I've been told these are pretty rare. When an asteroid hits the earth where there is limestone, these cones result from the shock wave. I dug these in TN at a place called Wells Creek Crater, one of the few places in the world you can find them. The impact site is several miles across, now dissected by the TN River. In the center of the site is a large mound or hill that was pushed up by the impact. That's where the cones are found. This site was recently purchased by the local coal burning power plant as a place to dump their fly ash. The hill with the cones will be covered forever. Gary
