Posted on 03/08/2008 2:03:28 PM PST by blam
The mystery of mammoth tusks with iron fillings
By By Ned Rozell
March 5, 2008
A giant meteor may have exploded over Alaska thousands of years ago, shooting out metal fragments like buckshot, some of which embedded in the tusks of woolly mammoths and the horns of bison. Simultaneously, a large chunk of the meteor hit Alaska south of Allakaket, sending up a dust cloud that blacked out the sun over the entire state and surrounding areas, killing most of the life in the area.
Embedded iron particles surrounded by carbonized rings in the outer layer of a mammoth tusk from Alaska. Inset photo shows how an object ripped through the tusk. Image courtesy Richard Firestone.
Such is the scenario envisioned by Rick Firestone, a staff scientist at the Lawrence Berkeley National Laboratory in California. Firestone and his colleagues have found mammoth tusks and a bison skull with nickel-rich iron particles in them on one side, suggesting the metal fragments all came from the same direction.
Firestone's theory emerged when his colleague, Alan West of Dewey, Arizona, saw at a Phoenix gem and mineral show a mammoth tusk peppered with tiny bits of metal. Intrigued, West and Firestone looked at tusks owned by the same dealer in Calgary. By passing a magnet over mammoth tusks in Calgary, Firestone and West found seven mammoth tusks collected somewhere near the Yukon River and a bison skull from Siberia that had tiny iron fragments burned into them. The fragments also contained nickel.
"One in 1,000 tusks had this material in it," Firestone said.
Firestone also thinks he may have found the divot left by the ancient meteorite, an impact crater that is now occupied by a round body of water named Sithylemenkat Lake in the upper Kanuti River drainage.
"The creeks coming out of the lake are very rich in nickel," Firestone said, referring to a metal associated with meteorites. "And the shape is consistent with a crater from a meteorite that may have been a half a kilometer in diameter‹a pretty large thing."
A meteorite that big would have torched anything within a 100-mile radius and could have buried the mammoths farther away from the crater, preserving the tusks struck by metal fragments. Firestone said the dust kicked up by the meteor would have eliminated any mammoths that survived the meteor's hit.
"There was probably 10,000 years with no mammoths," he said, adding that other mammoths eventually migrated back into Alaska.
Dale Guthrie, one of Alaska's few experts on mammoths, said he found Firestone's theory interesting, but Alaska scientists who know about impact craters think he is probably off on his guess that Sithylemenkat Lake is the place where a giant meteorite struck about 35,000 years ago (the approximate age of the mammoth tusks). Scientists have confirmed only one impact crater in Alaska‹called Avak, near Barrow‹and have discovered only about 140 impact craters on the entire planet.
Buck Sharpton, an expert on impact craters and the Vice Chancellor for Research at the University of Alaska Fairbanks, said the lake would have to be much older than 35,000 years because it has no rim associated with more recent impact craters and doesn't look to him like an impact crater. He thinks the iron bits in the tusks could be cavities filled by "being immersed for millennia in porous sedimentary fill through which iron-rich water percolated."
As for Sithylemenkat Lake, Gordon Herreid didn't mention a possible meteorite impact when he wrote a 1969 geology report on the lake for the state (which ordered the investigation because of possible nickel deposits there). Jan Cannon wrote in the journal Science in 1977 that the lake looked to be the only visible impact crater in Alaska based on a study of Landsat satellite images. One year later, William Patton of the U.S. Geological Survey argued in Science that glaciers, rather than a meteorite, created the lake.
© AlaskaReport News
Bush, Cheney and Haliburton’s fault!
Navigation devices or drunken target practice.
"Be careful there Bob, I'd hate for something to happen. (See my home page)
ah do you mean IED? They aren't necessarily interchangeable.
I am betting on time travelers on some sort of future big game hunt.
Can’t get criticized for killing something that’s already extinct.
My comment was solely directed towards the pronunciation. I have no idea how to pronounce Allakaket. My best guess would be al-LAH-ka-ket.
I always use slugs when I hunt woolly mammoth.
I did that because they asked for “A-LAK-a-ket.” I had to have them spell it before I could look for it.
As you were then...carry on.
Ha ha ha ha ha ha ha...
What utter nonsense.
Is that a dyslexic DUI?
Would have been a pretty bad day to get caught under an airburst iron-nickel meteorite that blast shrapnel over an 100 mile area.
Or, if you’re a Southern Gal like I am, you say “Abalama” after you’ve had a few scoops...I’m a proud Southerner and always will be, even though I reside in England...I can’t wait to get home!
Good for you...we miss you.
Bad things happen to good critters. I really wonder how commonplace these types of catastrophes are.
The Mammoth articles are back!
These iron particles imbedded in mammoth tusks were obviously fillings put in by mammoth dentists. Who Gnu?
Pardon Me, Sugar, I meant truly “Southern” And I say that laughing, as last time I was in New Yawk, they asked me where I was from! Do Yankees even know about us?
Or maybe it was some of this guy's early work...
So THEY'RE the scheiss-heads who stepped on a butterfly and caused Jonson to be elected over Goldwater!
Nah.
My New Zealand neighbor was confused when I told him I wasn't a Yank, lol.
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