Hamilton Valley is in Meremec State Park, so of course there are caves and springs. Probably more that I noticed.
Caution: There are feral hogs in the Hamilton Valley. Or at least there were in early March, 2013. I'm not going back unless I'm with some other people, and I'm going to call the park office first. I regard feral hogs as the most dangerous large animal in the Ozarks. Big ones aren't scared of people. I'd rather run into a bear.
The cave (image above) is gated, like most every cave in the park. But it's still a fun place to check out. The only problem was that, since the Hamilton Valley doesn't seem to get visited much, the cave seems to be a party spot. When I was there, it was pretty dirty (old fireworks, and general party trash). It's odd that "general party trash" often includes wet and muddy articles of clothing. If people went in the cave, I could see that their clothes would get muddy. But anyone who gets the key from the park is going to be someone who will carry out their muddy clothes.
There's one sweet little spring that runs loudly into Hamilton Creek:
The spring forms a pool (artificial, I think, since I saw some evidence of a crude rock dam).
Even when the woods are otherwise bare, springs themselves are always green. I find their color hypnotic:
Further down the valley, there's a spring which seems to just come from nowhere . . . it starts in the middle of an old field, and there it is:
Same hypnotic green, though: