Diana Wilson, age 14, of Saanon, B.C. for her question:

What is an oxbow lake?

An oxbow lake is narrow and curved. It may be a half circle or two half circles joined like a flying seagull. It is never far from a river because it is always formed by a river. Actually, it is a piece of winding river, cut off and left to die.

A slow, meandering river loops from side to side like a moving snake. Sometimes the main stream finds a short cut. It finds or digs a new channel from the top of one loop to the top of the next loop. A loop or curve of the old river is no longer needed. The new stream passes it by.

In time the new stream builds up silt along its banks. The loop of the old river is now separated from the new stream by a wall of now soil. It is now a lake, an oxbow lake. For a time, it keeps the water it had from the old river. But, unless it is fed by streams or springs, it soon evaporates.