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Saturday, October 18, 2008

A sign I never saw on a beach in Minnesota

While spending the weekend in the Beaufort area of the South Carolina’s Low Country, I came across this sign (pictured) at Hunting Island State Park. It turns out that the term “groin” (outside the USA know as “groyne”) comes from the Latin word for snout, which aptly describes its geometry – an underwater structure aimed at reducing beach erosion.

The other photo, which I took at high tide facing north, shows this groin's beneficial effect. Hunting Island lost 400 feet at the northern end in only one year in the mid-1800’s – just after a lighthouse was built at that location. Ironically, the Confederates blew it up to prevent the Yankees from taking advantage of the beacon for their invasion of nearby Port Royal. It never would have lasted in any case. In fact, a second lighthouse built in 1874 had to be relocated only 14 years later due to being undercut by the advancing Atlantic Ocean. However, the engineers were smart enough to consider this possibility, so they constructed the tower with curved cast iron panels that were designed to be dismantled and rebuilt. Brilliant!

Standing at mid-island after its move and being further protected by a series of groins, the Hunting Island Lighthouse should stand tall for many more years. See it pictured beautifully at this web page by “America’s premier lighthouse painter” Roger Bansemer . For those of you engineers that may be interested more in how things work (rather than history and aesthetics), see this Wikipedia detailing of groyne hydraulics. Check out the groyne warning sign – it’s a hoot! (To avoid any misunderstandings, I prefer the alternative spelling.)


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