Posted on 04/09/2008 1:26:29 PM PDT by blam
Grand Canyon Gorge Is 9 Times Older Than Thought
Hope Hamashige
for National Geographic News
April 9, 2008
New research on the Grand Canyon challenges the long-held belief that the canyon was carved by the mighty Colorado River about six million years ago.
Parts of the canyon were formed more than 50 million years earlier than previously thought, according to the new study.
The newfound evidence, which will be presented in the May issue of the Geological Society of America Bulletin, shows that part of the canyon known as Upper Granite Gorge formed more than 55 million years ago.
The history of the Grand Canyon is far more complicated than previously believed, according to Rebecca Flowers, a professor at the University of Colorado, Boulder and the paper's lead author.
"What this tells us is that the entire Grand Canyon didn't suddenly just form six million years ago," Flowers said.
Instead, she explained, the giant chasm may have formed as a series of "ancestral" canyons grew and joined together.
"It is becoming increasingly apparent that the history is more complicated and that different segments developed at different times and subsequently became integrated."
Canyon's Deep Debate
Scientists have long argued over how the Grand Canyon, arguably one of the best known and most beautiful landscapes on Earth, was formed. (See photos of the Grand Canyon.)
The most widely held belief was that it was created when geological forces lifted the area and the Colorado River cut down through the resulting plateau.
The canyon's age had been pegged at about six million years based on sediment deposited by the Colorado as it exited the canyon around Lake Mead (see a downloadable map of the Grand Canyon).
The new study used a different technique, a method of dating rocks developed by geologists at the California Institute of Technology called uranium-thorium-helium dating.
By measuring the amounts of uranium and helium contained in samples collected from the Upper Granite Gorge, the researchers could determine the time at which rocks there cooled, indicating when they were unearthed by erosion.
Because temperatures are hotter below Earth's surface, these cooling rates helps scientists determine when rocks were buried deep underground, and when the forces of erosion exposed them to cooler temperatures closer to the surface.
The results showed that the rocks in Upper Granite Gorge were exposed to cooler temperatures near Earth's surface around 55 million years ago.
It also showed that both the rim and the bottom of the gorge had cooled at the same time, suggesting that the gorge formed from previously existing canyons that eventually connected, rather than a plateau.
"If there had not been a canyon, the gorge and rim samples would have been different," noted Brian Wernicke, a geology professor at Caltech.
Karl Karlstrom, a geologist at the University of New Mexico, pointed out that precursor canyons to the Grand Canyon have been proposed before and that the Caltech research supports those theories.
"Every time we get a new tool we learn something new," Karlstrom said.
"This is a strong addition of data that helps to document what has been proposed—that ancestral canyons existed and became linked together."
Other recent research, including a study by geologists at the University of New Mexico published recently in the journal Science, further challenges the idea that the Grand Canyon was created in one fell swoop by the Colorado.
That research found that parts of the canyon were likely formed about 17 million years ago, adding perhaps more credibility to the notion that the parts of the Grand Canyon were created at different times.
More to Learn
Though there is mounting evidence for the existence of precursor canyons around the Grand Canyon, scientists are still a long way from understanding the full history of how the natural landmark was created.
The new research does not call into question, however, that the Colorado River did, on its present course, start spilling sediment into Lake Mead six million years ago.
"That six-million-year figure is solid, and they are not disputing that," said Joel Pederson, a geologist at Utah State University who researches the Grand Canyon.
What is not known is how the precursor canyons were linked together and what the exact course of the Colorado River was before it started unloading sediment around Lake Mead, he said.
"There have been so many hypotheses how the Colorado got pieced together and when," Pederson said.
Learned something new today.
I thought Lake Mead was only about 70 years old.
He’s been very busy digging around finding lost cities, has written a ton of books and has placed ancient Egyptians in the vicinity of the Grand Canyon.
And not to be sarcastic, So What, our Father has all the answers, consider the lilies how they grow: they toil not, they spin not; and yet I say unto you, that Solomon in all his glory was not arrayed like one of these as the lilys of the field have more beauty than can be explained.
I'm sure it pisses off our Father when the humans he created try to use their curiosity and brains to figure things out about the world he made.
Why do we insist on trying to learn new things? Why can't we just be satisfied with the Holy Word?
Repent all you damn scientists!! (Except if you invented the internet. Or microwave ovens.)
Can you imagine that little seven-year-old calling him Daddy? Or the seven-year-old’s mother, for that matter.
This probably won't help David Hatcher Childress, but I heard someone just last night on AM Radio, talking about "Egyptian artifacts", "mummies", and some old miner being blinded by (...?....) when he stumbled upon some lost trove, down in the canyon. It was on Coast to Coast. Was it Childress?
I find it amazing what silly stories geologists can tell themselves. And few of the stories are sillier than the conventional wisdom about the origin of the Grand Canyon. The river didn't just carve the canyon. It carved it in concert with the uplifting of all the rock along the length of the canyon. They say. Or, anyway, they said.
ML/NJ
I’ve been living in Arizona since 1981. I suppose I should go see that old canyon one of these days. I hear it’s grand.
All rejoice in His power and love, we honor Him in praise.
I remember that the first time I visited Arizona thirty five years ago, I saw the GC and Oak Creek Canyon. Because I could physically drive into and through Oak Creek and exit in beautiful Sedona, it was more inspiring.
The Grand Canyon from the rim is awesome, but it is just too immense to digest from a visit to the rim alone.
I have had hopes that before I get too old I can amend that impression by actually back packing into the big ditch and then obtain the full impression. I alway loved “The Man Who Walked Through Time”.
what are you waiting for? 27 years and you haven't seen it yet?
To really see the canyon in all it's glory, you need to hike to the bottom. You wont regret it!
Wha-aelll... some of 'em should at least cut back on the dope
since it just aint natural, and it aint fair either. How's the rest of supposed to know the canyon is 55 million years old? I mean, it's just a bunch of air, aint it? ---------------
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But not in learning, apparently.
I've seen it, it looks older than that. I'd say 80-85 years old.
The canyon itself doesn't look a day older than 14,000,000 years.
Ping
Thats what I call a natural wonder(s) of the world.
Don’t believe it.
The concensus is that it was formed 6 million years ago
99% of scientists believe this, the debate is OVER!
This crackpot denier must be in the pay of “Big Geology”.
Actually, everyone knows the canyon was formed when a Scotsman lost a shilling down a rabbit hole..
50 million years? That’s not 9 times older than previously thought, that’s 7637.0856881014204979379868642126 times older!
Ping :)
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