Bet You Didn’t Know Texas Brine Works in Russia – February 7, 2013 by flyingcuttlefish 3 Strange earth phenomenon: weird round holes in Russia <PHOTOS Share this:Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window)MoreClick to share on Pinterest (Opens in new window)Click to share on Reddit (Opens in new window)Click to share on Tumblr (Opens in new window)Like Loading... Related
The Louisiana Sinkhole Bugle 
I see they are consistent wherever they go.
They look like very ancient volcanic vents to me.
solves that mystery!