A special congratulations to Cyndy Hunting for being our first reader to work out that the August puzzler showed Garden and Hog islands in northern Lake Michigan. After 19 puzzlers, this was the first time the correct answer came in as a comment on our Facebook page. Just a few hours after Cyndy nailed the location on Facebook, CEM posted the correct answer on our Earth Matters blog.
Meantime, Shawn O and Daniel Bailey were putting forward thoughtful theories about the geological processes that shaped the islands rather than simply worrying about the location. As they suggested, a combination of glacial scouring and rising water levels likely formed the distinctive ridges while the Laurentide ice sheet was retreating and forming Lake Michigan. You can read our Image of the Day caption here. And check out this interesting effort to make detailed maps of the lake floor of an area near Hog Island.