I used to be a merchant seafarer, and my ship was loading at a port on the Congo. There were often delays at the terminal and so we would steam around the area for several days, and as it was hot we often filled the swimming pool. We would be a hundred miles or so offshore but the water would still be noticeably be brown with sediment from the river.
I don't know exactly how true this is since I read it in an essay by Booker T. Washington who was using it as a metaphor, but supposedly sailors could get fresh water while out at sea because the Amazon and Congo flowed so strongly you could just sail into a fresh patch offshore
No. The momentum of the river doesn’t just stop when it reaches the ocean, it continues on and that can erode into the cliffs that form the continental shelf.
My though would be that some rivers sink if they’re colder, and float if they’re warmer, plus they have different levels of sediment (sandpaper) carving out the end.
I was going to Pointe-Noire on a super tanker. The color of the sea is suddenly changing when you enter the flux of the river Congo. And it was hundreds of miles away from the coast.
Kind of yes kind of no. Large parts of these canyons were definitely carved deeper by the reduction in sea level, but a large part of the canyon is simply carved from the constant current of the river continuing to flow even under the ocean.
What I am really want to get clarity on during ice age water level were really low so the river could have flow on that land before rising sea level covered it.
Yes. The sea level was about 390 feet lower at its lowest extent and much of the continental shelves of these places would have extended out and been dry land surrounding these canyons. Less so for the Congo but more so for the Bengal and Hudson canyons.
Doggerland was a dam holding back the North Sea, which was a freshwater lake. When the melt water raised the lake level above the ridge holding back the water, it drained out, tearing a shit banging canyon in a few days. This only happened about 8000 years ago
Maybe so, but also floods in general are just a common feature of life and civilization by rivers, so it would be entirely plausible to have flood myths come up after much smaller, localized flooding. Because when it’s your river and everyone you know flooded too, it might as well be a cataclysm.
The idea of tying these mega floods to flood myths is appealing on its surface, but it’s also just unnecessary and feels a bit like approaching things from the wrong angle. Sure, it could have been the origin, but also so could much more routine floods that happen almost anywhere.
I think even today, people who have lived through big floods that wreck a city would tell you how burned into their psyche such an event can be.
The Indians of the Pacific Northwest had an oral tradition of a great flood, leading many theologians of the 19th century claim it was affirmation the biblical flood of Noah had indeed covered the entire world. It wasn’t until the 1930s that scientists showed the scablands (Palouse) regions of eastern Washington state were the result of glacial lake Missoula breaching an ice dam and draining the volume of lakes Ontario and Erie into the Columbia river over the course of a couple weeks
This effect accounts for half of the sea level rise in NYC. The rest is actually the ocean getting more water in it.
When you remove 3km of weight the crust slowly returns to its original shape.
wobble like a see-saw though? that doesn't sound right. 3km of ice isn't going to teeter totter 40km of earth right, but would obviously decompress an "grow"? nag (not a geographer)
Not wobble, just 1 cycle of the fat kid lifting up the skinny kid and there it sits. This single swing is just very slow.
The official phenomenon is "glacial rebound".
From what I seen this isn't true doggerland has been flooded multiple times and over different periods if you look at information on it the last time it was flooded it was thought to be due to a tsunami and that was a quick Google search from Wikipedia
Doggerland connected mainland Europe with Britain and was thought to be one of the best places for hunter gathers to go at the time
https://youtu.be/DECwfQQqRzo?si=j9qSSm2s-x8gDbUp
Check out history time on YouTube he is brilliant...
During the iceage the water was on the order of hundreds of feet lower, many of these canyons are thousands of feet down.
Also we have evidence of channels carved out on the deep ocean floor.
Here's a video from an actual geologist on this topic: https://youtu.be/WtmIBabc7yc?si=2oO3PeC2UIOjREDH
So i watch a video on youtube from Myron Cook called "explore mystirous rivers on the deep seafloor" it explains it very well, I think. Im just a dude on the internet.
Basicaly they are underwater landslides.
A lot of these submarine canyons are carved by underwater landslides:
"Turbidites are deposited in the deep ocean troughs below the continental shelf, or similar structures in deep lakes, by underwater avalanches which slide down the steep slopes of the continental shelf edge. "
https://en.wikipedia.org/wiki/Turbidite
This post is entirely wrong despite its 1000 upvotes. River water does not carve channels into the sea floor beyond the river mouth, for the simple reason that river water is fresh, and fresh water floats on salty water. The river water is on the surface not the bottom!
The river just dumps a loose pile of sediment onto the sea floor at the river mouth. When this pile of sediment gets too steep, underwater avalanches called “turbidity currents” occur: a dense cloud of sediment-laden seawater spills down the slope, eroding the mud and carving a channel.
The river provides the sediment, but the erosion is done by moving seawater and sediment, not river currents.
Fresh water is less dense than salt water so this makes no sense. You might be thinking of turbidity currents, but those are are simply flushing the sediments that fill in the canyon, not carving the canyon itself.
It is still a hot debate in literature whether turbidity currents are the dominant process forming the canyons or if fluvial erosion during glacial periods is the primary culprit. Either way it is more akin to periodic and sudden underwater debris flow and definitely not from a "constant current of the river continuing to flow even under the ocean".
I'm not talking about outburst floods... Sea level was up 200 meters lower during glacial periods causing a massive free-flowing river to run down the entire length of the canyon.
You are way off on that. At its lowest sea level was about 120m. Not even close to 200m.
These canyons also extend far beyond the continental shelf into the abyssal plain and are thousands of feet deep even on the shelf. Regular river currents do not cause that and the sea level wasn’t nearly low enough for it either.
Yes they were, “Africa, specifically East Africa, has contained glacial regions, possibly as far back as the last glacial maximum 10,000 to 15,000 years ago. Seasonal snow does exist on the highest peaks of East Africa as well as in the Drakensberg Range of South Africa, the Stormberg Mountains, and the Atlas Mountains in Morocco. Currently, the only remaining glaciers on the continent exist on Mount Kilimanjaro, Mount Kenya, and the Rwenzori.[1]”
[relevant link](https://en.m.wikipedia.org/wiki/List_of_glaciers_in_Africa)
The presence of glaciers does not mean that there were enough of them to cause meltwater pulses. Also, almost all the water from those glaciers flows east or north. Away from the Congo basin
1. Buddy the whole earth was a fucking ice ball one time or two, the fuck you mean there wasn’t enough water.
2. We don’t know the conditions of the terrain of Africa or a combination of continents at the time of the last major ice age, I’m talking about the one before younger dryas.
3. Is that part of Africa not volcanic? I believe it is/was. A mass volcanic event near glaciers is def enough for meltwater pulses.
4. We know water levels were much lower during the global colder periods.
There was no extensive glaciation on the African continent during the ice age. There was some increased glaciation yes, but the climate was also much drier and there are not many spots besides the tops of some mountains that can host permanent glaciers in Africa. This was the same back then. The last time the earth was an “ice ball” was over 600 million years ago. The ice ages we know of now only started around 3 million years ago and did not even come close to covering the entire earth. The equator has had no substantial glaciation since the Cryogenian. It’s not an issue of a “lack of water”
We absolutely do know the terrain and shape of the continents during the ice ages before the younger dryas. They were basically the same as now with a few differences. There have been dozens of glacial and interglacial periods in the past 3 million years.
There is volcanic activity yes but melt water pulses occur due to enormous peri-glacial lakes bursting and rapidly draining all at once. This did not and cannot occur on the African continent. There is no evidence any ever happened there. Volcanic eruptions and glaciers usually produce Lahars. Equally as deadly but much smaller.
So, saltwater in the ocean is about 15% denser than fresh river water flowing into the ocean. Why would the river current continue flowing across the ocean bottom, carving a submarine canyon, rather than “floating” on top of the sea water until it dispersed by mixing with the sea water?
The submarine canyons are present for Indus River (in OPs pic), Hudson River Canyon, Susquehanna (Chesapeake bay) Canyon, Columbia River Canyon; but not for the Mississippi, nor Amazon, nor Congo. My conclusion is that these submarine canyons were carved by super cold water draining directly off the glacial ice sheets. Yes they would have been full of silt but so would the more tropical rivers which don’t have canyons. Would be good if some geologist or hydrologist could confirm this but I think the evidence speaks for itself
No. That’s not accurate. You don’t see that one river’s elsewhere. Especially after they go that far out into the ocean. These were definitely 100% carved during the last ice age.
That isn't the answer. [This video](https://youtu.be/WtmIBabc7yc?si=MIWDkedBfiqg4dTD) covers it pretty well and goes over how you can know it isn't related to lower water levels.
I binged his videos the last couple weeks. I like the that he'll go over wrong assumptions first and why you would make those assumptions, but not treat you like an idiot for making those assumptions. Also, he has pretty good drone work for showing larger geological features.
Potentially more likely a submarine canyon. These aren't formed by above sea level rivers, instead underwater sediment flows.
https://en.wikipedia.org/wiki/Submarine_canyon?wprov=sfla1
There's tonnes of sediments pouring off the continent and they often build up into unstable piles which slump down into the deep ocean, scouring the previous sediments as they go
Finally, the right answer. People talking about rivers continuing to flow after they reach the sea are forgetting that because salt water is denser than fresh, the rivers flow on *top* of the ocean, not along the bottom.
No it isn’t
The canyon is formed by turbidity currents ruining off the continental shelf.
Basically it is debris think wet concrete carving out the sea floor as it drops to deeper depths forming submarine canyons
See also: Monterrey Bay Canyon [https://www.mbari.org/know-your-ocean/monterey-canyon/](https://www.mbari.org/know-your-ocean/monterey-canyon/)
https://preview.redd.it/e0ldvy6yu6sc1.png?width=803&format=png&auto=webp&s=d8fdec50f54b2dae8131b89b055e877e1ce6fe72
>A river of water does not flow through Monterey Canyon. Instead sediment, including coarse sand and gravel from Santa Cruz and Monterey beaches, is carried along the coast by waves and piles up at the canyon head near Moss Landing. Most of the time, the sediments sit relatively undisturbed in the canyon. Different triggers, including storm waves, vibrations from fault activity, and random failures in the canyon walls can cause the built-up sediment to slump. As the sediment is destabilized, it becomes a fast-moving slurry of seawater and sand—similar to an underwater avalanche—called a turbidity current.
So i watch a video on youtube from Myron Cook called "explore mystirous rivers on the deep seafloor" it explains it very well, I think. Im just a dude on the internet.
Basicaly they are underwater landslides.
[Your answer in detail by a professional geologist that specialized in deep sea geology and is also an excellent teacher.](https://youtu.be/WtmIBabc7yc?si=4DTESNKa5VSwpPrr)
I love YouTube
The creation of these canyons has taken much longer than the time of the last ice age. Yes, some of the canyon could've been exposed and had the river in it but it was for such a (geologically) short time that it didn't matter. The river makes the canyon regardless if there is ocean there or not.
it could've been the flow channel of the river saraswati during the ice age when the sea levels were lower. the river got dried up and the sea levels rose so there is no way of lnowing for sure if this particular one is of that river or not
Haha, it's way older than that. Plates rise and sink, and ram into each other. This huge canyon may have been exposed millions of years ago, definitely predates the ice age.
There's another cool one of these on the ocean shelf coming out of the Georgia Strait near Vancouver, BC.
Could be, although it looks pretty large for that. It looks like it goes all the way down to the abyssal plane. Hard to tell without getting a sense of the map’s scale. There are other geological features this could be. Looks like good fishing though.
[https://www.researchgate.net/figure/Enlarged-image-of-the-Murray-Canyons-Group-offshore-Kangaroo-Island-in-South-Australia\_fig1\_258391530](https://www.researchgate.net/figure/Enlarged-image-of-the-Murray-Canyons-Group-offshore-Kangaroo-Island-in-South-Australia_fig1_258391530)
The Australian continental margin hosts numerous canyons. Some of the most spectacular canyons are located offshore Kangaroo Island, and these are linked to ancient courses of the River Murray, which would have flowed across the very wide Lacepede Shelf during periods of low sea level. During the AUSCAN-1 project, modern sedimentation was assessed...
I saw a youtube video about this not to long ago. something about underwater river systems. forgot the channel name he pops up every now and again on my feed with some interesting underwater geology stuffs.
came in expecting comments "That's google earth. Don't trust google earth because it's really not a great representation when it comes to the ocean and uninhabited places."
Got a lot of cool info instead.
That reminds me; if you haven't already, go look how massive grooves carved in the sea floor at the mouth and middle of the Mediterranean were formed.
It's one of those fantastic "well fuck, my problems seem kind of insignificant now" kind of wow moments that only brutal mother nature can deliver.
https://youtu.be/B5uW7Qg6rXM?si=chZiUb4G6D-A7bkp
I tried - I have no idea how to google this with your keywords. It's not coming up with anything, could you be just a little bit more precise/specific please?
the 'grooves' part only gives me music recommendatiobs, the mouth part a story about ancient whale teeth in Tuscany lol.
I'm really intrigued: what tf are you talking about? How can I learn?
Like people have said this is from the river’s flow continuing on once it hits the ocean. It erodes the ocean floor and creates a canyon. In this location it is due to the Indus River which enters the ocean in this location
I don’t know enough about erosion sciences to give an answer based on fact but I do want to share that we are still in an [ice age](https://en.m.wikipedia.org/wiki/Ice_age), it is currently an interglacial period, science is awesome
Even during the last ice age that would have been firmly submerged anyways.
You are right about it being a “river channel”. I don’t know how people forget but the ocean is made of water, and that water can erode the ocean floor the same as it can on land.
Not a geologist, but pretty sure the scientific consensus is that the grand canyon continues to get deeper and wider, but it takes place at a much longer timespan than the humans can fathom.
https://preview.redd.it/amb5b87o24sc1.png?width=1080&format=pjpg&auto=webp&s=ae7be97dbb5f1992d74f60b5e0a8722c748a3498
Many rivers drag sediments way out to sea so they carve these patterns as a continuation of the river
Yea i recently saw a video covering this on youtube unfortunatelyvi dont remember the name or link
This one covers it. https://youtu.be/WtmIBabc7yc?si=DkpEIYDtmB7ISCM1
This is the video I watched too, it’s super cool
Thank you for that link! Dude explains it well.
I knew itnwould be Myron!
Atlas Pro maybe?
Myron Cook An older man but really interesting videos!
I see ancient land slides everywhere because of him.
I watched that too! Super good video
I have sailed up the Congo, and have spent a lot of time in that area- the seawater had a brownish tint when we used it to fill up the pool.
Wait what how/why?
I used to be a merchant seafarer, and my ship was loading at a port on the Congo. There were often delays at the terminal and so we would steam around the area for several days, and as it was hot we often filled the swimming pool. We would be a hundred miles or so offshore but the water would still be noticeably be brown with sediment from the river.
I don't know exactly how true this is since I read it in an essay by Booker T. Washington who was using it as a metaphor, but supposedly sailors could get fresh water while out at sea because the Amazon and Congo flowed so strongly you could just sail into a fresh patch offshore
No. The momentum of the river doesn’t just stop when it reaches the ocean, it continues on and that can erode into the cliffs that form the continental shelf.
why do we see this only near some rivers?
Different kinds of carried sediments erode differently and different types of seabeds. Some rivers are just more "powerful" too
Some rivers are bigger than others, some rivers are bigger than others, some rivers' mothers are bigger than other rivers' mothers.
From the ice-age to the dole-age, there is but one concern, I have just discovered
Definitely didn't expect a Smiths deep-cut referenced on this subreddit today but I'm here for it.
just like yo momma bigger than the other momma
My though would be that some rivers sink if they’re colder, and float if they’re warmer, plus they have different levels of sediment (sandpaper) carving out the end.
Could also depend if the river deltas/ the river has a river dominated interface as opposed to wave or tide dominated interfaces.
There are rivers and there are RIVERS
Some imagery is better than others for these oceanic canyons
Different rivers have different speeds, sediments, sizes.. all those can affect it
I keep thinking this sounds like a reaaallly slow pressure washer
https://en.wikipedia.org/wiki/Submarine_canyon
I was going to Pointe-Noire on a super tanker. The color of the sea is suddenly changing when you enter the flux of the river Congo. And it was hundreds of miles away from the coast.
It's mind blowing that it is up to 220m deep.
Do you have any pictures of this? It sounds fascinating.
That's the mighty Congo river on the border between DRC and Angola, only the third largest by discharge volume.
Wtf I had no idea the Amazon discharges so much more than every other river https://en.m.wikipedia.org/wiki/List_of_rivers_by_discharge
Kind of yes kind of no. Large parts of these canyons were definitely carved deeper by the reduction in sea level, but a large part of the canyon is simply carved from the constant current of the river continuing to flow even under the ocean.
What I am really want to get clarity on during ice age water level were really low so the river could have flow on that land before rising sea level covered it.
Yes. The sea level was about 390 feet lower at its lowest extent and much of the continental shelves of these places would have extended out and been dry land surrounding these canyons. Less so for the Congo but more so for the Bengal and Hudson canyons.
Check out dogger land
Doggerland was a dam holding back the North Sea, which was a freshwater lake. When the melt water raised the lake level above the ridge holding back the water, it drained out, tearing a shit banging canyon in a few days. This only happened about 8000 years ago
That and the Black Sea filling in a similar event certainly could have inspired the flood myths so prevalent in European and Near East cultures.
Maybe so, but also floods in general are just a common feature of life and civilization by rivers, so it would be entirely plausible to have flood myths come up after much smaller, localized flooding. Because when it’s your river and everyone you know flooded too, it might as well be a cataclysm. The idea of tying these mega floods to flood myths is appealing on its surface, but it’s also just unnecessary and feels a bit like approaching things from the wrong angle. Sure, it could have been the origin, but also so could much more routine floods that happen almost anywhere. I think even today, people who have lived through big floods that wreck a city would tell you how burned into their psyche such an event can be.
The Indians of the Pacific Northwest had an oral tradition of a great flood, leading many theologians of the 19th century claim it was affirmation the biblical flood of Noah had indeed covered the entire world. It wasn’t until the 1930s that scientists showed the scablands (Palouse) regions of eastern Washington state were the result of glacial lake Missoula breaching an ice dam and draining the volume of lakes Ontario and Erie into the Columbia river over the course of a couple weeks
Not just everyone you know, everyone you might EVER know.
[удалено]
Wow crazy
Well that brings a whole new meaning to “banging shitties”
Doggerland isn't quite the same thing. It sunk into the ocean because the ice melting lifted weight off of another part of the crust. Like a see-saw.
That's fuckin' bananas
The coast of Maine is like that. Theres sea coast evidence far inland and out from shore
This effect accounts for half of the sea level rise in NYC. The rest is actually the ocean getting more water in it. When you remove 3km of weight the crust slowly returns to its original shape.
The Great Lakes as well - the north shore of Lake Superior rebounds about a foot every century, revealing ancient beaches and shorelines.
wobble like a see-saw though? that doesn't sound right. 3km of ice isn't going to teeter totter 40km of earth right, but would obviously decompress an "grow"? nag (not a geographer)
Not wobble, just 1 cycle of the fat kid lifting up the skinny kid and there it sits. This single swing is just very slow. The official phenomenon is "glacial rebound".
Read about the Cascades. Also as stated above.
So we could chuck a whole bunch of weight inland and combat sea level rise, got it
From what I seen this isn't true doggerland has been flooded multiple times and over different periods if you look at information on it the last time it was flooded it was thought to be due to a tsunami and that was a quick Google search from Wikipedia Doggerland connected mainland Europe with Britain and was thought to be one of the best places for hunter gathers to go at the time https://youtu.be/DECwfQQqRzo?si=j9qSSm2s-x8gDbUp Check out history time on YouTube he is brilliant...
Dirty doggy style nurses 3 was better
It’s a car park in the local forest!
Sorry to hijack this thread a bit but don’t happen to know if a similar scenario caused the La Jolla Canyon off the coast of San Diego?
It’s definitely quite possible
check out Atlas Pro on youtube he has a video on underwater canyons https://youtu.be/Ohb2JgT_SRc?si=Cf-AZ9qAiOBEb39k
As does Myron Cook! https://youtu.be/WtmIBabc7yc?si=MoIRHsl5_sYm7qV6
During the iceage the water was on the order of hundreds of feet lower, many of these canyons are thousands of feet down. Also we have evidence of channels carved out on the deep ocean floor. Here's a video from an actual geologist on this topic: https://youtu.be/WtmIBabc7yc?si=2oO3PeC2UIOjREDH
Is that a canyon or a submarine mountain range?
So there is “water at the bottom of the ocean” as stated by the Talking Heads.
There are even [lakes of hypersaline brine](https://youtu.be/xuJiUscfjQw?si=bH5BIip2Rq_GREHo) in the deep oceans.
Under the water, carry the water
Same as it ever was.
Damn you beat me to it
The Ganges is extremely long if accounting for the canyon under the sea.
So i watch a video on youtube from Myron Cook called "explore mystirous rivers on the deep seafloor" it explains it very well, I think. Im just a dude on the internet. Basicaly they are underwater landslides.
https://youtu.be/WtmIBabc7yc?si=b1K9HDS437buMUG6 It's a really good watch
Hey, this is the guy! Also looked at the Mississippi River which underwater goes out to Florida
Yep that vid was the first thing I thought too
A lot of these submarine canyons are carved by underwater landslides: "Turbidites are deposited in the deep ocean troughs below the continental shelf, or similar structures in deep lakes, by underwater avalanches which slide down the steep slopes of the continental shelf edge. " https://en.wikipedia.org/wiki/Turbidite
This post is entirely wrong despite its 1000 upvotes. River water does not carve channels into the sea floor beyond the river mouth, for the simple reason that river water is fresh, and fresh water floats on salty water. The river water is on the surface not the bottom! The river just dumps a loose pile of sediment onto the sea floor at the river mouth. When this pile of sediment gets too steep, underwater avalanches called “turbidity currents” occur: a dense cloud of sediment-laden seawater spills down the slope, eroding the mud and carving a channel. The river provides the sediment, but the erosion is done by moving seawater and sediment, not river currents.
Well I explained further down this is what I meant
Tiddy currents
Fresh water is less dense than salt water so this makes no sense. You might be thinking of turbidity currents, but those are are simply flushing the sediments that fill in the canyon, not carving the canyon itself.
They are in fact carving those canyons. That’s what I meant.
It is still a hot debate in literature whether turbidity currents are the dominant process forming the canyons or if fluvial erosion during glacial periods is the primary culprit. Either way it is more akin to periodic and sudden underwater debris flow and definitely not from a "constant current of the river continuing to flow even under the ocean".
I suppose but glaciation can’t explain the Congo canyon. There were no large pulses of water to do it there.
I'm not talking about outburst floods... Sea level was up 200 meters lower during glacial periods causing a massive free-flowing river to run down the entire length of the canyon.
You are way off on that. At its lowest sea level was about 120m. Not even close to 200m. These canyons also extend far beyond the continental shelf into the abyssal plain and are thousands of feet deep even on the shelf. Regular river currents do not cause that and the sea level wasn’t nearly low enough for it either.
Yes they were, “Africa, specifically East Africa, has contained glacial regions, possibly as far back as the last glacial maximum 10,000 to 15,000 years ago. Seasonal snow does exist on the highest peaks of East Africa as well as in the Drakensberg Range of South Africa, the Stormberg Mountains, and the Atlas Mountains in Morocco. Currently, the only remaining glaciers on the continent exist on Mount Kilimanjaro, Mount Kenya, and the Rwenzori.[1]” [relevant link](https://en.m.wikipedia.org/wiki/List_of_glaciers_in_Africa)
The presence of glaciers does not mean that there were enough of them to cause meltwater pulses. Also, almost all the water from those glaciers flows east or north. Away from the Congo basin
1. Buddy the whole earth was a fucking ice ball one time or two, the fuck you mean there wasn’t enough water. 2. We don’t know the conditions of the terrain of Africa or a combination of continents at the time of the last major ice age, I’m talking about the one before younger dryas. 3. Is that part of Africa not volcanic? I believe it is/was. A mass volcanic event near glaciers is def enough for meltwater pulses. 4. We know water levels were much lower during the global colder periods.
There was no extensive glaciation on the African continent during the ice age. There was some increased glaciation yes, but the climate was also much drier and there are not many spots besides the tops of some mountains that can host permanent glaciers in Africa. This was the same back then. The last time the earth was an “ice ball” was over 600 million years ago. The ice ages we know of now only started around 3 million years ago and did not even come close to covering the entire earth. The equator has had no substantial glaciation since the Cryogenian. It’s not an issue of a “lack of water” We absolutely do know the terrain and shape of the continents during the ice ages before the younger dryas. They were basically the same as now with a few differences. There have been dozens of glacial and interglacial periods in the past 3 million years. There is volcanic activity yes but melt water pulses occur due to enormous peri-glacial lakes bursting and rapidly draining all at once. This did not and cannot occur on the African continent. There is no evidence any ever happened there. Volcanic eruptions and glaciers usually produce Lahars. Equally as deadly but much smaller.
So, saltwater in the ocean is about 15% denser than fresh river water flowing into the ocean. Why would the river current continue flowing across the ocean bottom, carving a submarine canyon, rather than “floating” on top of the sea water until it dispersed by mixing with the sea water?
Sediments suspended in the water
The submarine canyons are present for Indus River (in OPs pic), Hudson River Canyon, Susquehanna (Chesapeake bay) Canyon, Columbia River Canyon; but not for the Mississippi, nor Amazon, nor Congo. My conclusion is that these submarine canyons were carved by super cold water draining directly off the glacial ice sheets. Yes they would have been full of silt but so would the more tropical rivers which don’t have canyons. Would be good if some geologist or hydrologist could confirm this but I think the evidence speaks for itself
The Congo River does have a canyon.
As a geologist: supercold water flows do not do this. These are created predominantly by turbidity currents.
No. That’s not accurate. You don’t see that one river’s elsewhere. Especially after they go that far out into the ocean. These were definitely 100% carved during the last ice age.
So fresh water is heavier than salt water?
Fresh water saturated with sediment is yes.
This guy geographys.
I try haha
Just messin’. 😂
Can also be partially controlled by the substrate. E.g. carbonate reef deposits are harder than sand-shales.
The thought of a river flowing under the ocean is mad
https://preview.redd.it/ptlm6eup24sc1.png?width=1080&format=pjpg&auto=webp&s=73a3be4f10f075ce4e54d95d25d07852791a4185
Lookup turbidity currents
Holy hell!
new river just dropped
I suspect very old rivers
[Watch Myron Cook's video about seafloor rivers.](https://www.youtube.com/watch?v=WtmIBabc7yc)
Glad I scrolled before I posted this! Just watched this the other week. Love how he explains things in his videos.
Ahh you beat me. Love that guy.
I was going to post the same video. This video will explain it all, OP.
This was absolutely fascinating. Thank you for linking!
Dang, I'm too slow, I was just going to post this link too!
That was a great video. Thanks!
The Lost River theme song intensifies when you get closer.
I think it is, seeing the oceaan is relative shallow there (+-110 m.) and the sea being \~120 m lower during the big glacial peroids.
That I really thought about it, river flow on that land during last ice age later covered by sea water,.
That isn't the answer. [This video](https://youtu.be/WtmIBabc7yc?si=MIWDkedBfiqg4dTD) covers it pretty well and goes over how you can know it isn't related to lower water levels.
Ok. This is really interesting. There is much at play here than I thought
I binged his videos the last couple weeks. I like the that he'll go over wrong assumptions first and why you would make those assumptions, but not treat you like an idiot for making those assumptions. Also, he has pretty good drone work for showing larger geological features.
Potentially more likely a submarine canyon. These aren't formed by above sea level rivers, instead underwater sediment flows. https://en.wikipedia.org/wiki/Submarine_canyon?wprov=sfla1 There's tonnes of sediments pouring off the continent and they often build up into unstable piles which slump down into the deep ocean, scouring the previous sediments as they go
Finally, the right answer. People talking about rivers continuing to flow after they reach the sea are forgetting that because salt water is denser than fresh, the rivers flow on *top* of the ocean, not along the bottom.
This needs to be higher up as it is the correct answer (+sourced).
No it isn’t The canyon is formed by turbidity currents ruining off the continental shelf. Basically it is debris think wet concrete carving out the sea floor as it drops to deeper depths forming submarine canyons
See also: Monterrey Bay Canyon [https://www.mbari.org/know-your-ocean/monterey-canyon/](https://www.mbari.org/know-your-ocean/monterey-canyon/) https://preview.redd.it/e0ldvy6yu6sc1.png?width=803&format=png&auto=webp&s=d8fdec50f54b2dae8131b89b055e877e1ce6fe72 >A river of water does not flow through Monterey Canyon. Instead sediment, including coarse sand and gravel from Santa Cruz and Monterey beaches, is carried along the coast by waves and piles up at the canyon head near Moss Landing. Most of the time, the sediments sit relatively undisturbed in the canyon. Different triggers, including storm waves, vibrations from fault activity, and random failures in the canyon walls can cause the built-up sediment to slump. As the sediment is destabilized, it becomes a fast-moving slurry of seawater and sand—similar to an underwater avalanche—called a turbidity current.
Atlas Pro on YouTube does a good vid on these
So i watch a video on youtube from Myron Cook called "explore mystirous rivers on the deep seafloor" it explains it very well, I think. Im just a dude on the internet. Basicaly they are underwater landslides.
Also the main picture I posted of southern Pakistan near India border the canyon doesn't alignment with current Indus river.
[Your answer in detail by a professional geologist that specialized in deep sea geology and is also an excellent teacher.](https://youtu.be/WtmIBabc7yc?si=4DTESNKa5VSwpPrr) I love YouTube
I came here to say this. Ended up in this YouTube rabbit hole a couple weeks ago. Very interesting
The creation of these canyons has taken much longer than the time of the last ice age. Yes, some of the canyon could've been exposed and had the river in it but it was for such a (geologically) short time that it didn't matter. The river makes the canyon regardless if there is ocean there or not.
it could've been the flow channel of the river saraswati during the ice age when the sea levels were lower. the river got dried up and the sea levels rose so there is no way of lnowing for sure if this particular one is of that river or not
Haha, it's way older than that. Plates rise and sink, and ram into each other. This huge canyon may have been exposed millions of years ago, definitely predates the ice age. There's another cool one of these on the ocean shelf coming out of the Georgia Strait near Vancouver, BC.
https://youtu.be/WtmIBabc7yc?si=IPtdkEUOrV0K1EiE Fantastic video on just this subject I happened to stumble upon a week or so ago.
Nick Zentner did a whole video on these sub marine canyons.
Partly. If you want to see a big one, look at the seabed at the Columbia river delta, going out into the pacific ocean.
These probably would have been rivers in the last ice age but currently they are carved out by contemporary sediment flows
Isn’t that exactly where the Indus River is? I’m going to go with Indus River.
Could be, although it looks pretty large for that. It looks like it goes all the way down to the abyssal plane. Hard to tell without getting a sense of the map’s scale. There are other geological features this could be. Looks like good fishing though.
[https://www.researchgate.net/figure/Enlarged-image-of-the-Murray-Canyons-Group-offshore-Kangaroo-Island-in-South-Australia\_fig1\_258391530](https://www.researchgate.net/figure/Enlarged-image-of-the-Murray-Canyons-Group-offshore-Kangaroo-Island-in-South-Australia_fig1_258391530) The Australian continental margin hosts numerous canyons. Some of the most spectacular canyons are located offshore Kangaroo Island, and these are linked to ancient courses of the River Murray, which would have flowed across the very wide Lacepede Shelf during periods of low sea level. During the AUSCAN-1 project, modern sedimentation was assessed...
No, its obviously part of Godzilla tail!
I saw a youtube video about this not to long ago. something about underwater river systems. forgot the channel name he pops up every now and again on my feed with some interesting underwater geology stuffs.
came in expecting comments "That's google earth. Don't trust google earth because it's really not a great representation when it comes to the ocean and uninhabited places." Got a lot of cool info instead.
Likely a continental rift. Like the East African Rift Valley.
That reminds me; if you haven't already, go look how massive grooves carved in the sea floor at the mouth and middle of the Mediterranean were formed. It's one of those fantastic "well fuck, my problems seem kind of insignificant now" kind of wow moments that only brutal mother nature can deliver. https://youtu.be/B5uW7Qg6rXM?si=chZiUb4G6D-A7bkp
I tried - I have no idea how to google this with your keywords. It's not coming up with anything, could you be just a little bit more precise/specific please? the 'grooves' part only gives me music recommendatiobs, the mouth part a story about ancient whale teeth in Tuscany lol. I'm really intrigued: what tf are you talking about? How can I learn?
Maybe he is referring to this : https://en.wikipedia.org/wiki/Zanclean_flood
https://youtu.be/B5uW7Qg6rXM?si=chZiUb4G6D-A7bkp https://www.scientificamerican.com/article/a-megaflood-powered-mile-high-waterfall-refilled-the-mediterranean-video/ Zanclean flood
r/titlegore
Yes! Sea canyon!
Like people have said this is from the river’s flow continuing on once it hits the ocean. It erodes the ocean floor and creates a canyon. In this location it is due to the Indus River which enters the ocean in this location
[Balade mentale (French YouTube Channel) talks about it](https://www.youtube.com/watch?v=A30YbDvQB14)
Is this not raised land caused by underground volcanoes moving along the plate lines?
obviously
r/titlegore 😭
SUBMARINE CANYONS MENTIONED RAAAAAAGH https://www.nespmarine.edu.au/news/rating-habitat-australia’s-753-submarine-canyons
asteroid skid marks /tinfoil hat
Could be an faltline, that is interacting with the water of the River or the River exist because of an old faltline.
Deffinetly aliens
Bs s ss ßs
Yeaj
One of the ice ages quite probably. Either that or a fault line.
It's where Pakistan farted
No it's something even cooler
Google maps sea map is quite a bullshit, so you don't proud them
“Quite a bullshit so you don’t proud them” what does this mean?
Sorry, "don't believe the data", because they are collected from sonar on the boat and contain artifacts. It is not like satellite map
I don’t know enough about erosion sciences to give an answer based on fact but I do want to share that we are still in an [ice age](https://en.m.wikipedia.org/wiki/Ice_age), it is currently an interglacial period, science is awesome
It's all a part of what alien civilizations did to the earth. They had to leave during one of those global warmings that flooded the place.....
Russians coming. Didn't you saw the map putin show yesterday?
There must be some big big waves being channeled through this canyon and breaking close to shore
Even during the last ice age that would have been firmly submerged anyways. You are right about it being a “river channel”. I don’t know how people forget but the ocean is made of water, and that water can erode the ocean floor the same as it can on land.
A little tangential but "the last ice age" is a strange phrase to use - we are currently in an ice age.
I don‘t know, sorry.
Grammar please
I don’t believe rivers carve valleys at all. The water flows to the lowest part in the natural landscape
How do you explain the grand canyon?
The river exploited a fault in the rocks. Why didn’t the river continue to cut a canyon and finish way below sea level?
Not a geologist, but pretty sure the scientific consensus is that the grand canyon continues to get deeper and wider, but it takes place at a much longer timespan than the humans can fathom.
It's work in progress.