Something old, something new... Grand Canyon surprises

Something old, something new... Grand Canyon surprises
New thermochronologic data show that this segment of Grand Canyon (Marble Canyon, near Cape Solitude) was beneath several kilometers of rock strata, and hence was not carved, until the last 6 million years. This evidence falsifies “old canyon” hypotheses that Grand Canyon was carved in its same location and to within a few hundred meters of its modern depths by 50 million years ago. Instead, the paper presents a new “paleocanyon solution” that reconciles all datasets and shows that different segments of the modern Grand Canyon had different histories and became linked together by the Colorado River after 5-6 Ma to become the modern Grand Canyon. Credit: Laura Crossey, UNM

The Grand Canyon as we know it was formed between five and six million years ago, which is youthful in geological terms, but parts of it could be as old as 70 million years, scientists said Sunday.

Experts have debated for nearly 150 years about the age of the canyon, wrangling over how long it took for the grandiose feature to be gouged out by the Colorado River and its tributaries.

Reporting in the journal Nature Geoscience, researchers in the United States said they had dated from the length of the 446-kilometre (277-mile) canyon and used computer simulations of the topography in their new appraisal.

Two middle sections, called the Hurricane segment and the Eastern Grand Canyon segment, were formed between 50 and 70 million and between 15 and 25 million years ago respectively, they believe.

But two other sections are far younger—they were carved out only between five and six million years ago.

Their creation linked up all four segments, forming a single canyon.

Today, the canyon averages about 1,230 metres (4,000 feet) in depth, falling to around 1,850 metres (6,000 feet) at its deepest point and 29 kilometres (18 miles) at its widest.

Something old, something new... Grand Canyon surprises
Thermochronologic data indicate that the segment shown here (eastern Grand Canyon – the area visited by 5 million annual visitors to the GC National Park) was about half carved (to the level of the red cliffs above the hiker) between 25-15 million years ago. However, the inner gorge shown here was carved in the last 6 million years by the powerful Colorado River (note Horn Rapids). Credit: Laura Crossey, UNM

"Although parts of the canyon are old, we concluded that the integration of the Colorado River through older palaeocanyons carved the Grand Canyon, beginning five to six million years ago," said the study, headed by Karl Karlstrom, a geologist at the University of New Mexico at Albuquerque.

The paper reconciles two schools of thought.

One theory saw an "old" Grand Canyon that was formed as long ago as 80 million years, while the other argued for a "young" canyon five million years old.


Explore further

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More information: Paper: dx.doi.org/10.1038/ngeo2065
Journal information: Nature Geoscience

© 2014 AFP

Citation: Something old, something new... Grand Canyon surprises (2014, January 26) retrieved 17 September 2019 from https://phys.org/news/2014-01-grand-canyon.html
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Mar 14, 2014
@verkle, only the tin foil hat wearing kind.

Mar 14, 2014
Some scientists believe that the Canyon is a mere 5000 years old

@Verkle
without links/proof showing a legitimate study that makes this assertion, then one has to ask where it comes from
the only people saying such a claim as above that I found were creationists, and even the COURT system says that there is NO SCIENCE in the creationist movement's claims of "creation science"
These people are making claims based upon known fallacies that violates the laws of physics

Making a claim that is supposedly "scientific", which you have, without evidence or legitimate science, is conjecture
and it has all the same validity as someone else saying: feeding beans & broccoli to elephants destabilizes the jet stream due to nocturnal emissions
only the tin foil hat wearing kind

@Vietvet
YEP!
pretty much!

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