Jessica and I went down to look at the Millbrook Marsh outside of State College. It's a rare calciferous fen - a bog formed on top of a limestone formation. These are terribly rare because limestone formations generally act like God's own sponge, and water can't stand very long on top of limestone without disappearing into the water table. Millbrook Marsh happens to sit at almost the lowest point of Nittany Valley, at the confluence of three streams and a number of springs, and you could say that it's the point at which the water table is higher than the ground level.
Millbrook Marsh isn't nearly as big as, say, the Black Moshannon bog, but it's somewhat startling to find a fen of its size so close to State College's urban area. I first became aware of its existence in 1999, when I lived in a group house on Clover Heights, a low rise between Millbrook Marsh and Spring Creek. At the time, the marsh wasn't particularly developed, and there were only a couple of trails which had been woodchipped by a conservancy group. At a couple of points, you could look over the Millbrook or over the confluence of Slab Cabin Run and the Millbrook to see the marsh proper. This is more-or-less what I expected when we went down there to poke around.
I was quite surprised to find that the conservancy group had bought the nearby microfarm, and had put in a vast network of planked walkways throughout the marsh. Someone had been doing a lot of funds-raising, although I'm willing to wager that it had a lot to do with the new hotel built on the edge of the marsh - probably a trade-off of wetlands construction for the hotel in exchange for the funding of the swanky new walkways. Regardless, what you could barely see by peering from a muddy creekside path, is now directly accessible by walkway. It's much larger than I had guessed. There's a lot of standing water, and all sorts of wetlands flora.
We ran into a woman who owns the private property on the west side of the marsh - she was overseeing some work on the spring which rises on her property - and she told us about a blue heron which lives in the marsh, and had eaten all of the fish she had stocked her spring with. Jessica got a lot more out of the flora than I did - I was always a terrible Boy Scout when it came to plant identification, I'm afraid.