Skip to comments.Geologist investigates canyon carved in just three days in Texas flood
Posted on 06/21/2010 7:40:31 PM PDT by SeekAndFind
In the summer of 2002, a week of heavy rains in Central Texas caused Canyon Lake -- the reservoir of the Canyon Dam -- to flood over its spillway and down the Guadalupe River Valley in a planned diversion to save the dam from catastrophic failure. The flood, which continued for six weeks, stripped the valley of mesquite, oak trees, and soil; destroyed a bridge; and plucked meter-wide boulders from the ground. And, in a remarkable demonstration of the power of raging waters, the flood excavated a 2.2-kilometer-long, 7-meter-deep canyon in the bedrock.
MORE HERE :
Canyon Carved in Just Three Days in Texas Flood: Insight Into Ancient Flood Events on Earth and Mars
In the summer of 2002, a week of heavy rains in Central Texas caused Canyon Lake — the reservoir of the Canyon Dam — to flood over its spillway and down the Guadalupe River Valley in a planned diversion to save the dam from catastrophic failure. The flood, which continued for six weeks, stripped the valley of mesquite, oak trees, and soil; destroyed a bridge; and plucked meter-wide boulders from the ground. And, in a remarkable demonstration of the power of raging waters, the flood excavated a 2.2-kilometer-long, 7-meter-deep canyon in the bedrock.
According to a new analysis of the flood and its aftermath — performed by Michael Lamb, assistant professor of geology at the California Institute of Technology (Caltech), and Mark Fonstad of Texas State University — the canyon formed in just three days.
A paper about the research appears in the June 20 advance online edition of the journal Nature Geoscience.
Our traditional view of deep river canyons, such as the Grand Canyon, is that they are carved slowly, as the regular flow and occasionally moderate rushing of rivers erodes rock over periods of millions of years.
Such is not always the case, however. “We know that some big canyons have been cut by large catastrophic flood events during Earth’s history,” Lamb says.
Unfortunately, these catastrophic megafloods — which also may have chiseled out spectacular canyons on Mars — generally leave few telltale signs to distinguish them from slower events. “There are very few modern examples of megafloods,” Lamb says, “and these events are not normally witnessed, so the process by which such erosion happens is not well understood.” Nevertheless, he adds, “the evidence that is left behind, like boulders and streamlined sediment islands, suggests the presence of fast water” — although it reveals nothing about the time frame over which the water flowed.
This is why the Canyon Lake flood is so significant. “Here, we know that all of the erosion occurred during the flood,” Lamb says. “Flood waters flowed for several weeks, but the highest discharge — during which the bulk of the erosion took place — was over a period of just three days.”
Lamb and Fonstad reached this conclusion using aerial photographs of the region taken both before and after the flood, along with field measurements of the topography of the region and measurements of the flood discharge. Then they applied an empirical model of the sediment-carrying capacity of the flood — that is, the amount of soil, rocks, boulders, and other debris carried by the flood to produce the canyon.
The analysis revealed that the rate of the canyon erosion was so rapid that it was limited only by the amount of sediment the floodwaters could carry. This is in contrast to models normally applied to rivers where the erosion is limited by the rate at which the underlying rock breaks and is abraded.
The researchers argue that the rate of erosion was rapid because the flood was able to pop out and cart away massive boulders (a process called “plucking”) — producing several 10- to 12-meter-high waterfalls that propagated upstream toward the dam, along with channels and terraces. The flood was able to pluck these boulders because the bedrock below the soil surface of the valley was already fractured and broken.
The abrasion of rock by sediment-loaded waters — while less significant in terms of the overall formation of the canyon — produced other features, like sculpted walls, plunge pools at the bases of the waterfalls, and teardrop-shaped sediment islands. The sediment islands are particularly significant, Lamb says, because “these are features we see on Earth and on Mars in areas where we think large flow events have occurred. It’s nice that here we’re seeing some of the same features that we’ve interpreted elsewhere as evidence of large flow events.”
The results, Lamb says, offer useful insight into ancient megafloods, both on Earth and on Mars, and the deep canyons they left behind. “We’re trying to build models of erosion rates so we can go to places like Mars and make quantitative reconstructions of how much water was there, how long it lasted, and how quickly it moved,” Lamb says. In addition, he says, “this is one of a few places where models for canyon formation can be tested because we know the flood conditions under which this canyon formed.”
TITLE : Canyons Form Quickly, Recent Gusher Suggests
Some of the most spectacular canyons on Earth and Mars were probably formed in the geologic blink of an eye, suggests a new study that found clues to their formation deep in the heart of Texas.
Lake Canyon Gorge, a 23-feet- (7-meter-) deep canyon in Comal County, Texas, was carved in just three days by a flood in 2002. The flood scoured a swath of greenery, leaving sand-colored bedrock rubble in its wake.
“It was just a little v-shaped ditched before, but all that material was busted out during that event,” said engineer Tom Hornseth of Comal County, Texas.
Data gathered at this gorge will help researchers reconstruct the formation of ancient canyons.
A single catastrophic flood capable of cutting into bedrock is extremely rare, but the Comal flood gave scientists a front-row ticket to an event similar to those from the planet’s distant past.
Researchers climbed into the canyon, measured the rate and volume of the flood and took aerial photographs to document the rapid erosion. Their study is detailed in the June 20 early online edition of the journal Nature Geoscience.
Gorges are typically formed along pre-existing river channels. The Grand Canyon was formed as the Colorado River slowly wore down the bedrock. That probably took millions of years though, said geologist and study co-author Michael Lamb of Caltech in Pasadena, Calif.
Rapid gorge carving is a baffling example of how incising bedrock doesn’t take millions of years. At Lake Canyon Gorge, a single burst of water carried away heavy rocks, a process known to geologists as plucking. These sedimentary rocks were already broken down into pieces weighing a couple of tons, but exactly how this happens is not well understood, Lamb told OurAmazingPlanet.
Rapid megafloods may have formed canyons in the distant past as glacial ice dams released trapped water. Large floods may be responsible for the formation of some Martian canyons as well, the study suggests.
Young Earth/Creation Ping !
My apologies if it is unlawful for me to create a ping
RE: My apologies if it is unlawful for me to create a ping
I am not aware that there is a rule that says you can’t create a ping.
Pings are in fact FOR INTERESTED PEOPLE.
I might add, although I am not a young earther, I have to admit that The Creation Research Society Quarterly, Journal of Creation and other peer-reviewed journals written by creation scientists, with field research and PhDs, have for years been talking about the power of catastrophic processes to produce the Grand Canyon and other large earth features in just days and weeks by breached dams and other megaflooding processes.
To them, this comes as no surprise. They’ve been arguing this for decades.
I have been researching creation theory lately and finding some interesting things like human footprints with dinosaur footprints, dinosaur-looking art on Inca Stones and that Mt St Helen’s explosion caused trees to petrify on the bottom of a lake in the vicinity. I think it’s fascinating and it somewhat makes me wonder if evolution theory is just as bogus as the global warming hoax. But, don’t quote me on that.
It comes as no surprise to me, either. Once I started researching the writings of Henry Morris, John Morris, and Ken Ham, it was if the scales fell from my eyes. I firmly believe in a young earth.
I don't know the geology of this river but it does not shock me that a gorge could be cut through sedimentary strata quite rapidly.
This area was under the sea not that long ago and is covered with sediment.
I'm a firm believer that history is rediscovered/reinterpreted daily and that people lived in this area a lot longer ago than 15,000 or so years.
THanks for posting this.
Here’s some more info on the site.
Why do you believe that it was 15,000 years or more ago?
Secondly, some of the oldest rock in the world exist in this country. I believe there's much left to be discovered.
My Wife who is a bit *sensitive* to natural phenomenon, believes one of the centers of creation exists in the American southwest.
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Very interesting! Thanks, Arrowhead!
Gradualism takes another hit.
Gradualism takes another hit.
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