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August 11, 2008

News Article: Roanoke Times

August 11, 2008

By Tom Angleberger

Q: I've heard rumors about catfish at Smith Mountain Lake near the dam (where they feed on debris sucked in by turbines) being as big as people, but I've never seen or heard from anybody who's turned up a fish that big.

-- Richard Riley, Roanoke

A: This question intrigued me because somewhere deep in my memory I think I found the same giant catfish story -- but this one was from Claytor Lake.

Turns out that these monster fish tales are all over. But the fish? Not so much.

"Every large reservoir I've ever worked on has reports of 'catfish as big as a man' that hang out in front of the intakes and eat everything that comes close to them," recalled Scott Smith, a fisheries biologist with the Virginia Department of Game and Inland Fisheries.

Yes, Smith knows the legend well.

"These giant catfish have all been 'verified' by 'scuba divers working on the dam,' " he recited.

But then he goes and throws reality in our faces.

"Chalk this up to a fish version of an urban legend," Smith declared. "There are large catfish in SML and Claytor -- 30-45 pound range or so, and maybe a little larger. None would qualify as 'giant,' and they typically don't 'hang out' in front of the dams."

By the way, the largest catfish on record in Virginia is a 95-pounder pulled out of the James in 2006.

I've seen a picture of it, and it is disturbingly large; if you saw it in the water you might choose to call it "as big as a man," but it's probably closer in size to a fifth-grader.

Q: I read a story recently about the fossil found in the Boxley Blue Ridge Quarry. How deep is that quarry?

-- Peggy Johnson, Daleville

A: This really was a neat story. Quarry workers found a giant stone bubble, 5 feet around. It turned out to be a 500 million-year-old lump originally created by algae. Scientists call it a stromatolite.

The 2-ton bubble came from 250 feet deep, but the quarry itself goes 450 feet down, Boxley geologist Tom Roller told me.

That's pretty deep. If the Wachovia Tower were built on the floor of the quarry, it wouldn't even come close to the top.

Where has all that rock gone?

Roads, bridges and foundations, explained Roller. "It is the major component in asphalt and concrete and is found on most all construction sites."

While I had Roller's ear, there was something else I wanted to ask him. Can you dig a quarry anywhere you want? His answer: no.

"Depending on what area of the world you live in, good aggregate deposits may be hard to locate. For example: in the Roanoke area suitable deposits often have subdivisions on top of them; in central Virginia around Lynchburg there are complex formations and it is hard to find a large, homogenous deposit; in the Tidewater the bedrock is way too deep to make mining practical."

The rock they dig at the Blue Ridge Quarry is called dolomitic limestone. Roller explained that this means it is not pure calcium carbonate limestone, but contains about 25 percent magnesium carbonate as well.

"The rock we mine has to meet stringent test criteria for hardness, soundness and other physical properties."

As for the stromatolite, it went to the Virginia Museum of Natural History in Martinsville.

Note: Tune in next week for our summer edition of Ask the Readers. Maybe you're the one person who's got the information that someone else wants.

If you've got a question, send it in to woym@roanoke.com or leave it on my voice mail at 777-6476 (please be sure to speak clearly and spell your name). I'll need your name, location and phone number or e-mail address.

Look for Tom Angleberger's column on Mondays.

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