New research may have solved an American mystery which has baffled geologists for a century and a half: How did a river carve a path through a mountain in one of the country's most iconic landscapes? Scientists have long sought an answer to this question of how the Green River, the largest tributary of the Colorado River, managed to create a 700-meter-deep canyon through Utah's 4km-high Uinta Mountains instead of simply flowing around them. The question is particularly confounding because, while the Uinta Mountains are 50 million years old, the Green River has been following this route for less than 8 million years.
[...]
"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."
Lithospheric drips occur when dense, mineral-rich material forms at the base of the crust, eventually becoming heavy enough to sink into the mantle below. As they sink, they can drag down the land above them, pulling parts of mountain ranges downward.
When the drip breaks off and continues to sink on its own, the mountain range rebounds, leaving behind a distinctive "bullseye"-patterned zone of uplift across the landscape above the drip's point of origin.
In the new paper, the team show how they used a combination of seismic imaging and sophisticated data modeling to reach their conclusion. Seismic imaging is a process similar to a CT scan which helps scientists "see" below the planet's surface by collecting data on how seismic waves move and are reflected during earthquakes. Researchers from University College London, the University of Utah, and the Utah Geological Survey contributed to the research and co-authored the paper.
By looking at previously published seismic imaging studies of the mountains, the team identified a cold, round anomaly about 200 km below the surface. This mass, which is between 50 and 100km across, is likely to be the broken-off section of the drip, the researchers say.
By estimating how far the drip had fallen and calculating the speed of its descent, the researchers estimate that the drip broke off between 2 and 5 million years ago. Their estimates match well with previous research that estimated the likely period of time during which the Green River cut through the mountains and integrated with the Colorado system.
[...]
Using modeling of the river networks, they identified and measured the bullseye pattern of uplift around the mountains—the telltale "fingerprint" of a lithospheric drip. They also found that the crust beneath the Uinta Mountains is several kilometers thinner than expected for a mountain range of its height, which the team say is consistent with dense lower-crustal material having dripped away. When they calculated the surface uplift expected from this missing material, it matched the roughly 400-plus-meter elevation change they had inferred from the river networks.
It's wild to think of the crust of the earth as a very slow analogue to vapor condensing on the lid of a pot of boiling water, with little drops of water falling back into the pot below.
It's wild to think of the crust of the earth as a very slow analogue to vapor condensing on the lid of a pot of boiling water, with little drops of water falling back into the pot below.
Huh, little confused here. Because I was looking at Google Maps and noticed that the Green River does appear to flow around the Uinta Mountains. Even Wikipedia's description of the river's course...
Huh, little confused here. Because I was looking at Google Maps and noticed that the Green River does appear to flow around the Uinta Mountains.
Even Wikipedia's description of the river's course in Utah, mentions it goes around the Uintas:
South of the [Flaming Gorge] dam, it is forced to turn sharply eastward by the uplift of the Uinta Mountains, looping around the eastern tip of the range as it travels from Utah into northwestern Colorado and through Browns Park before turning west and then south into Dinosaur National Monument, where it passes through the Canyon of the Lodore (otherwise known as the Gates of Lodore) and is joined by the Yampa River at Steamboat Rock. It turns westward back into Utah along the southern edge of the Uintas in Whirlpool Canyon. In Utah, it meanders southwest across the Yampa Plateau and through the Uintah and Ouray Indian Reservation and the Ouray National Wildlife Refuge.
But hey I'm no geologist. Either way, fascinating stuff!
I'm not sure why it says that, given that, for example, Zenobia Peak is east of Green River and still in the Uinta Mountains. The page for the Unitas says this: But then it also says this:...
I'm not sure why it says that, given that, for example, Zenobia Peak is east of Green River and still in the Uinta Mountains.
The page for the Unitas says this:
The Green River used to flow into the Mississippi River to the Gulf of Mexico, but changed to the Colorado River by going through the Uintas in ways not fully understood.[9]
But then it also says this:
The Green is the major tributary of the Colorado River and flows in a tight arc around the eastern side of the range.
Probably just people going based off of vague sources. Your quote seems to possibly be based on a quote similar to this one from my link above:
Now, the Green flows toward the Uintas, then parallels them, and then turns and crosses their eastern flank, eventually joining the Colorado River in Canyonlands National Park. The modern cutting of the Green River through the eastern Uintas intrigued geologist and explorer John Wesley Powell, and has been described as the “classic conundrum” of drainage anomalies. Although the story is complex and not fully understood, a combination of antecedence, superimposition, and stream capture is suspected.
So the source says "crosses their eastern flank," whereas yours says "looping around the eastern tip of the range."
I could see how someone would take "crossing a flank" to mean "looping around a tip" when it's supposed to mean it literally crosses through at the flank.
Hey you're back! I hadn't see your username in awhile. Yeah that checks out. I do think looking at the map makes it look misleading, too. But I think that's my expectation; it's what I'm seeing in...
Hey you're back! I hadn't see your username in awhile.
Yeah that checks out. I do think looking at the map makes it look misleading, too. But I think that's my expectation; it's what I'm seeing in my head. When I hear "cuts through the mountains," I'm thinking it goes like right through them. Of course, just because the river doesn't go through the "main" part of the range, where the highest peaks are, that doesn't mean the area it flows through isn't still part of the Uinta Mountains, even if it is lower relative to the main body of the range.
All this talk about Utah's geography makes me miss it. Been a long time since I've been through that part of the state.
Yep, I had an issue with Three Cheers that I knew how to fix, but just...never did because I also felt like hiding from the site for a while lol It really is a beautiful state. I've only been...
Yep, I had an issue with Three Cheers that I knew how to fix, but just...never did because I also felt like hiding from the site for a while lol
It really is a beautiful state. I've only been there once, but it was quite incredible in the little area I was in just south of the Uintas. Too bad regions like that are totally not intended for human habitation.
From the article:
[...]
[...]
It's wild to think of the crust of the earth as a very slow analogue to vapor condensing on the lid of a pot of boiling water, with little drops of water falling back into the pot below.
Huh, little confused here. Because I was looking at Google Maps and noticed that the Green River does appear to flow around the Uinta Mountains.
Even Wikipedia's description of the river's course in Utah, mentions it goes around the Uintas:
But hey I'm no geologist. Either way, fascinating stuff!
I'm not sure why it says that, given that, for example, Zenobia Peak is east of Green River and still in the Uinta Mountains.
The page for the Unitas says this:
But then it also says this:
Probably just people going based off of vague sources. Your quote seems to possibly be based on a quote similar to this one from my link above:
So the source says "crosses their eastern flank," whereas yours says "looping around the eastern tip of the range."
I could see how someone would take "crossing a flank" to mean "looping around a tip" when it's supposed to mean it literally crosses through at the flank.
Hey you're back! I hadn't see your username in awhile.
Yeah that checks out. I do think looking at the map makes it look misleading, too. But I think that's my expectation; it's what I'm seeing in my head. When I hear "cuts through the mountains," I'm thinking it goes like right through them. Of course, just because the river doesn't go through the "main" part of the range, where the highest peaks are, that doesn't mean the area it flows through isn't still part of the Uinta Mountains, even if it is lower relative to the main body of the range.
All this talk about Utah's geography makes me miss it. Been a long time since I've been through that part of the state.
Yep, I had an issue with Three Cheers that I knew how to fix, but just...never did because I also felt like hiding from the site for a while lol
It really is a beautiful state. I've only been there once, but it was quite incredible in the little area I was in just south of the Uintas. Too bad regions like that are totally not intended for human habitation.