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Aabout a mile northwest of Fountain, MN (a town that bills it
self as the Sinkhole Capital of the United States) on township road 274
is Fountain Big Spring. It is the spring outlet for the sinkhole on the
previous page. It gave the city of Fountain its name. The spring used
to be the city water supply. Water entering the sinkhole takes 10 to 24
hours to reappar here at the surface.1 We know because
the DNR put about a pound of dye along with 1000 gallons of water down
the sinkhole and found the waer with the dye at this spring about 12
hours later. This is the headwaters of Rice Creek, a state designated trout stream and part of the Root River system. Trout need the cold water (a constant 48o F all year) from the springs to live and reproduce. They will not survive in most of the streams in Minnesota. |
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The water looks cloudy. This
is because of the sediment (soil, mud) that is suspended in the water.
The water is cold because of the cold temperature of the rocks
below the surface, but yesterday some of it was rain water that went
into the sinkhole and other fissures in the carbonate (limestone) rock.
The water is coming out of the Galena Limestone Formation. When the
water hits a rather impermiable layer of shale of the Cummingsville
Formation it flows by gravity to the nearest surface, here at the side
of this hill. These two photos are closer views of the same spring opening. The opening forms a cave where smaller people can squeeze past a narrow obstruction and "go back" about 50 to 100 feet into the hillside. Caves like this can be very dangerous with total darkness, many branches and narrow passages it is easy to get lost. |
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The photo left shows the limestone layers just to the north
of the spring (down the hill). Almost invisible in this rock ledge is
an "overflow" for the Big Spring. When the flow of the water is too
great to make it out of the spring opening water will begin to flow out
of this opening. In the photo at left the creek from the spring head follows the road. In the photo at right a DNR water specialist (I believe his name is Jeff Green) who has done work with the spring and sinkhole stands at the outlet of the underground river. In the spring during high water runoff times the water level will get as high as the rock shelf behind his head. |
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This spring across the road from Big Spring is not connected.
Dye put in the sinkhole that comes out of Big Spring does not come out
of this one. There are a few other springs along the same road that
don't seem to be connected when tested with dye tracing. |
1. Jeff Green, MN DNR
