Where on Earth? - April 2014

Clues for April 2014:

1. The low rolling hills seen in the mid-ground of this photo are ripple marks formed when an ice dam impounding an enormous glacial lake gave way sometime between 15,000 and 12,000 years ago, unleashing a massive flood that scoured the landscape all the way to the Pacific Ocean.

2. The ripples — akin to those you might see in the intertidal zone of a sandy beach, but reaching heights up to 15 meters and partially composed of large detrital boulders — were first identified as having been formed by a flood event by geologist Joseph T. Pardee in the 1940s.

3. The area where the ripple marks are found, which lies about 40 kilometers southwest of one of the biggest lakes in the western U.S., was designated a National Natural Landmark in 1966.


Name the area and state where these ripples are located.

Scroll down for the answer


Answer: The low rolling hills of Camas Prairie — part of Glacial Lake Missoula National Natural Landmark near the Clark Fork in western Montana — reach heights up to about 15 meters. The hills are preserved ripple marks that formed when the massive lake drained sometime between 15,000 and 12,000 years ago. Photo is by Peter Balleau.

April Winners:
John C. Balla (Port Orchard, Wash.)
Mike Burton (Fargo, N.D.)
R.J. Gauthier-Warinner (Interlochen, Mich.)
Paula LaPoint (Chapel Hill, N.C.)
Paul R. Troop (Oakdale, Calif.)

To submit your photographs to our Where on Earth? contest, send them via e-mail to



31 Mar 2014