The lore states that they saw a depression in the ground and decided it must be a buried treasure. The geological evidence strongly suggests that it was due to a sinkhole. The area is known for sinkholes; the ground gave way as someone was plowing a field near the money pit site. Sinkholes exist on the mainland. The area bedrock is similar to that of Florida... what's Florida known for? Sinkholes.
The sinkhole theory explains a lot of what has been found. The soil in the sinkhole will be softer than the surrounding soil, suggesting it had been previously dug. Debris, including field stones and logs, can fall into the sinkhole. In 1949, a sinkhole on the mainland was excavated and they found the same thing: field stones and logs. The highly porous bedrock would also cause the pit to flood as soon as they dug down to a cavern opening (same thing can happen in Florida) and the water level would change with the tide.
All of the "evidence" found in the pit -- the inscription stone, the gold links, the parchment piece, etc -- are all likely plants. Not a single piece of objective evidence has ever come out of the pit. Not even one. And now that the area has literally been dug to death over the course of 200 years, the likelihood of finding items in excavations is quite high but meaningless. All they are doing is excavating the excavations and nothing short of hauling up treasure has any significance whatsoever.
As I've said, the TV show is designed for one thing and one thing only: selling 30 second ads. If they really wanted to get to the truth they would bring in some real geological experts who can determine the situation. Bring back Woods Hole for a thorough, unrestricted analysis. The problem is that the most likely result will be "natural formation." That won't sell 30 second ads so it will never ever happen.
The bottom line is that there has never been anything to suggest buried treasure. Just some kids (or teens, or adults, it's not clear) who saw a depression and said "Look! Buried Treasure!" That's literally what all of this is based on.