A great valley, a geographic rift that extends thousand of miles. That's what we were looking for in today's Geo Quiz.

Great Rift Valley: http://flickr.com/photos/74671419@N00/

And the answer is: The Great Rift Valley.

This valley contains a chain of lakes and marshes. That makes it a perfect route for millions of birds migrating between Asia and Africa.

The World's Quil Lawrence thinks he spotted about 20 thousand of them on recent bird-watching tour in northern Israel.

Listen