Starting from the Robertson Kiosk lot on Lodi Springfield Road (map, directions), we’ll walk the balloon-on-string loop on the west side, a distance of about 1.6 miles.  The walk features a screened overlook of the marsh and fine restored prairie and savanna along and atop a limestone bluff marking the edge of a tunnel channel.   7/13 update:  Postponed due to thunderstorm threat.  New date not yet set.