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Scientists have observed the formation of waterfalls by a simple descent of water in a new laboratory study, which could complicate our understanding of the Earth's history.
The waterfalls are beautiful and impressive, but they also open a window to the past, signaling changes in sea level, tectonic activity or climate change. But if the cascades can be formed without external force, as was the case during this new experiment, scientists may have to rethink the conclusions they made about the Earth using stunts.
"There is this idea that we can examine the topography of a planetary body and use it as a record of its history," said author of the study, Joel Scheingross, Assistant Professor, Department of Geological Sciences and Engineering, University of Nevada, Reno. Gizmodo. But if waterfalls can form on their own, "then it means that the notions of using topography and the presence of waterfalls to understand the Earth's history are much more complicated than we thought so.
Earth scientists occasionally use current topography to signal the presence of some changes in the Earth's past. some of the deep valleys of the Yosemite Valley signal glaciers from its past, for example. A combination of various past influences can form a waterfall, including faults crossing rivers over time, landslides or glaciers altering landforms, and climate change affecting the rate of harvest. rivers in the Earth. But the new study adds something to the mix – that stunts might just … pop up.
Researchers modeled a river bed in the laboratory using a piece of polyurethane foam 24 feet long and 1 foot wide to simulate bedrock. They leaned it to a tilt of about 10 degrees and poured water filled with gravel. The gravel was supposed to represent sediments transported by a river.
The water started digging a channel through the foam after just a few minutes and, after two and a half hours, a staircase of pools followed by steep slides, followed by pools again, began to train. At three o'clock, a small waterfall appeared. As time passed, persistent erosion stopped the behavior of this waterfall and a new waterfall began to form, according to the paper published today in Nature.
Of course, the Earth's bedrock is not made of polyurethane foam – but researchers know how to approximate this behavior to better understand what could happen in the real world, where harder volcanic rocks could flow on softer sedimentary rocks. You simply can not wait for thousands of years as part of your experimental protocol. And while this was a proof of concept model in the lab, other researchers were impressed by the work.
"It's a collection of epic experiences that represent a huge laboratory effort and can get some of the first data [that] can answer some of these questions, "Andrew Twin, an assistant professor of earth sciences at the University of Minnesota, who reviewed the paper, told Gizmodo.
"If we want to understand how the surface of the Earth changes over time, it is important to understand all the processes that can change the Earth's surface," said Nicole Gasparini, Associate Professor in the Department of Earth Sciences and Earth Sciences. Environment of Tulane University. who was not involved in the research, told Gizmodo. "This study gives us a break because it says that some of them could form on their own and have nothing to do with the events of the past."
Gasparini and Scheingross both pointed out that these results did not mean that studies of waterfalls to understand the past were wrong. Instead, it means that there is a training method that has not been taken into account and that scientists will now have to think about. Gasparini thought that the next step was to look for waterfalls that could have formed in nature. Indeed, the document cites several examples of cascades with structures similar to those of the team created by Scheingross in the laboratory, such as Bridalveil Creek in Yosemite Valley, California.
But in the end, it is only one trial. Scheingross hopes to conduct more experiments to understand the magnitude of this effect.
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