What caused this strange marking on this rock?
We have found a very unusual stone. Here's what I can tell you about it. It was found on an old farmstead in Montana in what is known to be an old riverbed. There are many other stones that look just like this one, but this is the only one that has the marking. The square shape appears to be solid stone, so I don't think that the stone had a rusted piece of metal laying on it or something to discolor the surface. Does anyone have any idea what may have caused this? If you have any geologist/archaeologist friends please have them take a look at the pictures. I'm just not sure if this was man made/caused or something natural. Thanks.
Close up.
Overall view.
Side view.
Randy Pepprock
Downtown Deco