Bluff Spring Fen is probably one of the most unique natural areas in the Chicago region. Bluff Spring Fen is a spring whose water is a year-round 50 some degrees so the spring never freezes. It also supports unique plant and animal communities that need the alkaline-rich soil and water to survive. To get to the entrance you have to enter and park in the Bluff City Cemetery and drive to the rear section for parking and access to the preserve. The cemetery closes at different times during the year so pay attention to the signs! (For cemetery buffs, Bluff City is spectacular - rolling hills of mature oak among the headstones and memorials...) Bluff Spring Fen is located on gravel hills that were left behind when the Wisconsin Glacier retreated around 20,000 years ago. Gravel is a soil type, and I've climbed a large hill full of purple cone flowers and realized I was standing on a bed of gravel!! That's pretty cool in my nerdy book!! This preserve is also adjacent to a gravel mine and I'm told the preserve almost became a gravel mine until it was saved and turned into a preserve. There is also a group of FPCC volunteers who have been working here for many years. There are many single track hiking trails here. I don't believe bikes are allowed and this is a good thing - the trails are narrow and go through tall grasses and flowers - not an ideal biking area. Come and see Bluff Spring Fen in person and enjoy this very unique natural Cook County area. read more