A Niagara-Class Waterfall in Days
Europe’s biggest waterfall likely formed catastrophically instead of gradually, a new analysis reveals.
The Detifoss waterfall in Iceland is the terminus of a 28-km canyon that is 100 meters deep in places (see canyon photo on Science Daily and waterfall photo on Science Magazine). The canyon was formed rapidly in “dramatic floods,” Science Magazine says, that may have been thousands of years apart.
The new study was published in PNAS by researchers who studied helium isotopes at various locations in the canyon. The isotope ratios were so similar, they concluded that the dates of the falls, canyon and rim were nearly contemporaneous.
It’s a bit disturbing to hear them say that geologists tend to ignore catastrophic floods because they don’t understand them:
Extreme flood events have the potential to cause catastrophic landscape change in short periods of time (100 to 103 h [one hour to 42 days]). However, their impacts are rarely considered in studies of long-term landscape evolution (>103 y), because the mechanisms of erosion during such floods are poorly constrained.
According to Science Daily, the lead researcher said, “We think of natural environments as being formed over thousands of years, but sometimes they are shaped very suddenly.” Science Magazine says they dated the erosion to three extreme floods at 9,000, 5,000 and 2,000 years ago, each of which lasted only days. Those dates, the BBC News indicates, are estimated from volcanic eruptions assumed to have melted large volumes of ice from glaciers upstream. The floods caused the headwall of the waterfall to retreat 2 km upstream, “retreating at a startling rate of hundreds of metres within days.”
How does flooding act so rapidly? “Powerful floods can swiftly create canyons by plucking out giant blocks and casting them downstream,” Carolyn Gramling writes in Science Magazine. “How important those types of episodic, catastrophic events are in shaping the landscape has been poorly understood, as such an erosive signature can be difficult to trace through millennia.”
Tia Ghose at Live Science apparently doesn’t want to give flood geologists any ideas:
While the findings show that cataclysmic events can radically transform the landscape, most people shouldn’t expect to come home one day to find a massive canyon where their house once stood. This type of dramatic flooding relies on the interaction of a glacier and a volcano, a unique convergence found only in Iceland, Baynes said.
The original paper is not so selective. “The erosive signature of these events is maintained within a dynamic landscape over millennial timescales, emphasizing the importance of episodic extreme events in shaping landscapes,” the authors say about the significance of their research.
Detifoss falls transports about a fifth of Niagara’s 2,400 cubic meters per second, but at the height of its flow, could have discharged 900,000 cubic meters per second, Live Science reports. A Weather Channel video shows the falls close up, saying it is as wide as a football field and 150 feet high.
This shouldn’t be poorly understood. We’ve seen similar reports from Idaho, Alaska and Argentina about the potential for “extreme events… shaping landscapes” in hours or days. All one has to do is scale it upward by a few orders of magnitude to see the plausibility of a global flood depositing miles of sediment, carving massive canyons and moving continents in short order. Uniform deposits and megasequences of continent-wide extent provides smoking-gun evidence that this happened, regardless of what the book of Genesis says. If Venus and Mars can have global catastrophes, why not Earth?
Notice how the authors said the the impacts of catastrophic events are “rarely considered” by geologists because the processes are “poorly constrained.” Actually, since Charlie & Charlie (Lyell & Darwin) set the paradigm for “slow and gradual accumulation of small incremental changes” (largely as a conspiracy to rid geology of Moses), geologists have been blinded to the evidence all around them (remember this example from 2003?). We hope the slow and gradual accumulation of evidence for catastrophism will continue to build up till the dam breaks, sending a torrent of new thinking into the halls of secular science.
Recommended resource: Earth’s Catastrophic Past (2 volumes) by Andrew Snelling (PhD, geology) has numerous examples of continental-scale evidences for rapid catastrophic processes.