Found a sink hole, or impact site

[love2velo]

I was walking on the ice age trail in Wisconsin and noticed a sink hole approx 12ft in diameter (perfectly round) and 3 ft deep. No sure if this could possible be a impact site or not. There was a slight raised area surrounding the sink hole and several rocks around the rim. This was in the depths of the forest and could be an old Indian pit, a sink hole or possible impact site. What would I look for o confirm? I read shatter cones but anything else?

I did grab a rock that appears to be granite but has some small remnants of what could be fusion crust. I took a close up pic of on small patch and then same shot after I scraped it off. Also a shot of general outside (weathered) and inside after a quick grind/sanding. It has a density of 2.9-3.0 and there is NO attraction to a magnet,so I assume terrestrial but I would like to go back and look around as the sun was setting and I needed to get out before the mosquitoes carried me off.

 

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[love2velo]

Here is a pic of hole....sorry the lighting was bad and a bit blurry

 

[love2velo]

here are a view larger shots showing the cluster of surface crust remnants that I scraped off a small bit in earlier pics with a sharp nail/brad - rock is overall much darker on outside but I assume that is just weathering but the bits of dark/ almost rusty crust seems a bit strange, but what do I know? I gave the rock a good scrubbing, just hope it's not dirt LOL

 

[scannerguy1968]

Not sure what it is. Thought maybe what is left from an uprooted tree but there is no hump. But would wonder if that is what it is.
The ice age trail wraps down around where I live to the East. Misses my area. I'm in the driftless area. Vernon County

 

[supertraq]

If it was from a tree the dead tree would probably still be there,also it would be common
to the area. Also when a tree blows over and uproots it will most of the time have the side where the tree went down filled in, in other words not perfectly round because the dirt will be washed down from the rootball.

 

[SoCalDesertFox]

You need to get out there with a metal detector. Most stony meteorites do not survive atmospheric burn, so your better bet is to check for metal remnants with a metal detector.

At a density of ~3, I wouldn't count on anything but trace amounts of iron and nickel, if present at all. I think you need to procure more samples, do check the center of that pit with a metal detector!