Jakarta –
Geologists have finally found a strong explanation for the winding path of the Green River in Utah, United States, which looks like it flows up ‘through’ the mountains. This phenomenon has been a scientific puzzle for more than a century.
This river cuts through the Uinta Mountains and forms Lodore Canyon about 700 meters deep. In fact, according to topographic logic, water should flow around the mountain, not through its peak.
The Green River is the largest tributary of the Colorado River, flowing for hundreds of miles in Wyoming and Utah before joining Canyonlands National Park. If you look at the map, this river looks as if it ‘rises’ through the mountains. But scientists explain that it is not a river that truly defies gravity. Instead, this phenomenon occurs due to topographic changes on a geological scale.
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New research published in the Journal of Geophysical Research: Earth Surface shows that the basis of this puzzle is most likely a phenomenon called lithospheric drip, which is a geological process in which very dense material at the base of the Earth’s crust slowly drops into the deeper mantle, pulling and lowering parts of the surface above it before bouncing back up.
According to Dr. Adam Smith, lead researcher from the School of Geographical & Earth Sciences, University of Glasgow, this process explains how the Green River can pass south of the Uinta Mountains.
“For about 150 years now, geologists have debated how rivers merge, which is a challenging question in a tectonically inactive area. We think we have gathered enough evidence to show that lithospheric drip pulls on the soil enough to allow rivers to connect and merge,” explained Smith as quoted in Popular Science.
An Anomaly
Based on seismic reconstruction and modeling data, the research team discovered a cold circular anomaly beneath the Uinta Mountains, about 200 km below the surface. This anomaly is thought to be the remainder of the ‘drip’ solid material, which has been released and descended into the mantle.
When this phenomenon occurred millions of years ago, the land above it also fell, creating a lower path for the river to flow. This process is thought to have occurred between 2 and 5 million years ago, corresponding to the age when the Green River likely began cutting its way through the mountains and eventually connecting with the Colorado River.
This discovery shows that river channels that appear to be flowing upward are actually happening because the ridges of the mountains have fallen temporarily, rather than water flowing from bottom to top.
This research also rejects several previous hypotheses which stated that the river may have existed before the mountains or was formed by the accumulation of sediment high enough to make the river ‘spill’ over the mountains.
New geological and modeling evidence strongly supports a lithospheric drip mechanism as the primary cause of this unusual river path. The findings help solve one of North America’s longest-standing geomorphological mysteries and show that geological processes in the deep Earth can dramatically change the surface landscape, including the flow paths of large rivers that cut through mountains.
(rns/rns)
