Long before humans invented indoor plumbing, the Earth has had its own plumbing systems consisting of caves (pipes), sinkholes (drains) and springs (faucets).
With any plumbing system, things don't always go smoothly. In Cape Girardeau, we're familiar with the downtown storm drains that back up when the Mississippi is above flood stage and start to leak water on Water Street.
Nature has similar plumbing problems. Take, for instance, Ball Mill Resurgence in Perry County. Most of the time, Ball Mill is just a sinkhole, draining surface water that falls into it.
During wet weather, however, enough water pressure builds underground to turn the sinkhole into a spring. It surges water, flooding the banks of a creek bed that is usually dry.
The sinkhole/spring is at the bottom of a circular depression, flanked on one side by a tall bluff.
Following a heavy rain, rocks trapped in the bottom of the depression are bounced around by the gushing water, creating a natural rock tumbler. The "mill" action of the water has created a nice collection of smooth, round "ball" rocks. It's an odd sight for Missouri. To see naturally polished rocks, you usually need to go to a Colorado mountain stream.
I've never visited while the Ball Mill is in action, but rumors suggest that the noise from the rock tumbler can be heard for miles around following an exceptionally heavy rain.
Designated as a State Natural Area, Ball Mill is a short hike along a loop trail. The first portion of the trail passes a cultivated field dotted with obvious sinkholes.
At the fork in the trail, take the left branch. The trail meanders around a series of sinkholes that are uphill from the main Ball Mill sinkhole.
One of the sinkholes is choked with fallen trees from a recent storm (Ice Storm 2008, Ice Storm 2009, or Inland Hurricane 2009, it's hard to say which).
The trail then drops to the bottom of the hill, rounds a corner, and crosses the creek below the Ball Mill.
On the way back to the trailhead, the trail re-climbs the hill, following an intermittent stream and series of small waterfalls.
From Cape Girardeau, take I-55 north to the Perryville exit (#129). Turn right and take Highway 51 to the stoplight at US 61. Turn left on US 61, go north 1 mile, and turn right on Route V. Follow Route V until the highway ends at a fork. Take the right fork (County Road 916) and continue 1.5 miles to the Ball Mill Resurgence parking area on the left.