Why Don’t All Rivers Make Canyons?

[@MinuteEarth]

CORRECTION: Some of you have pointed out a mistake in the equation at 0:57. Here's the fixed version: Model: Qb x d50 ∝ Q x S Corrected terms: Qb = sediment load d50 = grain size Q = stream discharge S = stream slope

[@billybobtheslime2999]

fr yep I knew that caught it right away totally

[@Slickstaff_Stainpants]

NEEEEERD ! (but for real, i love your vids) : )

[@jeraflare4355]

humbling to know theres people correcting the math of the people im learning from

[@edwardblair4096]

What does that curly symbol that is not available on my phone mean? My guess is "proportional to", am I right?

[@guest_informant]

@@edwardblair4096 Yes. Search "proportion symbol" for instance. I've looked into this before and never found a definitive story of its origins, and its name seems to be something like "the proportion symbol".

[@7lllll]

my initial guess was that the rock has to be somehow easier for the river to carve

[@galaxydeathskrill5607]

For someone who used to have geology as a subject - it rings true to me

[@RavenFilms]

Mine too. Something very porous, easier to erode

[@user-dz3ie5me2t]

That's what I thought too, but come to think of it, rivers cannot just keep digging. Otherwise they will go under the sea level and won't flow downstream any more.

[@Minty1337]

my first thought was similar but reversed, the river itself would be better at carving due to something like sand and sediment in the water acting like a sandblaster over time, and water with rougher sediments would dig more than ones without them.

[@MinuteEarth]

To be fair, it is worth mentioning that the type of rock, as well as the local climate can and do affect a river's ability to form a canyon. But when it comes to really deep canyons, uplift is the biggest factor by far.

[@DanielMartini2]

Wow that's actually amazing, so the river simply stays put and cancels out the rising earth

[@bruce-le-smith]

it's like if you were tiny and a 3d model was printed up around you!

[@michaelrenper796]

Little fun fact. The Nile rive has a HUGE canyon, perhaps the largest on earth, up to 2.500 m deep. Except, that this canyon is filled with sediment now. The NIle canyon was created (mutliple times) when the Mediteranean (partially) dried up 6Mio years ago. Once the water came back, the canyon turned into a bay and then was being filled in. Deep drilling in the Delta North of Cairo reveals its history.

[@1TakoyakiStore]

The deepest canyon above sea level is on a section of the Yarlung Zangbo River in China. Literally Mountain peak, a 6,000m drop to the river, and 6,000m rise up to another peak on the opposite side of the river.

[@thomasrichardholtz9031]

Came here to say that; glad someone beat me to it!!

[@samthestache8]

Out of all the minute[science] videos, this one might just have the largest discrepancy between what I previously understood/assumed about the topic and the actual reality of the topic. What I'm trying to say is this is fascinating and I learned something new today. Well done!

[@wetjeans2450]

Exactly what I was thinking. My mom is an elementary teacher and Im going to show her this.

[@happynihilist2573]

The Land: "I wanna move to a higher elevation" The River: "I don't"

[@lasagnahog7695]

Well that's fascinating. I love when something makes total sense and is unintuitive.

[@Wrugoin13]

I love this channel. This is absolutely new knowledge for me that changed what I thought I already knew.

[@LeoStaley]

When I saw the title question, about 4 different explanations came to mind, most of them unsure, and all of them wrong. I loved learning this.

[@LoneHowler]

Also many rivers change where they flow many times, one big flood and theyll carve themselves a new channel. Gold prospectors are often looking for old river channels

[@MinuteEarth]

Or, in the case of Incised Meanders, some rivers that begin downcutting due to uplift can get stuck curving in particular ways and make canyons with tons of tight turns.

[@andermium]

2:57 was uncalled for actually, you aren't an existential dread inducing channel

[@MinuteEarth]

No... but that doesn't mean we don't feel it along with you

[@Preston-oe7nd]

very interesting, and I liked that quote, "it's not that rivers exactly carve canyons, its that the worlds grandest canyons were craved around their rivers", thank you for explaining!

[@HorizonOfHope]

Minor correction: as a Sim City expert, rivers and canyons are actually formed by the an omniscient mayor in the sky who uses his bulldozer tool to totally reshape the landscape on a whim.

[@RavenFilms]

A question I’ve always wondered but never got around to googling. Thank you

[@Waterplays4855]

Thx fir lettin me know!

[@MinuteEarth]

yrwlcm!

[@therealscottfeldmann3019]

This answers my nagging question. "YEARS' ago a 'science show' explained it as: the water at a higher elevation had a higher PE and therefore could do more work on the rocks. This always made no sense to me and has bothered me for decades. THANKS!!!!!

[@diracio]

Thanks for answering a question that had crossed my mind a few times. Good to also get info aviation the new podcast - looking forward! ..and I did love the reference to "taking a break from screaming into a pillow" - very funny thanks!

[@domhuckle]

Absolutely amazing! Can you do V-shaped and U-shaped valleys next?

[@felibubbletea]

1:57 Wait.. 5km deep? Thats higher than most mountains 🤯

[@MichaelfromtheGraves]

The water only drops 1.4 km (which is still a lot) so those are just mountain peaks. Not quite the flat land that we picture surrounding the US's Grand Canyon. Also, 5km is just the average depth of the Yarlung Tsangpo through one mountain range. At one point, the maximum depth is just over 6km.

[@rowandoggo]

Driving along the columbia from Spokane WA to Portland OR was always nuts

[@captainpalegg2860]

never in a million years would i have guessed that. i always pictured either a particularly powerful river or some particularly weak stone.

[@_maxgray]

The Mississippi DOES have a canyon - in Minnesota - due to eroding through sandstone. It's actually some very cool geology - there's a set of waterfalls in Minneapolis that used to progressively move upriver until humans intervened.

[@marcopohl4875]

That only gave me more questions: Why does the river maintain its slope? How does that force adjust to other factors which you would intuitivly think would have a stronger effect, such as the rock it's carved in?

[@ERWebster]

Bit of a guess here but: The higher your altitude, the less land there is, therefor in order to move towards the ocean the slope has to be steep. This means the water is moving faster, more kinetic energy and more pressure and flow on the river bottom. Then as the altitude decreases the slope will probably decrease because there is either more land horizontally per altitude change or you are at sea level already. That means slower flows and overall less kinetic energy to bash and erode rock. So as the rock shelf lifted and increased in altitude, the water had to move farther vertically in order to cover the same distance horizontally, and had enough power to erode the rock. It cuts the channel and gets low enough that the slope no longer gives it enough energy to carve rock anymore. And since the uplifting rock is slow and the flow of the river relatively constant, it would be a very gradual but constantly changing attempt to establish an equilibrium, which the river ultimately does. This is a new concept to me and a new way to look at rivers and erosion, and I love it.

[@Scevenex]

The river maintains its slope over a long time frame because of potential energy. If the water has a steeper gradient, it will move faster, and thus have the energy to erode the surface underneath. When it is a shallow gradient, it doesn't have that force anymore, and sediment suspended in the water will fall out and deposit material instead. It naturally will balance out to create that profile because that is the most "efficient" way for water to move. Too steep, and the energy goes into erosion. Too shallow, and it cant carry the sediments. The rock it is carved into doesn't have much of an effect on this process over a geological timeframe. Whether it's limestone or granite or sandstone or sand, the water will cut through relatively fast if it is moving with enough energy. It would only make a difference in an instantaneous event, like an earthquake that lifts the land up significantly and now is hitting against rock that might deflect it onto a different path, compared to say, a landslide of mud and sand which it will pool up behind against and then burst through like a broken dam. Stronger rock will better contain the river and prevent it from avulsing (changing its path) since there are less likely to be other paths around it can make or jump to in the case of a blockage. This is why rivers in areas with stronger rock tend to be straighter and meander (form those curvey bends) less, compared to open plains where you see lots of u-bends and oxford bows.

[@AiveGi]

You guys are sooo cool! So much that I tried to convince my teacher to put on your video about firestorms! (Quick fact: I successfully convinced her!)

[@DoctorX17]

Huh, and here I thought it was the difference between rivers that erode without depositing much vs. ones that deposit a lot of material from up stream

[@tristanridley1601]

It is. Just... one level higher than that. what makes a river deposit more/less? Factors that tend toward a nice smooth curve to the sea.

[@lazyboy300]

that was unexpected in a very good way. i always thought the answer was in the type of soil/rock. some are easier to carve into. very interesting

[@dahemac]

It was Nick Zentner who originally taught me this. So frïçkïn cool! Great MinuteEarth explanation of the concept!

[@Acsion42]

That "vertical profile" at 1:00 looks alot like a cycloid, or brachistochrone curve, doesn't it?

[@nathanlehman4487]

It's worth pointing out that the Nile did carve a canyon; the Mediterranean used to be much lower than it is now. I'm curious what it's slope profile looks like now, compared to what the profile looks like if you chart the bottom of the canyon it's in.

[@turun_ambartanen]

The Lane's Balance equation being written with different symbols than are explained in the line below it infuriates me to no end! S is explained. And I can guess that d50 is explained by Ds. But The equation has a Qb and a Q, and the sentence below defines Qw and Qs!! This is why I am screaming into my pillow! \s

[@Nick-hv4vp]

You seem to have used different notation in the formula for Lane's Equation than the variables you spelled out ☺️ 0:56

[@SeventeenGhost]

Tectonic plates: stop that River: ño Tectonic plates, rising the earth: STOP THAT River, not stopping: ÑO

[@MrNicoJac]

I was expecting it was irregular rainfall. As in, sometimes a drought, and then a sudden flood getting concentrated in the river and carving out a much deeper track. But no, I learned something new!

[@Xelaria]

This is the type of question I didn’t ask, but definitely did ask, but forgot about it.

[@juliandixey3997]

0:30 did he say "Hi I'm canyon, which of course sounds like canyon..." IDK I wasn't really listening...

[@nicksamek12]

I looked at the podcast, and they're all your shorts? I downloaded 'What Is a Bee' -- what a great, long, interesting, audio-centric podcast episode! Really interesting! Glad I downloaded!

[@MinuteEarth]

Thanks for listening!

[@TomsBackyardWorkshop]

It helps that is mostly sand stone.

[@HyLee98_aka_KingAyam]

This answers a lot! Thanks for this explanation MinuteEarth

[@thefierybrib]

0:56 am I missing something or the legend and the equation are completely incoherent? Qb x d50 ≈ Q x S But the legend explains what Qw, Qs, S, and Ds are...

[@Willian-zu5gh]

yeah they messed up the notation, got confused for a moment

[@noldos]

The Ruinaulta on the Anterior Rhine is a canyon that was carved "in one go" after a huge landslide blocked the river's path. About 10000 years ago, a 10km3 landslide completely closed off the valley and created a temporary lake. The river made "quick" work of the loose rubble and carved a canyon within a few milenias. The river is back on the valley level nowadays.

[@ravenbeastofancient]

There are a couple of creeks in a forest close to my home that have carved themselves like 2-4 meters into the ground. Nowhere near as impressive as the Grand Canyon, but when I was a child they seemed *so* deep

[@Ionee-q4f]

not at all what i was expecting, thats so awesome. Is this the same process that made the columbia river gorge?

[@davialmeida4442]

The river is basically going “screw you land, I’m not raising and going down to your level, or up, I guess”

[@BS-vx8dg]

I'm having trouble wrapping my mind around this. This is so counterintuitive that I'm having to fight denialism. Thanks, though.

[@johnelliottart]

I grew up next to the Grand Canyon. I had known that top of the Kaibab plateau was 8000+ feet above sea level which would make sense in order for the river to head to the ocean. But I hadn’t thought about the river staying more or less stationary. I imagined it started at the top and worked its way down. Now I wonder if the rise of the Kaibab plateau coincided with Arizona rising out of the ocean. The river just extended its journey to the ocean as more of it rose out of the ocean.

[@HildeTheOkayish]

this actually explains so much! :O i always wondered that if the grand canyon is so deep why isn't the same true for later parts. i assumed it must have been because the area of the grand canyon had different soil or something like that. but even if that was the case that would cause issues with the water level. like imagine a stream where the first half is sandstone and the second half is pure marble. then it would quickly dig a channel in the sandstone but go up again at the marble ground? that wouldn't work of course :p so it confused me a bit. but this makes way more sense! thanks :3

[@lysandroabelcher2592]

At certain point in life and internet popsci, new "groundbreaking" *(pun intended) commonly known facts are few and far between. So the awesomeness of sipping my breakfast coffee with this one, is a total celebration and a beautiful start for a day! Thanks you a bunch Minute Physics!

[@bruce-le-smith]

how cool is that! thank you. the river was like is it chill if I chill here?

[@stephenulyate1599]

A brilliant video on antecedents rivers… maybe you could do on superimposed rivers

[@Rubymeowmeow]

land: hey I'm gonna go up now, come join me river: no fuck you, I'm staying right here canyon: gasp I've been birthed

[@fox-n-done]

Perfect

[@capertillar4634]

"daddy, how are canyons made?" "so when a daddy land and a mommy river hate each other verryy much..."

[@ShimmeringSpectrum]

Another underrated canyon: Black Canyon of the Gunnison. It's one of the steepest canyons, both in terms of how quickly the water descends through it and how straight some of the canyon walls are.

[@UnitedNations4284]

AHHHHHHHH!! 2:57

[@Binyamin.Tsadik]

Could this curve relate to the principle of least time of light? The principle of least action in mechanics?

[@crimsonraen]

Huh, that's super neat! I thought the third ingredient was just going to be softer rock. So.. Theoretically, the Colorado River could be at roughly the same elevation it always has been?

[@kingkiller1451]

I had a few thoughts about how what the ground is predominately in the region (stone, gravel, sand, soil) and rainfall could affect it, but hadn't considered the ground literally rising up around the river! I felt like there was something missing with what I could up with 😂

[@jogandsp]

Ok but WHY do rivers insist on maintaining that profile? That's kind of an important piece of the puzzle that was just neglected

[@abcdqwerty3562]

0:37

[@YEs69th420]

why dont you try asking one

[@joelmulder]

Wow, this is one of these cool facts that isn’t obvious t first, but once explained, it’s so simple and obvious you wonder why you didn’t think of it.

[@nate9065]

This is actually a way more interesting answer than I was expecting

[@missnaomi613]

Cool stuff! Thank you for being a fun place to geek out!

[@turkysanwtch]

Weren't there also natural lava dams that burst over time which contributed to carving out part of the canyon? I think some parts near Moab experienced fast erosion due to this. I also vaguely recall something about glacial dams in Canada contributing to flow and carving the canyon faster at times? I have no doubt rising terrain caused it but there also may have been variable flow over time that helped contribute the canyon's formation?

[@mytube001]

Lava fills up, it doesn't erode. But it's true that sudden glacial lakes emptying can cause rapid and extreme erosion of existing canyons and channels. But they will mainly broaden, not deepen, as the water needs to flow out, and can't flow uphill. In the US, there are large areas carved by glacial floods in Montana, Idaho and Washington.

[@turkysanwtch]

@mytube001 Volcanic dams are natural dams, I'm not saying lava eroded anything.

[@tiffanymarie9750]

A much cooler reason than I was expecting tbh

[@DeannaGilbert616]

Is that slope an example of the path of least action?

[@Shymenyou]

man, it is a bit of late night 420 friendly content, but damm i like what i learned here

[@beefybuttery8381]

Oh wow i remember asking this in the visitors center at grand canyon national park as a kid. And the ranger answered me. But i forgot the answer and also the question until right now. Like i forgot i even wondered this.

[@iambicpentakill971]

That's really interesting, thank you!

[@jeffdege4786]

Anyone from Minneapolis will tell you that Mississippi has a gorge. It even has a waterfall.

[@Merennulli]

I was always told it was due to the specific slope and the type of rock it was cutting through. Instead, the Earth is just bunching up the carpet while rivers step on part of it.

[@NyanSox]

tectonic plates are awesome

[@ObviousandIncredible]

Live and learn! I knew about it, but nevertheless it was very interesting💯

[@d3j4v00]

I lived in the grand canyon national park for almost 5 years and never knew this.

[@Wonderhoy-er]

XD I was JUST watching minute food and I got this notification 😂 This seems like an interesting watch, I'll watch it!

[@p...p]

Wow, I never looked at it like that!

[@lars3509]

In the Ruhr valley in germany, due to the centuries of coal mining, the ground sagged dozens of meters. But the Emscher river that floats through it, did not. It got diked in the late 19th century and still to this day it has the same height as back then. Though the dike had do be build higher and higher, as the ground kept sinking.

[@one_logic]

yes, why only some rivers make canyons has been a question i’ve been seeking an answer for my entire life.

[@cheezeberga]

Short, sweet, to the point. Have a like

[@vichofernandez1453]

what a great question

[@jmodified]

I suppose if a river was suddenly diverted due to shifting ground after an earthquake or landslide, a canyon could also form on the new path if there was no possibility of the water finding that ideal slope profile by any other path.

[@KnowArt]

now THAT's a cool fact

[@emctwoo]

The answer was so much cooler than I guessed. I honestly almost didnt click because I thought I already understood it

[@Robot_Overlord]

Great video

[@Homer-OJ-Simpson]

Wow, this is the exact opposite of what I had thought! Turns out the canyon grew around the river and not that the river carved into the canyon

[@sattelyte5316]

damn, that's nuts. thank you

[@YTBKd]

I was about to skip the video thinking it must be due to softer rocks. Glad I didn’t. Not a bad idea to use the tactics used by other clickbait creators to add “Not soft rocks” in the thumbnail. That might help capture some viewers who may skip. 😊

[@Chefofzejungle]

you guys are posting really fast these days

[@michaelbelonio3342]

Practical Engineering explained this about river erosion and its variability.

[@sereminar4]

This is so cool

[@kenneth69]

Because one is following the path available to it through mountains that were electrically etched from the ground up, and the others are too, but they didn't get the same experience.

[@mistermister2291]

This is totally unrealated, but you guys should have just heard my neck pop, it was phenomenal

[@TilekMamutov]

Mind blown!!

[@DrakiniteOfficial]

Damn, Water don't give a SHEET. Water be like "Try all you might, I WILL maintain my shape."

[@jesseclark7966]

So if instead the land was falling, would the river deposit sediment until it was higher that its surroundings, then change course, then do it again, leading to a river that constantly moves?

[@1TakoyakiStore]

The only river I'm aware of that breaks this rule is the Gunnison River. The slope of the river is weird, the rock it's cutting into is weird. And its age is weird. Basically it's steeper than the landscape it's in. And iirc it's because the river was on a softer sedimentary rock layer in the past that had a steep slope, but by the time that softer rock had entirely eroded away the river was now trapped in that slope already cutting into metamorphic rock.

[@M3ladi]

the information for the river slope curve at 0:57 does not match the required information for the equation

[@nitehawk86]

Hi Canyon, seems fitting you are the one to make this video.

[@grapy83]

But i don't get it still. Rivers do still carve out earth from their paths, no? so if they kept on carving, even if very slow later on, there should be a canyon in million years, even if not a grand one!

[@jmodified]

What the video seems to be saying is that when that ideal slope profile is achieved, that doesn't happen as the deposited and eroded sediments are balanced. When the land is not rising or falling quickly, rivers will find/achieve that profile without forming a canyon. Still, sediment moves toward the mouth and it has to come from somewhere, but I guess it just sort of flows in more-or-less evenly from the surrounding land once a valley is formed.

[@grapy83]

@jmodified Ah Yes! That process achieves an equilibrium. Understood 😁

[@grapy83]

@@jmodified thanks

[@Pfhorrest]

I was going to ask, wouldn't a sufficiently large bump in the initial path of descent just get carved through by the river to make an impressive canyon there too, but I wasn't thinking three-dimensionally: the river doesn't only have the options to go over or else through obstructions, it can also go *around* them, so if there was a large bump in the path of a river, the river just wouldn't flow where that bump was, but somewhere else instead. The bump has to slowly rise up around where the river's already flowing to get carved away into a canyon. It does strike me that if you had a ridge completely encircling a river, it couldn't go around, and would back up behind the ridge into a lake, until it found the lowest path over the ridge and then started flowing out that way. Which I imagine would in fact carve an impressive canyon there eventually, no?

[@İzmir_city_state_republic]

Just learned it this friday by geography teacher, same thing. Different languages

[@SamButler22]

So when The Flintstones went to the Grand Canyon and it was like an inch deep; that's exaggerated and silly, but not that crazy?

[@akira6457]

So canyon is just earth wanting to rise but river is like:nuh uh, i'm keeping my slope

[@michaelcurley7002]

Very cool