Possible shipwreck artifact to get CT scan for age
Friday, August 23, 2013
TRAVERSE CITY, Mich. (AP) — The hunt for the Griffin, a ship commanded by legendary French explorer La Salle, has taken an unlikely detour from northern Lake Michigan to a small-town hospital, where modern technology may help determine whether a wooden slab is wreckage from the 17th century vessel.
A team led by explorer Steve Libert, who has searched 30 years for the mysterious craft, hauled the roughly 400-pound beam ashore in June. He discovered a 10.5-foot section of it protruding from the lake bed in 2001 during dive near uninhabited Poverty Island, and received permits this summer to dig beneath it. But his crew discovered the beam wasn’t attached to anything.
Disappointed but undaunted, Libert’s next goal is determining the age of the tree that produced the timber and when it was cut down. He thinks the beam could be the bowsprit — a spur or pole that extends from a vessel’s stem — of the Griffin, which disappeared with its six-member crew and a cargo of furs in 1679.
On Saturday, his crew will lug the massive object to the radiology section of Otsego Memorial Hospital in Gaylord for a procedure usually performed on humans: a CT scan, which generates detailed X-rays. It will be the first time the hospital’s machine has been used for anything other than examining patients, radiology director Andy Lanway said. Elsewhere, CT scans have been used to study the interior of archaeological objects and artworks.
In this case, the plan is to produce images of tree rings within the beam, which is smaller in diameter than a telephone pole. It’s a noninvasive way to seek information that otherwise could be obtained only by cutting into it.
“This is a very important step,” Libert said. “If that piece comes out of the CT scan and it’s some 330 years old ... there’s only one ship it could belong to, and that’s the Griffin.” No other ship of European design was sailing on northwestern Lake Michigan at that time, he said.
The images will be sent to Carol Griggs of Cornell University, an expert in dendrochronology, which uses ring patterns to date trees. Griggs, who visited Michigan last month to see the waterlogged timber, said she hopes to help solve the mystery but made no promises.
She’ll try to match the timber’s ring patterns with those in a Cornell archive that includes trees from centuries ago. If the timber has enough rings, Griggs said, she should be able to estimate the year the source tree was felled.
“I’m a little worried about the bowsprit because from what I could see, it doesn’t have that many rings in it,” Griggs said. “I could see rings at the narrowest end, but there just aren’t a whole lot. But that’s why we’re doing the CT scan.”
It may take a year to complete the analysis and write a report, she said.
The hospital in Gaylord, 225 miles northwest of Detroit, is near the timber’s storage spot— a location Libert is keeping secret to prevent theft or vandalism. The beam is submerged in water and preservative chemicals.
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