Once when I was a kid my family and I drove through Wisconsin. Just south of Tomah and next to Camp Douglas, there's a sandstone formation called Castle Rock. Now, there are many rock formations around the country and world called Castle Rock, but this one is conveniently situated right next to the interstate, well-situated for geological tourism at driving speeds.
Further down the road there's another sandstone formation called Bee Bluff, near a natural area called the Mill Bluff Natural Area which has more of these ancient islands.
Since these are so nicely placed by the interstate, I used Google StreetView to show what it looks like from the road, same way I remembered it. And it pretty much looks the same as I remembered it.