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Timbers from dam hold record of past
Wood salvaged from Fredericksburg's 19th-century crib dam may hold clues to pre-Colonial climate.

 The crib dam spanned the Rappahannock River west of the Falmouth Bridge. It funneled water into the city canal.
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Date published: 10/2/2011


Next to a large metal shed behind Tim Kelly's business in Hartwood sit piles of wood, black with age.

The massive rectangular beams don't look like much. But to Henri Grissino-Mayer, a professor at the University of Tennessee-Knoxville, they're a gold mine, or rather a treasure-trove, of information that could unlock secrets of pre-Colonial Virginia's climate.

Grissino-Mayer, 56, is a well-known dendrochronologist, a scientist who studies tree growth rings for clues to historical rainfall, temperature, environmental changes and wildfires.

Grissino-Mayer and two graduate researchers, Grant Harley and Alex Dye, also with the university's department of geography, took samples of the wood earlier this week in southern Stafford County at Kelly's invitation.

Kelly is the owner of the Woodwright Co. and Woodwright Reclamations, which acquired the wood from Fredericksburg's 1855 crib dam on the Rappahannock River. The crib dam, built with old-growth longleaf pine and white oak, was removed after Embrey Dam just upstream from the city was demolished in 2004.

"This is a gold mine. This is unparalleled in any [wood] project I've seen or been involved with," Grissino-Mayer said.

The wood is unusual for several reasons. First, it is a remnant of an old-growth forest, where towering trees stood untouched for hundreds of years.

And, because it was underwater since 1910 when Embrey Dam was built just downstream, much of it was preserved. The beams came from trees 3 to 5 feet in diameter, probably cut and milled near Fredericksburg around 1854. Some of the trees are thought to have been 250 to 300 years old, dating back nearly to Columbus' arrival in the New World.

"This represents a forest that no longer exists, a time capsule. People look at this and say, 'That's some nasty wood.' But to us, it represents our past. We can obtain so much information from this."


He pointed to a shaded spot on a cross section of one pine beam.

"That's a wildfire, and we can date when that fire occurred. We can date the forest by changes in the ring width. This literally provides information that doesn't exist anymore."

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The wood-and-stone crib dam across the Rappahannock River was finished in 1855 by the Fredericksburg Water Power Co. The dam, built of sturdy old-growth longleaf pine and oak, channeled water into the Rappahannock Canal and a power plant downriver.

The crib dam was submerged after construction of the concrete Embrey Dam in 1910, thus preserving the timbers.

--"River Runs Free," published by The Free Lance-Star, 2004