My next stop was Birtle Beach, near the border between Manitoba and Saskatchewan.

The plains of Saskatchewan and Alberta are veined dramatically by huge, oversized river valleys, carrying rivers like the
South Saskatchewan, the Qu'Appelle and the Assiniboine. I was fascinated by the big empty valleys when I saw them from the air in
the spring of 2014 and sought them out on my drive west.

The valleys are flat-bottomed and broad (a mile wide in places), with steep sides a few hundred feet high. The rivers flowing through
the valleys are far too small to have cut them, and now meander across the flat valley floors from side to side, if they haven't been dammed.

The original rivers that cut the valleys were full of glacial runoff from the Ice Ages and had a much greater flow. Agricultural use is
making some of these rivers dangerously small today.

The arrow points to Birtle Beach, on the relatively small valley of the Birdtail River (Birtle is a contraction of Birdtail); the much larger
valley of the Assiniboine cuts across the image in the background.

I crossed the valley of the Assiniboine and Qu'Appelle several times between Birtle and Moose Jaw. Each time I was stunned to see actual
hills and trees and landscape relief after miles of flat prairie.