One of the archived Blockhouse Blog entries [
here] has some interesting things to say about that. Doug Crowell interviews engineer John Wonnacott, who says:
"
If there was a natural cavity formed in the bedrock, possibly from salt water eroding the anhydrite bedrock, that could cause the till above the cavity to slump, thus weakening and loosening the till. However if that happened, the shape of the slumped till would be an inverted cone, and the zone of loose till would be quite wide at the ground surface (something like 60 feet in diameter or more). No one has ever seen a wide slumped area near the Money Pit – the original reports always said the depression in the earth was 12 or 13 feet across.".
So it seems to be this guy's opinion that the Money Pit was not a sinkhole. Just something to consider when weighing the possibilities.
--GT