Cave-in Pit, as excavated by Dunfield (1966)

The Field Opens Under the Oxen

In spring 1878 Sophia Sellers, daughter of Anthony Graves, who farmed the east end of the island, was plowing with oxen about 350 feet east of the Money Pit when the ground gave way. Crooker records a hole six to eight feet across and fifteen to eighteen feet deep; Sullivan, from what Sellers told Frederick Blair, has one ox in a well-like hole of the same width. The Sellers filled it with boulders and farmed around it. The spot lay on the supposed line of the flood tunnel from Smith's Cove, and miners took it for an air shaft sunk to ventilate a 500-foot tunnel.

Blair's Men Find a Perfect Circle

Frederick Blair, an Amherst man who had been eleven when the oxen fell, made the pit his Oak Island Treasure Company's first job in 1894. Below the boulders the workmen stood in a circular shaft, almost eight feet across in Sullivan's account and six in Finnan's, with clay walls so hard a pick scarcely marked them, while the fill inside came out without picks. They dug to 52 feet, cribbed the shaft, and augered 16 feet more without striking water; the next morning sea water broke in and rose to tide level. Sullivan names the source as the Truro Company's shaft no. 4; Crooker says only an adjacent shaft or tunnel. Bailing had no effect, the cribbing grew unstable, and the pit was abandoned. Fanthorpe records Blair's reasoning that, since the 1878 collapse had not altered the flow into the Money Pit, the pit must sit a little to one side of it.

Dynamite, and Both Pits Boil

In 1897 Blair's crew drilled a row of holes near the shore at Smith's Cove across the supposed flood tunnel, and the middle hole, which had struck salt water at 80 feet, took a charge of more than 160 pounds of dynamite. When it went off the water in both the Money Pit and the Cave-in Pit foamed and boiled, for almost a minute in Sullivan's account, and Fanthorpe records dynamite oil on the surface at both. Crooker notes the puzzle it left: salt water had entered the Cave-in Pit at 52 feet, far shallower than the 80-foot tunnel the dynamite seemed to find.

Dunfield's Crane, 1966

Robert Dunfield, a petroleum geologist from Canoga Park, California, arrived in the autumn of 1965 and treated the problem as open-pit mining, turning his crane on the Cave-in Pit early in 1966. Crooker records that he dug it to 108 feet, scooping out old timbers at 68 and 100 feet, probably from Halifax Company tunnels of the 1860s, before rain and mechanical failure collapsed the sides into a crater about a hundred feet wide. Finnan says he found nothing. Sullivan calls what remained a shapeless hole filled with water. Three years later, as bulldozers backfilled the pit for Dan Blankenship, the Florida contractor who spent the rest of his life on the island, a granite stone carved with a G inside a rectangle came out of the ground at its edge.

Sinkhole, Air Shaft or Furnace

The Lagina years have used the pit more than dug it: swamp water pumped out in 2016 went into it, and in 2019 ground-penetrating radar reported a feature with a top and a bottom at 90 to 100 feet beneath it, aligned from Smith's Cove through the pit to the Money Pit, and a core nearby found four feet of clean sand near 100 feet with fragments of 1897 dynamite. Joy Steele and Gordon Fader, a marine geologist, note that the pit has long been considered a natural sinkhole and that natural causes cannot be discounted without a direct look; a collapsed furnace is their other reading. Fanthorpe argues it was no simple ventilation shaft, since it never connected to the flood tunnel. The record supports a hand-cut circular shaft with hard clay walls, dug before 1878 by hands the men of 1894 did not take for a searcher's, on or near the flood tunnel line and sharing its water. It does not show who dug it, how deep it went, or whether the shaft was built into a natural collapse.

Sources

• William S. Crooker, Oak Island Gold
• Randall Sullivan, The Curse of Oak Island: The Story of the World's Longest Treasure Hunt
• Lionel and Patricia Fanthorpe, The Oak Island Mystery
• Mark Finnan, Oak Island Secrets
• Joy A. Steele and Gordon Fader, Oak Island Mystery Solved, 2nd ed. (2018)
• Les MacPhie, The Money Pit (2008), survey grid plan, as given in the site record
• The Lagina years draw on the show's own record (episode summaries, Seasons 4 and 7)