88. Charcoal was found at 195 feet
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While they explored the Money Pit, Marty and Rick found charcoal at a depth of 195 feet. This is something the episode skimmed through, but it could be a clue as it indicates that possible mining operations could have taken place there. It is also possible that humans who were there lit fires to create the chimney effect, but it could also mean more log layers at depth.
