Water is one of the strongest and most persistent forces on the planet. It can cut through rock or any other obstacle given enough time.

If the water were a human, you might say that its greatest strength comes from the fact that it is lazy. Water always takes the easiest path, even if it isn’t entirely obvious at first glance.

That is why rivers always travel from higher elevations to those that are lower. When the water runs into something hard or more elevated, it will go around it (until it eventually cuts through that hard object).

This is a basic rule in geography, but the Green River doesn’t seem to follow that rule. On a map, you can see the Green River winding its way along normally until it hits the Uinta Mountains in Utah.

At this point, any geologist would expect that it would begin cutting south around the mountains since that is what would take it downhill.

Unexpectedly, however, it just keeps going, cutting a path right through the massive mountains until it emerges on the other side and meets up with the Colorado River.

This river created a 700-metre (2296-foot) canyon through the mountain rather than taking what appears to be the easy path around. For many years, this has been a mystery to those who have studied it, but researchers think they have now figured it out.

In a study published in the Journal of Geophysical Research: Earth Surface, a team looked into a concept known as lithospheric dripping, which is when mountains subside and rebound over time. This is a process that takes millions of years.

Researchers used seismic imaging, advanced modeling, and other techniques to analyze the changes in the region around this river.

They were able to find specific patterns in the mountain and in the crust below that indicated that there was ‘missing’ rock along the path of the river.

This indicates that at some point in the past, the path that the river takes sagged downward into the mantle. Thi sis likely when the river established the course that it is on today.

Over the course of millions of years, the mountain range in that area was pushed back through geological processes, but these processes were very slow. As the mountain ‘grew’, the river kept cutting it away in the path it was taking.

This excruciatingly long ‘battle’ between the mountain and the river is likely ongoing, but at this point, the river has been winning for a long time, and that is not likely to change anytime soon.

Dr. Adam Smith is the lead author of the study and works at the University of Glasgow’s School of Geographical & Earth Sciences. He commented on the study, saying:

“For about 150 years now, geologists have debated over exactly how the rivers merged, which is a particularly challenging question for a tectonically inactive area where major geological events are rarer. We think that we’ve gathered enough evidence to show that lithospheric drip, which is still a relatively new concept in geology, is responsible for pulling the land down enough to enable the rivers to link and merge.”

The rivers that he is talking about are the Green River and the Colorado.

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