Horseshoe Bend (the "horseshoe curve") is the name of a meander of the Colorado River located 6 km south of the town of Page, Arizona and corresponding to an ancient plateau eroded. 

The bend is a little downstream of Glen Canyon Dam and Lake Powell. 

A viewpoint located on U.S. Route 89 (en) gives a good overview of the meander.

(from : http://fr.wikipedia.org)