Miami Dredging: Discovery of 18th Century Cannon

The discovery of an early 18th century cannon during work on the Miami Harbor Deepening Project was certainly an exciting moment for crew members of the Great Lakes Dredge and Dock (GLDD) LLC Company. 

Their discovery was made in August while the U.S. Army Corps of Engineers’ contractor was working at the seagrass mitigation site located north of the Julia Tuttle Causeway in Biscayne Bay. Dredged material was used to create the mitigation site and that’s how GLDD transferred the cannon there.

Dredge-work included using a 40 cubic-yard “clamshell” bucket to excavate the sea bottom. The material, along with the cannon, was loaded into barges and transported to the mitigation area. GLDD made the cannon discovery while spreading the material and removing large debris. Soon afterwards, the contractor determined that the cannon originated from one of the harbor’s turning basins; an undisclosed location for now while project construction is ongoing.

Once we knew the cannon’s origin, we temporarily stopped dredging in that area to conduct further cultural exploration,” said project manager Laurel Reichold.

Corps archeologist Grady Caulk led the exploration team and also delivered the cannon to the Florida Bureau of Archaeological Research in Tallahassee where Florida Secretary of State Ken Detzner was on hand to receive it Oct. 31.

We are thrilled for the opportunity to restore this 18th century cannon at the Department of State’s conservation lab,” said Secretary of State Ken Detzner. “This experience will add to our base knowledge of maritime history in the state of Florida, and it can then be shared with the public to educate about the Sunshine State’s storied past.”

Caulk said everyone was a bit excited and had numerous theories about the cannon and what the exploration might uncover.

There was a Spanish mission at the mouth of the old Miami River entrance and ships visited there often. Old dredgers also used cannons as anchors; and, since the cannon was in inoperable condition with a broken muzzle and missing button at the end – it could have been worn out and thrown overboard or possibly used as ballast for awhile,” Caulk said.

Corps employees conducted a magnetometer and side scan sonar resurvey of the turning basin area in October and identified five magnetic targets that might have represented additional shipwreck remains. The Corps then contracted a cultural resource company to conduct a diver identification of the magnetic targets to determine if the cannon was an isolated artifact or part of a shipwreck.

Five days of explorative diving in November didn’t recover any related objects. The dive team found steel cable, fish traps, a modern anchor and other similar debris.

We would have conducted data recovery mitigation if there was evidence of a potential shipwreck,” Caulk said. But, he added with a small smile, all the excitement at the site is over now. He and others look forward to learning more about the cannon.

Last week, Biscayne National Park cultural resource manager Charles Lawson found an interesting tidbit of information in the Daily Miami Metropolis dated Sept. 3, 1919: “Fourteen old Spanish cannons, recovered by Captain {James} Webster in 30 feet of water a few miles north of Careysfort Light, will be used as mooring anchors for tugs, barges and buoys while working on Government Cut.” 

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