Give me a moment to do a little research, I am checking now.
Best kept secret in Missouri.
Can't help you, sorry.
well thanks for trying, and I get called the old" geezer a lot" I don't understand why its a secret from what i hear from the old man that lives near the cave its just a very small entrance. and a lot of crawling. I know where Math Branch is so i'll be back there this winter. If i was a quitter i would still be MIA in N Korea. I do appreciate your trying. and i will accept your answer because it right. Charley.
This kind of geologic feature is usually shown on the maps I have here at the house - or on the maps available on line, not just Google. I guess one has to have the right "local knowledge". No doubt you will find it once you are there on the ground.
And, thanks for your service.