There are caves all over this area. I'm not at all happy that my son has taken up 'spelunking'.
Have you been in your cave, Dave?
The property we lease is adjacent to the farm we own. We have maybe a dozen sinkholes. There are well over a hundred there. We've marked the ones we've seen on the GPS, but just last week I found one out in the middle of a field where I'd been walking many times. Only about 18" square hole, but deep. Al, I worry about the cows breaking their legs...but so far no problem. I'm so paranoid about it I'm pretty careful.
Burnham, I'm not familiar with the holes on the other property to know if they've gotten bigger, or how old they are. But I have seen new ones crop up on our farm, they tend to grow fairly rapidly that first year, then at least the entrance seems to stay the same for the most part. We fill the smaller ones in with field stone, topping them off every year as they settle.....just to keep them from swallowing a tire or ankle.
Common practice in this area is/was to use the larger sink holes as trash holes....old cars, old fencing, water tanks, glassware, trikes. It is discouraged now, of course. There's one big hole over there full of old weathered cow and horse bones....the ones the coyotes didn't drag away anyway.
Brian, I don't think I'll bring up the dynamite idea with Mike, he might like it.