Chutes and pools began taking shape, and that's where the waterfall magic began.Īs the pools continued to deepen, the rushing waters eventually lingered in some places so much that the suspended gravel fell out of solution. Within a few minutes, a half moon-shaped channel started to cut its way into the foam. With the system flowing, the team waited and watched, pausing the water every so often to evaluate its effects. This grit was a key component to the formation of channels, Scheingross says, since sediments in flowing water act like sandpaper, grinding away layers of underlying rock. The surface was tilted to a nearly 20-percent slope, and then the team flooded it with a stream of water and sediment. ![]() The team set a flat surface of this foam in a flume that stretched 24 feet long and almost a foot across. thesis and actually observe changes in the lab,” says Scheingross, who is now an assistant professor at the University of Nevada Reno. “Instead of having to wait decades or millennia to run these experiments, we can run them on a timescale of a Ph.D. It erodes quickly, but at a rate that's remarkably scalable to different types of rock. So the researchers turned to a Pepto Bismol-pink polyurethane foam-similar to the foam florists use for flower arrangements-to model the system. The process is exceedingly slow in nature, with water shaving down the underlying rocks at just a fraction of the speed at which your fingernails can grow. Scheingross and his colleagues wanted to put this idea to the test. Some even proposed these pools could eventually become the starting point of waterfalls. A river runs through it (in the lab)īy simulating rivers in the laboratory, scientists previously found that the water's motion could form undulating pools along its path. We can’t necessarily attribute these landforms to some external driver or some local driver they can pop up all on their own.” “It raises up a hand and says, Wait a minute, everybody. “That to me is the golden internal message,” says Ben Crosby, a geomorphologist at Idaho State University who was not involved in the study. ![]() But he says it does call for a rethink of how scientists interpret the factors that sculpt landscapes. He cautions that the work is still preliminary and is limited to lab-based simulations. “This new formation mechanism really complicates our understanding of being able to use topography and the presence of waterfalls to solve for past changes in Earth history,” says study author Joel Scheingross, who completed this research as a doctoral student at the California Institute of Technology. Instead, the researchers suggest that a river's turbulence alone is enough to carve steep pitches in a uniform bed of rock, spontaneously forming a waterfall. However, the new work concludes that a dramatic change in the rock or external force isn't always necessary to create these dizzying cascades. ![]() Others could be glacially slow, like sea-level changes or even different types of rock eroding away at different speeds. Some waterfall-forming processes could be fast, like an earthquake shifting blocks of land to create a step over which water can fall. Until now, scientists largely reckoned that waterfall formation needed some type of external trigger acting on a river. Find out the origins of our home planet and some of the key ingredients that help make this blue speck in space a unique global ecosystem. Earth is the only planet known to maintain life.
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