Scientists have observed waterfalls simply formed through downhill water movement in a new laboratory study, a result that could complicate our understanding of the history of the Earth.
Waterfalls can be beautiful and impressive, but they are also windows in the past, which signal changes in sea level, tectonic activity or climate change. But if the falls can be formed without an external force, as they did in this new experiment, scientists may have to rethink the inferences they made on Earth using waterfalls.
"C & # 39; it is this idea that we can look at the topography of a planetary body planet and use it as a record of its history," he told Gizmodo the author of the study Joel Scheingross, assistant professor in the Department of Geological sciences and engineering of the University of Nevada, Reno. But if the falls can form themselves ", it means that the notions on how we use topography and the presence of waterfalls to understand the history of the Earth are much more complicated than we thought. "
Earth scientists will occasionally use the current topography to signal the presence of some changes in the Earth's past; some of the deep valleys of Yosemite Valley signal glaciers in its past, for example. A combination of various influences from the past can form a waterfall, including faults that cross rivers that move over time, landslides or glaciers that alter the shape of the earth, and climate changes that affect the rate that rivers have cut across the Earth. But the new study adds something to the mix ̵
The researchers modeled a river bed in the laboratory using a piece of expanded polyurethane 24 feet long, one meter wide to simulate the rocky substrate. They tilted it with a slope about 10 degrees and poured water full of gravel into it. The gravel was to represent the sediments carried by a flowing river.
The water began to carve a channel through the foam after a few minutes, and after 2.4 hours, a staircase of puddles, followed by steep slides, followed by puddles again, began to form. At three o'clock a small waterfall appeared. Over time, the continuing erosion has stopped the behavior of the waterfall and a new waterfall has begun to form, according to the document published today in Nature.
Of course, the substrate of the Earth is not made of polyurethane foam, but researchers know how to roughly resize this behavior to better understand what might happen in the real world, where rocks of volcanic rock can flow on softer sedimentary rocks. You can't just wait thousands of years as part of your experimental protocol. And although this was a proof-of-concept model in the laboratory, other researchers were impressed by the work.
"It's an epic set of experiments that represent a huge laboratory reproduction effort and can get some of the early data [that] that can answer some of these questions," Andrew Wickert, assistant professor of earth sciences at The University of Minnesota, Twin Cities, which reviewed the newspaper, told Gizmodo.
"If we want to understand how the surface of the Earth changes over time, it is important to understand all the different processes that can change the surface of La Terra," Nicole Gasparini, associate professor of the Department of Earth and Earth Sciences told Gizmodo. The environment of the Tulane University which was not involved in the research. "This study makes us reflect because it says that some of these could form themselves and have nothing to do with past events."
Gasparini and Scheingross have both noted that these results do not imply that cascade studies to understand the past is wrong. Instead, it means that there is a training method that has not been taken into consideration that scientists will now have to think about. Gasparini thought that the next step would be to find waterfalls that could have formed like this in nature. In fact, the document highlights several examples of waterfalls with structures similar to those of the Scheingross team created in the laboratory, such as Bridalveil Creek in Yosemite Valley, California.
But in the end, this is just a process. Scheingross hopes to perform more experiments to understand how widespread this effect can be.