Beaver Dam – Cockeysville, Maryland - Atlas Obscura
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Cockeysville, Maryland

Beaver Dam

A swimming hole in the historic industrial quarry that supplied the marble for the Baltimore Washington Monument.  

What was once a clanging, industrial quarry is today submerged beneath the placid waters of Beaver Dam.

Marble mining in this region began in the 19th century and peaked in the 1920s, surging from hammers and chisels to cranes, sawing machines, and a 50-ton boom derrick. The stone from the Cockeysville region, famed for its hardness and polish, got its big break with the construction of the Washington Monument in Baltimore, which was the first major monument in the United States to honor the first president.

The Baltimore monument is most-known for its crowning statue, which features Washington resigning his post as Commander-in-Chief of the Continental Army. It was shaped out of a carved piece of marble, which was excavated as a single 36-ton block at this site. Ishmael, the narrator of Herman Melville’s Moby Dick, admired the result greatly: “Great Washington, too, stands high aloft on his towering main-mast in Baltimore, and like one of Hercules’s pillars, his column marks that point of human grandeur beyond which few mortals will go.”

An extension to the Northern Central Railway was connected to the site in 1866 and fueled the quarry’s most ambitious digs. The stones transported from this site would supply the stone for both the $50,000,000 Fisher Building in Detroit and for the lower portion of the Washington monument in Washington, D.C. (The obelisk on the national mall was subject to a 25-year break in construction, during which it was halted at 152 feet. Completed, it stands at 554 feet.)

Beaver Dam has been been primarily used as a swimming hole since 1934. When the swimming club first opened, swimmers paid a quarter for per visit. Although it costs slightly more today, it remains just as popular, if not more so. The swim club is open in the summer months and features swimming pools and picnic tables in addition to the 40-foot-deep quarry.

Know Before You Go

Beaver Dam is located about an hour north of Baltimore, off of Beaver Dam Road. If swimming, take note to exercise caution and to only swim while a lifeguard is present. Swimming in quarries can be dangerous, due to loose stones. Hours and additional rules can be found on the swimming club's website.