionally, a river may take a shortcut between loops of its path. In the diagram, if A and C touched one another, the river would cut directly from A to C, leaving the loop below this shortcut as an oxbow lake.
If the land rises, the river cuts deeper and no longer meanders, technically. Instead, it exhibits an entrenched meander. In other words, it is fixed into its previously meandering pattern. The Grand Canyon is a dramatic example.