As a resident of the Western NC area and an engineer, I really appreciate your videos. Your ability to explain these concepts in layman's terms is very helpful for people to understand this geologic event we witnessed.
Really appreciate this series of vids about Helen / Ashville area. A friend of mine's family was heavily effected by this event. Your work has really helped me understand the what and why of this life changing event.
Hi Philip I have been watching for a new video from you. The way you explain things and demonstrate is so helpful to help me understand just how things happened during Helene. It is still very horrific to take it all in. Thank you very much.
Glad it is useful. Horrible things to see, but there is a reason they happened. If you watch long enough (thousands of years or more), it would seem like a usual thing.
Excellent. How Alp-like Appalachians became hills over millions of years. How those pretty flat pastures/ coves alonside drainages came to be and cause people to want to live on the meadows. Why the Los Angeles River is a deep paved gully running through LA below the mountains. Why John McPhee observed that rounded stones at the mouth of the Platte River on the Missouri in Nebraska can be traced to their source mountain rocks in Colorado.
One of the things I've noticed about these devastating landslides, is the bigger ones start way up on a steeper and higher mountainside and bring a lot of debris, compared to smaller ones that might go over a road or something and are not as bad as landslides like Stoney Fork and other areas. I worry behind our house but it's not a steep and tall mountain, but Sugar Mountain is behind and above us with a lot of development. I know there has been a landslide next to where we live many years ago and why it worries me. I feel like I'm having a geography class every time I watch you and I thoroughly like it knowing I'm going to learn more every time. You are a great teacher and explainer!! Knowledge is everything!
Another incident that was in close proximity to the Black Mt Range. Seems like in every direction from Mt Mitchell it was significantly worse than other places, as far as slides/flows.
Dang. Nearly 1600-1700ft vertical drop in less than 1mile of distance. Wow. That is WILD I love watching these videos and marrying the information on maps on some hiking apps I use. These videos really help to make sense out of what I've been seeing over the last 2+months These videos will also provide future generations with information as a historical reference. We are all being educated for free, and should be very thankful. I know I am.
You create the most helpful videos! You explain these concepts so thoroughly and make it easy for those of us who are not experts to visualize. Your paint illustrations are clear and concise, even while showing difficult concepts. Thank you so much.
Great breakdown, as always, of some of the dynamics behind what was a very surreal day. I've always heard that streams are surface expressions of the water table. We had so much rain that day it felt like the water table was sitting 1-2 inches above ground level because that was how much flowing water was on every surface of the mountain. Until a couple hours after it stopped really raining things were very weird.
yep, about right. if the whole surface flowed, it means full saturation was reached and overland flow had begun. at that point, everything is straight runoff and floods the streams massively. it’s like the whole landscape is a parking lot at that point.
I live in a creek bottom at the base of a ridge and sheet flow like that is a regular thing after a couple inches of rain. Amazing and a little scary .
another great video. another analogy or means to visualize is if you had a scale that worked under water it could be demonstrated that a rock out of the water weighs more than the same rock submerged in water. granted, the rock won't float, but it will weigh less submerged (directly proportional to however much water it displaced). so if it weighs less there will be that much less friction holding or "binding" a group of rocks to the bedrock and at some point gravity overcomes the friction and ... whooosh ... away she goes!!!
Fantastic work. I would like to add specific gravity to the mix. People may wonder what's that? A simple example, grab a 50 lb rock and walk into the water. The deeper you get the easier it is to carry. In simple terms the pressure (weight of the water) is actually carrying part of the weight of the stone
Another very good explanation. Everyone of your vids teases out and vastly adds to knowledge I learned in my ocean engineering and oceanography studies. I really enjoy these, thank you
I just want to comment and let you know how much I enjoy your channel! Your explanations and using paint to explain geology, especially local in the Appalachian Mountains means so much to me. Helene missed my town of Murphy, but I love the entire area and it breaks my heart thinking about the folks that lost everything. I just wish this is a wake-up call to developers and if not them, to anyone considering building or buying a home near mountains such as the Appalachians. Thank you!
I used to work at a place that made a fine grained PVC plastic. Up in the bins it would pack to between hard packed snow and cement. Stick an air line in the right place to fluidize it and it would run out like water.
exactly the same process. I use glass sandblast beads to model fluidized stuff like this. you can pile up a cone of them and give a tap and it turns into a puddle of them
That was great! That ol phrase: "You learn something new every day"... thanks for making it easier to actually understand what's going on! Love these videos and I did learn something new yet again! Love these videos 🙂
Thanks for the effective visuals and explanation of debris flows. They were very useful for me personally to understand the physical events that resulted in these flows. Well done. Look forward to more great content.
Another important part is that the fine soils and dust get suspended in the water and make it even slicker. Any clay in that water will thicken it up a tad but also make it slicker than grease. If the rocks try to settle and stop, the greasy clay keeps them from having enough friction to set into a solid. Until that water dries out and the clay/soil hardens back up as a dry material things can still be unstable for a long time. I sure would not want to build on that for years if not decades as you can never be certain everything is fully stable in the subsurface. This issue is part of my issue with calling this a flood event since it is more of a landslide that flows not a water flow really. It has water as a component but is more solid than liquid.
I went to Tim Burleson’s page and seen they’ve had more flooding. The creeks are full of sediment and just a little rain now is causing flooding again. So sad.
Every time I see giant boulders in creek beds, I picture the spherical garden rock, rolling and tumbling on a thin layer of water. Those installations always catch my attention. I always ask my wife, "How you reckon that thing got there?" Seeing massive boulders so randomly dispersed throughout the Appalachians. These vids are helping to bring that all into perspective. Thank you for putting these together. I learn something new every time.
I got a few big boulder videos on this channel. I too ask how they got there...sometimes, lidar lets you see the path they carved as they slid into place!
@@Wklambert i'm glad folks have found value in them. If you google "lidar boulders" you'll likely find some blog posts I've written about some of the boulders that have obviously slid into place. it's kind of cool to see that. only once have I found one that recently rolled into place. It was quite large, and left odd gouges in the slope on its way down. It still had mud on its edges.
Seems like the science is essentially the same as “liquefaction” (S.F. Marina District during Earthquake) and “Avalanche”. A review of Mount Saint Helens debris flows would probably be similar
That's correct. Functions of the solid earth are very highly friction based, and with reduced friction and limited loss of energy to surroundings due to a carrier medium (water, trapped air, etc.) stuff moves in crazy ways.
I just saw a documentary about early warning systems at some Swiss locations that experience debris flows on a regular basis (partially due to thawing permafrost and higher rain falls). It not only triggers a siren abut also automatically closes certain roads that are in the way. Pretty cool stuff but obviously only feasible for high risk areas.
I like your videos! I just can't sit still long enough for the MSPaint drawing exercise. That area that you dragged your cursor over at 3:13 looks like it was ready to let loose at any time. And looks like it has happened before and will happen again. Thanks for all that you do on YT!
I guess you could just fast forward…yes, most of the slopes in the area have the potential to be active, and the old fan deposits at the base confirm it! no one knows how long stuff has been piling up in that fashion, but it’s likely hundreds of thousands of years. this are had plenty of debris flows, but I’m surprised there weren’t more!
Never heard it explained this way. Very interesting and helps explain the behavior coming down the hill and once it comes to rest in the valleys. It sounds like it’s more or less due to waters inability to be compressed
essentially yes. an “over-pressure” scenario. sometimes the term “undrained loading” is used, meaning the load squeezes the water and it wants to escape but can’t
I guess some folks use it to go to sleep! I wanted there to be some mention of what happens during a debris flow on TH-cam. Tried to keep it under 30, but what can you do.
In Switzerland they have an area with a regular debris flow called the illgraben. There are some pretty impressive videos on TH-cam on this debris flow, especially a channel by a guy called Pierre-Emmanuel Zufferey. Worth a watch and be impressed by boulders weighing tons floating downhill...
got to love an Illgraben video! I love watching those. It's cool to see on Google Earth. The fan is huge, and the river totally changes after Illgrabenbach enters. It reminds me of Middle Fork Jump Off in California.
@TheGeoModels I have to look that one up. I might visit the Illgraben during a holiday but sadly my holiday then also has to feature some pretty shitty weather! (And even that doesn't guarantee a debris flow)
@@merlijnwiersma7801 The Jump Off is quite similar, in terms of being an erosional "hot spot" in a landscape with high relief and weak rock. I had to work down below it a few years back and the muddy edges of debris flows had caked around all the rocks in the valley. It looked like cake batter. Odd place. I think the debris flow watching is good in the Chitral Valley in Pakistan as well, but I'm unsure of the seasonal details!
Back in the early 80's I drove my Toyota 4X4 Hi-Lux up an old muddy road and across that mountain. It took me about three hours to get to Pensacola, NC from Barnardsville 😩.
Excellent, understandable explanation! I was wondering if over time, rain water settles through the soil, then changes direction when it encounters the bedrock surface, accumulating as the bedrock funnels downward. Does this create underground streams that erode smaller particles and then leave open cavities during dry periods. I am imagining a layer with a greater volume of water (due to the filling of these cavities and the force of gravity) that typically moves faster next to the bedrock layer than at the surface. I imagine this layer as lubrication between the bedrock and the less liquefied surface layer, almost like pressurized liquid layer where a heavy snowfall liquifies enough that the snow on a sloped roof loses it's grip and slides off a roof in one big chunk. If this is true of a debris slide the leading edge not only carries the force of the liquifed debris behind it but also the less liquefied lateral material. So as the leading edge has comparative friction stability across its surface, it might hit the vertical tree trunks like a sheet of steel floating on top of the moving debris. Did you see any trees cut through the trunks, or were all the trees uprooted?
I get the impression that trees get “chopped” but also are entrained as the material they are growing in liquefies when loaded. the soils in slope areas like one here are incredibly variable, and there may be some removal of fines at depth…I really don’t know. we do see a good bit of initial sliding essentially removing soil at the bedrock boundary, so there is a zone of frictional failure there. as for what goes on between flow head and tail, it might depend on composition and distribution of particle size.
@@TheGeoModels I am wondering if there's any point to rebuilding on stilts. Is anyone surveying where it is safe to rebuild? Would stabilization measures make a difference? Are future slides predictable or preventable?
Debris fow - collateral lava, pyroclastic, and lahar flow - snow avalanche. High angle of repose, shifted geology, downland gets over run with water and soil, or lava and tuff.
plus there's so many underground water channels amidst the stone, clay and sandy soil, tree roots...water just shoots out of the mountain in a lot of places around here (Jackson County). your educational videos are great
We think that a lot of debris flows occur where saturation becomes too much due to an underground passage (a "macropore") from on old root or something like that "pipes" water into the soil in a specific area. It might explain why debris flows only occur in a few areas with a given storm despite rainfall and topography being right to cause them in many more areas.
How would you classify this event......a hundred year.....a thousand year or ten thousand year event ? Your channel is one of my favorites...Thank you !
tough to do because those are really just ways to express likelihood of occurrence…you might get another in 10 years! I suppose I have thought that I don’t really see river flooding effects like this event in the landscape, which would suggest it was bigger than anything in a long time. that said, I might not know what to look for! more on this idea in next video…
This may seem like a silly question, but my intro to geology class was many moons ago.... Do many of the larger rocks break into smaller pieces as they are flowing down hill, or is there enough liquid between them to keep them fairly intact? I mean I could see all the mica and such in the remains of silting from flooding in Cane Creek by Fairview. I know there is a lot of sand sized stuff in there when it is all held together, but does the event break rock down in a substantial way? Thanks for all the great info! It makes me want to take my retired self back to school and get that masters in geography....
stuff undoubtedly breaks down, but doesn’t have to. I guess less breaking might make a flow stay mobile since the pieces bounce off each other and don’t lose energy? I’m not sure if down in the guts of the flow the high pore pressure “pads” impacts or not. mics is interesting…I think micros soils can be poor at draining. I have no doubt that the Craigtown flows were so big because the rock and soil are so full of mica there.
Philip, thanks for highlighting the significant changes that occurred in such a short time interval because of the severe rain from Helene. Even though I'm not a geologist, (I'm a retired chemist), I did take quite a few classes in geology during my time as an undergraduate because I enjoyed the subject matter. I recall one of my professors introducing the term "punctuated equilibrium" as a way to describe the actual environmental and geological changes that occur with the passage of time as a series of very large events causing most of the change in a relatively short time interval followed by more passive and much longer time intervals with very little change occurring. Is this still a term and concept taught in geology? After watching all of your Helene videos, I think this idea of rapid change followed by much a much longer time of stasis is my biggest takeaway about the march of geologic time, it's not linear, it's like waves or pulses.
Yes, that general idea is favored. A fellow named John Hack said Appalachia was in "dynamic equilibrium," in the sense that what you describe goes on but generally speaking, the range is evolving slowly and steadily in the long term. Folks bounce back and forth between just how "hot" erosional hot spots in the landscape might be, whether or not parts of the Appalachians really change faster than each other, etc. etc. The idea of big events carrying most of the load is probably quite correct. In low flow (low energy periods), the only mass removal is by dissolved load, which is minimal in the silicate rocks of the Blue Ridge. Flood energy, which is what does the erosional and transport work, doesn't increase in a linear fashion with water level; it's more of an exponential type of thing, like earthquake energy with Richter number. In that sense. a flood that is a bit bigger than another might do 100 times more work. As I've told other folks, research geology will quickly focus in on how much material moved with this storm, which can be estimated using lidar before-after images to see how much the ground surface and stream channels changed and where.
The Bob Ross of geology is back :) Quick question: has there been any evidence of bedrock landslides being accelerated or caused by this event or these kind of events? Basically a number of smaller landslides/mudslides together causing slope toe erosion and eventually bedrock landslides after the event? Just thinking of other issues with unstable slopes we wouldn’t ordinarily associate with weather events. I assume new uphill facing scarps seen in post-Helene lidar imagery might show this assuming the bedrock in the blue ridge mountains is right. I only did geography at uni, and sadly didn’t focus as much as I should have with geology :)
this one definitely drifted in the Bob Ross direction… we have seen a few deeper seated, intact slides of weathered bedrock. I’m sure plenty of similar slides moved just a bit. I think one that developed during the storm just moved again after a few inches of rain. in short, yes, they’re out there, but they are tougher to see remotely. we have to wait for new LiDAR…
Scree fields below cliffs and bluffs are especially prone to this as they are non compacted fill that build up over time and have a lot of space to absorb water. Once they get the critical load of water to lose their smaller friction (less compaction means less friction), they are off to the races. Again any soil can slick things up but clay or fine shale dust get really slick when wet. Also slurry and the rocks and debris of a slide like this weigh a lot more than water so that is why their momentum can cause them to jump out of a curve in the waterway.
Like scree with lots of organics here...might be Pleistocene screes that were once quite barren. Indeed, the micaceous matrix soils are definitely an obstacle to restoring friction
Outstanding explanation. The LIDAR image looks like the pattern of the land is a self-consistent pile in the lower area. If you drilled down through the lower slope, would you find a layered structure that showed previous events of a similar nature?
🙏🙇♀️ great respect for all your videos help me u see stand the geographical significance and where to live I used to live in charlotte but now moved to central Florida made sure my home home was 250 ft above sea level ✅
Unrelated question if I may…I saw an aerial pic of Kuwohi the other day and it looked like it had a couple of areas of slide off to the south west of the observation tower. I tried to search for lidar images of that, but couldn’t find any images. Just thought it was neat that I feel like I’m picking up on things like that partly due to your videos!
Yes, that is neat! Plenty of instability in the Smokies. There should be lidar on the National Map. If that landscape caught a Helene-type impact, it would go wild. The accumulated "fans" of debris there (like shown in this video) are incredibly huge.
Sorry if I missed it. Did you do a video already on the landslides on the west side of Cane Creek south of Burnsville and north of Pensacola? Asking here as it relates to this video because in close proximity to one another, there were slides that look very much like these and the others that I have seen you do then just north of those were these straight down/non-meandering ones. If this does not make sense, I will send you a video that I took from the road below them for reference
so i got one called "where did Helene's dangerous landslides start, and where did they go?' that talks about Pensacola, Tooties Creek, etc. It shows quite a few up there. They were indeed quite similar to this one. Theres a group of several of them near a bend that may be close to where you're talking about. Since I wrote this, do you have that drive thru video of Pensacola? I watched that a while back and it was something else. If so, that flow you looked at is very much like these. It went straight to the river and put some monster rocks in there. It might have slowed the flow temporarily, but all the debris coming down was so liqueifed it might have just washed away. Send your video in any case; keen to see it.
i've been following all of your videos post-helene, and i will thank you again for them. i am an artist. and i must say - you are, too!! you very effectively provide drawings that are extremely easy to understand. i expect that you could do lots of interesting artwork if you decided to try it. every time you show LIDAR, it becomes so obvious to me that these processes - like the debris flows from helene - have been happening for thousands of years. it is so clear that the flatter areas in the valleys were made flat with the process of material being moved from high in the mountains, down the mountain sides, and into the valley. with helene as an example, i wonder how much more material was added to the valley areas. and i wonder, over geological time, will the valleys become ever so much "less deep" and "wider" as this process continues to happen? thanks again for introducing me to geology - it is fascinating!!! :-)
I kept thinking about soil liquefaction with some of the major quakes in Japan over the years. As the vibration of this material coming down the mountainside, I wonder if the is a method where it essentially vibrates loose the material essentially turning the whole slide into a stream!?
Not to start it, but yes, "vibrational energy" keeps it going in the sense that the grains of sand, gravel, and boulders can't reestablish connection with each other to become more solid and stable again. The energy source for the vibration is the slope itself, and the fact it can go downhill. Earthquake liquefaction is basically like my little oval diagram, though, in the sense that shifting packing of pieces of sediment does crazy stuff to pore pressure. From a few videos captured in the storm, it looks like slides may liquefy just after they start sliding, so maybe the movement and disturbance to the material is what 'joggles" the slide material and forces the pressure increase. As stuff gets run over as it goes downhill, the shock and squeezing under the weight does liquefy it in almost an earthquake style. Appreciate the comment...glad the vid conjured up some interesting thoughts and connections.
Dry long-runout slides are usually characterized as not being well explained by the potential energy of the material before the slide started. Are wet slides such as these more or less correlated to height of fall - ignoring degree of slope, friction, etc?
I would say no…some of the biggest ones in this storm were on less extreme slopes, in terms of relief. like many things in Appalachia, it seems that soil and rock type are the big controls. materials control pore pressure maintenance and dewatering, so if youve got stuff with collapsible voids that doesn’t drain well, you can get a huge, rapidly mobile flow without the crazy topography. likewise, a rowdy slope with draining materials will “freeze” flows on the slope as they dewater
Is this what you do for work? What do geologists actually do aside from studying rocks and landforms? I am a very amateur geologist that has found interest in “rocks” from traveling so I find these videos so fascinating. Devastating for those in the area, but interesting to see how they happen. Having spent a lot of time in the southern Appalachians and the region it is very easy to imagine. I feel so much for the people in those towns. I live in Sarasota, Florida and we had three devastating storms hit us this year, but still nothing like what has happened up there. Praying everyday that ya’ll get the help needed to rebuild rather than having investors coming in like they’ve done down here forcing the locals out. Question though, what are the small lines on the terrain in the LiDAR images? Are those roads, dry river beds or what?
Little lines are most likely logging roads (there are all sorts of lines to see, but the logging roads are the most prominent). Yes, this is what I do for work. I work with Appalachian Landslide Consultants out of Asheville. appalachianlandslide.com/. We do all sorts of stuff related to slope stability. I spend a lot of time mapping older landslides and trying to determine what soil conditions caused them to happen. The information ultimately gets put into hazard maps. We also do site evaluations to tell folks where to build to avoid landslide impacts.
Does the bedrock become lubricated thereby reduces friction which increases flow due to gravity? On a recent trip to Wears Valley TN staying at an elevation of approximately 2000ft, looking across the valley toward the SMNP and viewing elevations 3000-4000ft, you could see the rippling of the mountain sides. Was the rippling the effect of debris flow? I would expect if it was, it would have taken millions of years to create this topography.
it's likely bedrock controlling the landscape shape, though there are many huge accumulated slide deposits in that area near the base of slopes. yes, water does lubricate, but the lubrication (initially) is in the form of slightly "floating" the rock pieces atop the bedrock so they don't push on it as hard, reducing their friction against it. it's sort of like picking up a rock underwater...it ain't as heavy as it is on land!
sorry for a 2nd comment. is this process also able to make the soil in the valleys more fertile? the tree material that comes down and then decomposes might enrich the soil in the valley?
or another analogy: if you took a bucket of concrete and made it into a slab an inch thick, after it hardened you could set that slab on a fairly steep roof and it would stay put. but if you took a piece of low density styrofoam of same dimensions as your 1" slab of concrete, odds are it would just slide right off the roof, because there would be less weight and hence less friction holding or "binding" to the roof shingles. furthermore, if you poured that same bucket of wet concrete on that same roof, most of it would just run down or "flow" down the roof and onto the ground.
I have a more professional question about where you can get LiDAR imaging, can you get it anywhere on earth? I have something I’m interested in imaging for but it’s in Asia
How quickly, or not, does the debris supply rebuild? We talking years in areas that have had these large heavy debris flows? Are they likely to be a problem again, if things align, with heavy rain events in the short term?
Probably thousands of years. In the next video I'll show some debris flow tracks that are nearly 200 years old and still look fresh. Faint scars visible in lidar might be thousands of years, for sure. It gives the impression that these storms as we see them today are quite episodic. Presumably, though, when we talk about "these storms," we are thinking in Holocene terms. I don't think there's consensus on what Pleistocene weather patterns were like (beyond cold), and what transitioning into and out of interglacials was like. Sediment production might have been much higher during Pleistocene cold periods, so the overall chronology might lurch a bit.
So the main question is?? Why are the round river bed as in round rocks doing right up high on the hills to be rolloin down when immersed in rain fall? But why is river stone so elevated away from the river? (2nd question)
Just the way I drew it, for ease of making things communicate the void/open space idea. The rock fragments up there would be "subangular," most likely, with reasonable corners and edges. I'm just trying to sketch it out in a timely manner...I tried working it up with more corners and angles, and it makes it harder to pull it all together! The demo with the ovals is the same thing. They are idealized shapes just to make the overall pattern/process really obvious. None of the rock actually moving to start the debris flow would be that rounded. Material the debris flow picks up further down the channel would be increasingly round, though. There are a few elevated old river gravels around in Appalachia...more than a few, really. They get left behind when rivers cut deeper into the landscape. They are seldom high enough to get involved in debris flows, though. I bed they would really give way, given the shape of rocks and the clay that often surrounds them!
last week in chattanooga on lookout mountain the famous incline railway was significantly damaged in wildfire. investigators believe the fire was sparked by heat friction generated from a rockslide. you can't put news links in these comments, but the story is googleable
Most likely the farmer moved the stream over to make his farm field bigger, creating a close to 90 degree turn for the stream easy for the debris flow to bypass.
you are correct. Drop the weight of a heap of boulders on it, and it pushes back hard. It ain't got any internal strength either, so those boulders go for a ride, in nearly hovercraft style.
Yep, that's pretty much how it is in a lot of western NC! Some of them are pretty old, too...we don't actually know long one will sit around and stay "recognizable" before it totally weathers/erodes away
make more accounts and like more! Appreciate it. Trying to talk a bit more about the finer points of how stuff works. Algorithm won't like it, but I hope a few folks will hang on!
As a resident of the Western NC area and an engineer, I really appreciate your videos. Your ability to explain these concepts in layman's terms is very helpful for people to understand this geologic event we witnessed.
thank you. it is a work in progress! this one went a bit far into the technical side but I wanted to make it.
Really appreciate this series of vids about Helen / Ashville area. A friend of mine's family was heavily effected by this event. Your work has really helped me understand the what and why of this life changing event.
@@JKwakulla appreciate that very much. Trying to offer what perspective I can
I always get excited when I see a new one of your videos in my feed. Thank you for making these.
thank you
Hi Philip I have been watching for a new video from you. The way you explain things and demonstrate is so helpful to help me understand just how things happened during Helene. It is still very horrific to take it all in. Thank you very much.
Glad it is useful. Horrible things to see, but there is a reason they happened. If you watch long enough (thousands of years or more), it would seem like a usual thing.
Excellent. How Alp-like Appalachians became hills over millions of years. How those pretty flat pastures/ coves alonside drainages came to be and cause people to want to live on the meadows. Why the Los Angeles River is a deep paved gully running through LA below the mountains. Why John McPhee observed that rounded stones at the mouth of the Platte River on the Missouri in Nebraska can be traced to their source mountain rocks in Colorado.
One of the things I've noticed about these devastating landslides, is the bigger ones start way up on a steeper and higher mountainside and bring a lot of debris, compared to smaller ones that might go over a road or something and are not as bad as landslides like Stoney Fork and other areas. I worry behind our house but it's not a steep and tall mountain, but Sugar Mountain is behind and above us with a lot of development. I know there has been a landslide next to where we live many years ago and why it worries me. I feel like I'm having a geography class every time I watch you and I thoroughly like it knowing I'm going to learn more every time. You are a great teacher and explainer!! Knowledge is everything!
thank you.
I can't click on these fast enough. Thanks Philip. Much appreciation from the Burke×Avery Co line. Well done.
Another incident that was in close proximity to the Black Mt Range.
Seems like in every direction from Mt Mitchell it was significantly worse than other places, as far as slides/flows.
Technically the Craggys I believe, but still really close
Dang. Nearly 1600-1700ft vertical drop in less than 1mile of distance. Wow. That is WILD
I love watching these videos and marrying the information on maps on some hiking apps I use.
These videos really help to make sense out of what I've been seeing over the last 2+months
These videos will also provide future generations with information as a historical reference.
We are all being educated for free, and should be very thankful. I know I am.
yes, the blacks really blew up. certainly some of the most concentrated debris flows during the storm
You create the most helpful videos! You explain these concepts so thoroughly and make it easy for those of us who are not experts to visualize. Your paint illustrations are clear and concise, even while showing difficult concepts. Thank you so much.
thank you! I do my best with it.
Great breakdown, as always, of some of the dynamics behind what was a very surreal day. I've always heard that streams are surface expressions of the water table. We had so much rain that day it felt like the water table was sitting 1-2 inches above ground level because that was how much flowing water was on every surface of the mountain. Until a couple hours after it stopped really raining things were very weird.
yep, about right. if the whole surface flowed, it means full saturation was reached and overland flow had begun. at that point, everything is straight runoff and floods the streams massively. it’s like the whole landscape is a parking lot at that point.
I live in a creek bottom at the base of a ridge and sheet flow like that is a regular thing after a couple inches of rain. Amazing and a little scary .
another great video. another analogy or means to visualize is if you had a scale that worked under water it could be demonstrated that a rock out of the water weighs more than the same rock submerged in water. granted, the rock won't float, but it will weigh less submerged (directly proportional to however much water it displaced). so if it weighs less there will be that much less friction holding or "binding" a group of rocks to the bedrock and at some point gravity overcomes the friction and ... whooosh ... away she goes!!!
Glad you find the content helpful.
Fantastic work. I would like to add specific gravity to the mix. People may wonder what's that? A simple example, grab a 50 lb rock and walk into the water. The deeper you get the easier it is to carry. In simple terms the pressure (weight of the water) is actually carrying part of the weight of the stone
Another very good explanation. Everyone of your vids teases out and vastly adds to knowledge I learned in my ocean engineering and oceanography studies. I really enjoy these, thank you
glad they are worth a watch!
I just want to comment and let you know how much I enjoy your channel! Your explanations and using paint to explain geology, especially local in the Appalachian Mountains means so much to me. Helene missed my town of Murphy, but I love the entire area and it breaks my heart thinking about the folks that lost everything. I just wish this is a wake-up call to developers and if not them, to anyone considering building or buying a home near mountains such as the Appalachians. Thank you!
I will talk about Fires Creek Mountain north of Hayesville tomorrow. Not quite Murphy, but closer than Buncombe! Thanks for the kind words.
I used to work at a place that made a fine grained PVC plastic. Up in the bins it would pack to between hard packed snow and cement. Stick an air line in the right place to fluidize it and it would run out like water.
exactly the same process. I use glass sandblast beads to model fluidized stuff like this. you can pile up a cone of them and give a tap and it turns into a puddle of them
That was great! That ol phrase: "You learn something new every day"... thanks for making it easier to actually understand what's going on! Love these videos and I did learn something new yet again! Love these videos 🙂
thank you. trying to get a other vid out Friday. I don’t like Wednesday for uploads but it worked out that way this time.
@TheGeoModels looking forward to it! Upload on any day! Big smiles all around as soon I see a post!
Thanks for the effective visuals and explanation of debris flows. They were very useful for me personally to understand the physical events that resulted in these flows. Well done. Look forward to more great content.
thank you. try to follow this one with a couple more. tough to try to illustrate debris flow workings but I will give it a shot!
Another important part is that the fine soils and dust get suspended in the water and make it even slicker. Any clay in that water will thicken it up a tad but also make it slicker than grease. If the rocks try to settle and stop, the greasy clay keeps them from having enough friction to set into a solid. Until that water dries out and the clay/soil hardens back up as a dry material things can still be unstable for a long time. I sure would not want to build on that for years if not decades as you can never be certain everything is fully stable in the subsurface. This issue is part of my issue with calling this a flood event since it is more of a landslide that flows not a water flow really. It has water as a component but is more solid than liquid.
Thank you for putting this together. Your drawing was quite good, perfectly illustrating what happens when the ground is over saturated.
Thank you. It's a bit deeper in the subject than the usual drawings, but I wanted to give it a go.
I went to Tim Burleson’s page and seen they’ve had more flooding. The creeks are full of sediment and just a little rain now is causing flooding again. So sad.
interesting to hear that. there will probably be a lengthy adjustment period
Every time I see giant boulders in creek beds, I picture the spherical garden rock, rolling and tumbling on a thin layer of water. Those installations always catch my attention. I always ask my wife, "How you reckon that thing got there?" Seeing massive boulders so randomly dispersed throughout the Appalachians. These vids are helping to bring that all into perspective. Thank you for putting these together. I learn something new every time.
I got a few big boulder videos on this channel. I too ask how they got there...sometimes, lidar lets you see the path they carved as they slid into place!
@TheGeoModels Lidar is a pretty amazing tool. I will check out the other videos, also. Thanks again 😁 definitely appreciate the lessons!!
@@Wklambert i'm glad folks have found value in them. If you google "lidar boulders" you'll likely find some blog posts I've written about some of the boulders that have obviously slid into place. it's kind of cool to see that. only once have I found one that recently rolled into place. It was quite large, and left odd gouges in the slope on its way down. It still had mud on its edges.
Seems like the science is essentially the same as “liquefaction” (S.F. Marina District during Earthquake) and “Avalanche”. A review of Mount Saint Helens debris flows would probably be similar
That's correct. Functions of the solid earth are very highly friction based, and with reduced friction and limited loss of energy to surroundings due to a carrier medium (water, trapped air, etc.) stuff moves in crazy ways.
Dude! I’m hooked on these videos!
right on. tell yo friends!
I just saw a documentary about early warning systems at some Swiss locations that experience debris flows on a regular basis (partially due to thawing permafrost and higher rain falls). It not only triggers a siren abut also automatically closes certain roads that are in the way. Pretty cool stuff but obviously only feasible for high risk areas.
I like your videos! I just can't sit still long enough for the MSPaint drawing exercise.
That area that you dragged your cursor over at 3:13 looks like it was ready to let loose at any time. And looks like it has happened before and will happen again.
Thanks for all that you do on YT!
I guess you could just fast forward…yes, most of the slopes in the area have the potential to be active, and the old fan deposits at the base confirm it! no one knows how long stuff has been piling up in that fashion, but it’s likely hundreds of thousands of years. this are had plenty of debris flows, but I’m surprised there weren’t more!
Never heard it explained this way. Very interesting and helps explain the behavior coming down the hill and once it comes to rest in the valleys. It sounds like it’s more or less due to waters inability to be compressed
essentially yes. an “over-pressure” scenario. sometimes the term “undrained loading” is used, meaning the load squeezes the water and it wants to escape but can’t
Another well presented explanation of what occurred and why. Keep them coming. 👍
Thank you. Will do. This one ran long and got a bit technical. Hopefully the algorithm doesn't flush me!
That's the best explanation I have ever heard. Thank you for sharing your knowledge.
Appreciate that. Friction is important!
The combination of water, fine mineral particles, and old broken down organic material, makes for a big slip n slide.
indeed!
Plus…. Gravity
Wow, very good description of the process. I sat through this without falling asleep, well done, Thanks.👍
I guess some folks use it to go to sleep! I wanted there to be some mention of what happens during a debris flow on TH-cam. Tried to keep it under 30, but what can you do.
@@TheGeoModels I enjoyed your field study of a debris flow source. This one is a good complement to it.
In Switzerland they have an area with a regular debris flow called the illgraben. There are some pretty impressive videos on TH-cam on this debris flow, especially a channel by a guy called Pierre-Emmanuel Zufferey. Worth a watch and be impressed by boulders weighing tons floating downhill...
got to love an Illgraben video! I love watching those. It's cool to see on Google Earth. The fan is huge, and the river totally changes after Illgrabenbach enters. It reminds me of Middle Fork Jump Off in California.
@TheGeoModels I have to look that one up. I might visit the Illgraben during a holiday but sadly my holiday then also has to feature some pretty shitty weather! (And even that doesn't guarantee a debris flow)
@@merlijnwiersma7801 The Jump Off is quite similar, in terms of being an erosional "hot spot" in a landscape with high relief and weak rock. I had to work down below it a few years back and the muddy edges of debris flows had caked around all the rocks in the valley. It looked like cake batter. Odd place. I think the debris flow watching is good in the Chitral Valley in Pakistan as well, but I'm unsure of the seasonal details!
Back in the early 80's I drove my Toyota 4X4 Hi-Lux up an old muddy road and across that mountain. It took me about three hours to get to Pensacola, NC from Barnardsville 😩.
Excellent, understandable explanation!
I was wondering if over time, rain water settles through the soil, then changes direction when it encounters the bedrock surface, accumulating as the bedrock funnels downward. Does this create underground streams that erode smaller particles and then leave open cavities during dry periods. I am imagining a layer with a greater volume of water (due to the filling of these cavities and the force of gravity) that typically moves faster next to the bedrock layer than at the surface. I imagine this layer as lubrication between the bedrock and the less liquefied surface layer, almost like pressurized liquid layer where a heavy snowfall liquifies enough that the snow on a sloped roof loses it's grip and slides off a roof in one big chunk. If this is true of a debris slide the leading edge not only carries the force of the liquifed debris behind it but also the less liquefied lateral material. So as the leading edge has comparative friction stability across its surface, it might hit the vertical tree trunks like a sheet of steel floating on top of the moving debris. Did you see any trees cut through the trunks, or were all the trees uprooted?
I get the impression that trees get “chopped” but also are entrained as the material they are growing in liquefies when loaded. the soils in slope areas like one here are incredibly variable, and there may be some removal of fines at depth…I really don’t know. we do see a good bit of initial sliding essentially removing soil at the bedrock boundary, so there is a zone of frictional failure there. as for what goes on between flow head and tail, it might depend on composition and distribution of particle size.
@@TheGeoModels I am wondering if there's any point to rebuilding on stilts. Is anyone surveying where it is safe to rebuild? Would stabilization measures make a difference? Are future slides predictable or preventable?
Debris fow - collateral lava, pyroclastic, and lahar flow - snow avalanche. High angle of repose, shifted geology, downland gets over run with water and soil, or lava and tuff.
Fantastic explanation and paint expert! Thank you I love your videos. ❤
Blessings
Very educational and informative. Thank You for the excellent class lesson!
plus there's so many underground water channels amidst the stone, clay and sandy soil, tree roots...water just shoots out of the mountain in a lot of places around here (Jackson County). your educational videos are great
We think that a lot of debris flows occur where saturation becomes too much due to an underground passage (a "macropore") from on old root or something like that "pipes" water into the soil in a specific area. It might explain why debris flows only occur in a few areas with a given storm despite rainfall and topography being right to cause them in many more areas.
Excellent presentation. Thank you.
thanks for checking it out
How would you classify this event......a hundred year.....a thousand year or ten thousand year event ? Your channel is one of my favorites...Thank you !
tough to do because those are really just ways to express likelihood of occurrence…you might get another in 10 years! I suppose I have thought that I don’t really see river flooding effects like this event in the landscape, which would suggest it was bigger than anything in a long time. that said, I might not know what to look for! more on this idea in next video…
@@TheGeoModels Sweet I thought I saw a saw at least one fairly young similar landslides on this moutain.
The before picture looks like landslides are not a new event for that mountain
very true
This may seem like a silly question, but my intro to geology class was many moons ago.... Do many of the larger rocks break into smaller pieces as they are flowing down hill, or is there enough liquid between them to keep them fairly intact? I mean I could see all the mica and such in the remains of silting from flooding in Cane Creek by Fairview. I know there is a lot of sand sized stuff in there when it is all held together, but does the event break rock down in a substantial way? Thanks for all the great info! It makes me want to take my retired self back to school and get that masters in geography....
stuff undoubtedly breaks down, but doesn’t have to. I guess less breaking might make a flow stay mobile since the pieces bounce off each other and don’t lose energy? I’m not sure if down in the guts of the flow the high pore pressure “pads” impacts or not. mics is interesting…I think micros soils can be poor at draining. I have no doubt that the Craigtown flows were so big because the rock and soil are so full of mica there.
Fascinating as always.
Thanks
New @TheGeoModels video! Heck yeah!
Might try to get one on Friday too
Philip, thanks for highlighting the significant changes that occurred in such a short time interval because of the severe rain from Helene. Even though I'm not a geologist, (I'm a retired chemist), I did take quite a few classes in geology during my time as an undergraduate because I enjoyed the subject matter. I recall one of my professors introducing the term "punctuated equilibrium" as a way to describe the actual environmental and geological changes that occur with the passage of time as a series of very large events causing most of the change in a relatively short time interval followed by more passive and much longer time intervals with very little change occurring. Is this still a term and concept taught in geology? After watching all of your Helene videos, I think this idea of rapid change followed by much a much longer time of stasis is my biggest takeaway about the march of geologic time, it's not linear, it's like waves or pulses.
Yes, that general idea is favored. A fellow named John Hack said Appalachia was in "dynamic equilibrium," in the sense that what you describe goes on but generally speaking, the range is evolving slowly and steadily in the long term. Folks bounce back and forth between just how "hot" erosional hot spots in the landscape might be, whether or not parts of the Appalachians really change faster than each other, etc. etc. The idea of big events carrying most of the load is probably quite correct. In low flow (low energy periods), the only mass removal is by dissolved load, which is minimal in the silicate rocks of the Blue Ridge. Flood energy, which is what does the erosional and transport work, doesn't increase in a linear fashion with water level; it's more of an exponential type of thing, like earthquake energy with Richter number. In that sense. a flood that is a bit bigger than another might do 100 times more work. As I've told other folks, research geology will quickly focus in on how much material moved with this storm, which can be estimated using lidar before-after images to see how much the ground surface and stream channels changed and where.
Whoop! love your videos!
thank you
Look at the topo. There is a funnel at the start of the flow. This is a water corridor/dry creek chanel.
The Bob Ross of geology is back :)
Quick question: has there been any evidence of bedrock landslides being accelerated or caused by this event or these kind of events? Basically a number of smaller landslides/mudslides together causing slope toe erosion and eventually bedrock landslides after the event? Just thinking of other issues with unstable slopes we wouldn’t ordinarily associate with weather events. I assume new uphill facing scarps seen in post-Helene lidar imagery might show this assuming the bedrock in the blue ridge mountains is right. I only did geography at uni, and sadly didn’t focus as much as I should have with geology :)
this one definitely drifted in the Bob Ross direction…
we have seen a few deeper seated, intact slides of weathered bedrock. I’m sure plenty of similar slides moved just a bit. I think one that developed during the storm just moved again after a few inches of rain. in short, yes, they’re out there, but they are tougher to see remotely. we have to wait for new LiDAR…
Nature & the unpredictable, powerful & destructive events are mind blowing & terrifying at the same time. 🙏🙏🙏 For all the people affected by Helene 💔
Incredible it cut that pasture in half….my God. I look forward to your videos 😊♥️
pasture is still there; just underneath a big slug of mud rocks and trees! glad to hear you look forward to these
Hydrology effect on geology lessons. Interesting videos. Thanks for posting again.
they will continue! glad they are interesting. Friction is one of the most important words in geology that never really gets broadcast.
Scree fields below cliffs and bluffs are especially prone to this as they are non compacted fill that build up over time and have a lot of space to absorb water. Once they get the critical load of water to lose their smaller friction (less compaction means less friction), they are off to the races. Again any soil can slick things up but clay or fine shale dust get really slick when wet. Also slurry and the rocks and debris of a slide like this weigh a lot more than water so that is why their momentum can cause them to jump out of a curve in the waterway.
Like scree with lots of organics here...might be Pleistocene screes that were once quite barren. Indeed, the micaceous matrix soils are definitely an obstacle to restoring friction
another GREAT video thx sooo much !!!!
It rained so hard so fast so much, that it literally created mud slides...a geological disaster....
Around 33:27 it looks to me like how out west they check for sheer on an avalanche test for lack of a better term or terms
driving through the mountains on i75 heading to florida the day after helene was pretty crazy with the amount of water just shooting out of the cliffs
Merry Christmas Phillip 🎄🎅🏻🎄
same to you!
For comparison watch concrete guys using a concrete vibrator. Also shares features with earthquake liquifaction.
hollers are also the same in the midwest. there are alot of hollers in Illinois along the Mississippi and Illinois river valleys
I'm interested by some of the rough country in Southern Illinois. Hicks Dome is cool too.
You are a great teacher
Outstanding explanation. The LIDAR image looks like the pattern of the land is a self-consistent pile in the lower area. If you drilled down through the lower slope, would you find a layered structure that showed previous events of a similar nature?
most definitely. a trench through it would be fascinating…and a bit frightening!
I could’ve told you yes… But I have watched these videos.
🙏🙇♀️ great respect for all your videos help me u see stand the geographical significance and where to live
I used to live in charlotte but now moved to central Florida made sure my home home was 250 ft above sea level ✅
Florida has a little bit of topography here and there! They even had a big landslide in the 1940s up in the panhandle!
Unrelated question if I may…I saw an aerial pic of Kuwohi the other day and it looked like it had a couple of areas of slide off to the south west of the observation tower. I tried to search for lidar images of that, but couldn’t find any images. Just thought it was neat that I feel like I’m picking up on things like that partly due to your videos!
Yes, that is neat! Plenty of instability in the Smokies. There should be lidar on the National Map. If that landscape caught a Helene-type impact, it would go wild. The accumulated "fans" of debris there (like shown in this video) are incredibly huge.
@ it’s just a matter of time I suspect.
Sorry if I missed it. Did you do a video already on the landslides on the west side of Cane Creek south of Burnsville and north of Pensacola?
Asking here as it relates to this video because in close proximity to one another, there were slides that look very much like these and the others that I have seen you do then just north of those were these straight down/non-meandering ones.
If this does not make sense, I will send you a video that I took from the road below them for reference
so i got one called "where did Helene's dangerous landslides start, and where did they go?' that talks about Pensacola, Tooties Creek, etc. It shows quite a few up there. They were indeed quite similar to this one. Theres a group of several of them near a bend that may be close to where you're talking about.
Since I wrote this, do you have that drive thru video of Pensacola? I watched that a while back and it was something else. If so, that flow you looked at is very much like these. It went straight to the river and put some monster rocks in there. It might have slowed the flow temporarily, but all the debris coming down was so liqueifed it might have just washed away.
Send your video in any case; keen to see it.
I Love your content.
thank you. tried to keep this one shorter but it wasn’t meant to be. hope the illustrations worked out well enough!
It was very well explained. I love a longer video. Thank you.@@TheGeoModels
i've been following all of your videos post-helene, and i will thank you again for them.
i am an artist. and i must say - you are, too!! you very effectively provide drawings that are extremely easy to understand. i expect that you could do lots of interesting artwork if you decided to try it.
every time you show LIDAR, it becomes so obvious to me that these processes - like the debris flows from helene - have been happening for thousands of years. it is so clear that the flatter areas in the valleys were made flat with the process of material being moved from high in the mountains, down the mountain sides, and into the valley.
with helene as an example, i wonder how much more material was added to the valley areas. and i wonder, over geological time, will the valleys become ever so much "less deep" and "wider" as this process continues to happen?
thanks again for introducing me to geology - it is fascinating!!! :-)
I kept thinking about soil liquefaction with some of the major quakes in Japan over the years. As the vibration of this material coming down the mountainside, I wonder if the is a method where it essentially vibrates loose the material essentially turning the whole slide into a stream!?
Not to start it, but yes, "vibrational energy" keeps it going in the sense that the grains of sand, gravel, and boulders can't reestablish connection with each other to become more solid and stable again. The energy source for the vibration is the slope itself, and the fact it can go downhill. Earthquake liquefaction is basically like my little oval diagram, though, in the sense that shifting packing of pieces of sediment does crazy stuff to pore pressure. From a few videos captured in the storm, it looks like slides may liquefy just after they start sliding, so maybe the movement and disturbance to the material is what 'joggles" the slide material and forces the pressure increase. As stuff gets run over as it goes downhill, the shock and squeezing under the weight does liquefy it in almost an earthquake style. Appreciate the comment...glad the vid conjured up some interesting thoughts and connections.
Dry long-runout slides are usually characterized as not being well explained by the potential energy of the material before the slide started. Are wet slides such as these more or less correlated to height of fall - ignoring degree of slope, friction, etc?
I would say no…some of the biggest ones in this storm were on less extreme slopes, in terms of relief. like many things in Appalachia, it seems that soil and rock type are the big controls. materials control pore pressure maintenance and dewatering, so if youve got stuff with collapsible voids that doesn’t drain well, you can get a huge, rapidly mobile flow without the crazy topography. likewise, a rowdy slope with draining materials will “freeze” flows on the slope as they dewater
Is this what you do for work? What do geologists actually do aside from studying rocks and landforms? I am a very amateur geologist that has found interest in “rocks” from traveling so I find these videos so fascinating. Devastating for those in the area, but interesting to see how they happen. Having spent a lot of time in the southern Appalachians and the region it is very easy to imagine. I feel so much for the people in those towns. I live in Sarasota, Florida and we had three devastating storms hit us this year, but still nothing like what has happened up there. Praying everyday that ya’ll get the help needed to rebuild rather than having investors coming in like they’ve done down here forcing the locals out. Question though, what are the small lines on the terrain in the LiDAR images? Are those roads, dry river beds or what?
Little lines are most likely logging roads (there are all sorts of lines to see, but the logging roads are the most prominent). Yes, this is what I do for work. I work with Appalachian Landslide Consultants out of Asheville. appalachianlandslide.com/. We do all sorts of stuff related to slope stability. I spend a lot of time mapping older landslides and trying to determine what soil conditions caused them to happen. The information ultimately gets put into hazard maps. We also do site evaluations to tell folks where to build to avoid landslide impacts.
Does the roundedness of the rocks make it easier for the water to overcome the frictional strength between them?
Does the bedrock become lubricated thereby reduces friction which increases flow due to gravity? On a recent trip to Wears Valley TN staying at an elevation of approximately 2000ft, looking across the valley toward the SMNP and viewing elevations 3000-4000ft, you could see the rippling of the mountain sides. Was the rippling the effect of debris flow? I would expect if it was, it would have taken millions of years to create this topography.
it's likely bedrock controlling the landscape shape, though there are many huge accumulated slide deposits in that area near the base of slopes. yes, water does lubricate, but the lubrication (initially) is in the form of slightly "floating" the rock pieces atop the bedrock so they don't push on it as hard, reducing their friction against it. it's sort of like picking up a rock underwater...it ain't as heavy as it is on land!
Thank you
sorry for a 2nd comment. is this process also able to make the soil in the valleys more fertile? the tree material that comes down and then decomposes might enrich the soil in the valley?
I ❤ Geology. Thank you!
glad you found it worthy!
or another analogy: if you took a bucket of concrete and made it into a slab an inch thick, after it hardened you could set that slab on a fairly steep roof and it would stay put. but if you took a piece of low density styrofoam of same dimensions as your 1" slab of concrete, odds are it would just slide right off the roof, because there would be less weight and hence less friction holding or "binding" to the roof shingles. furthermore, if you poured that same bucket of wet concrete on that same roof, most of it would just run down or "flow" down the roof and onto the ground.
Flowing concrete is a good analogy
I have a more professional question about where you can get LiDAR imaging, can you get it anywhere on earth? I have something I’m interested in imaging for but it’s in Asia
another epic sesh!
I was sweating a bit after this one
How quickly, or not, does the debris supply rebuild? We talking years in areas that have had these large heavy debris flows? Are they likely to be a problem again, if things align, with heavy rain events in the short term?
Probably thousands of years. In the next video I'll show some debris flow tracks that are nearly 200 years old and still look fresh. Faint scars visible in lidar might be thousands of years, for sure. It gives the impression that these storms as we see them today are quite episodic. Presumably, though, when we talk about "these storms," we are thinking in Holocene terms. I don't think there's consensus on what Pleistocene weather patterns were like (beyond cold), and what transitioning into and out of interglacials was like. Sediment production might have been much higher during Pleistocene cold periods, so the overall chronology might lurch a bit.
@@TheGeoModels Thanks for taking the time to respond. I really appreciate it!
SUPER JOB THANK YOU
thank you for watching.
Excellent, thank you!
Thank you for pointing out hollow 😊
as in hollow vs. holler? it’s a key distinction! got to make sure we are on the same page!
So the main question is?? Why are the round river bed as in round rocks doing right up high on the hills to be rolloin down when immersed in rain fall? But why is river stone so elevated away from the river? (2nd question)
Just the way I drew it, for ease of making things communicate the void/open space idea. The rock fragments up there would be "subangular," most likely, with reasonable corners and edges. I'm just trying to sketch it out in a timely manner...I tried working it up with more corners and angles, and it makes it harder to pull it all together! The demo with the ovals is the same thing. They are idealized shapes just to make the overall pattern/process really obvious. None of the rock actually moving to start the debris flow would be that rounded. Material the debris flow picks up further down the channel would be increasingly round, though.
There are a few elevated old river gravels around in Appalachia...more than a few, really. They get left behind when rivers cut deeper into the landscape. They are seldom high enough to get involved in debris flows, though. I bed they would really give way, given the shape of rocks and the clay that often surrounds them!
Where can I get my framed Philip Prince collection?
last week in chattanooga on lookout mountain the famous incline railway was significantly damaged in wildfire. investigators believe the fire was sparked by heat friction generated from a rockslide. you can't put news links in these comments, but the story is googleable
You forgot to mention…….Gravity.
Love the videos.
I suppose you are correct…glad you like the vids
@@TheGeoModels sorry. I couldn’t help that. When my daughter was in seventh grade her answer to her science teacher was always
“ because of gravity?”.
Let me sum this up, crap flows downhill LOL. I am just kidding, LOVE your videos sir!
Most likely the farmer moved the stream over to make his farm field bigger, creating a close to 90 degree turn for the stream easy for the debris flow to bypass.
based on the LiDAR that seems quite likely
If I ever want to buy a home in the mountains, I’ll call you to show me where the dangers are! 🤣. But really…now I know
It can be done
if im not mistaken. water cant be compressed. so not to far fetched.
you are correct. Drop the weight of a heap of boulders on it, and it pushes back hard. It ain't got any internal strength either, so those boulders go for a ride, in nearly hovercraft style.
I see old slides everywhere now
Yep, that's pretty much how it is in a lot of western NC! Some of them are pretty old, too...we don't actually know long one will sit around and stay "recognizable" before it totally weathers/erodes away
Mountains ? Lava dome ( for the most part ... ? ) Slopes that's why ...
Bob Ross of MSPaint
Doing what I can! Probably need to do a full video landscape illustration. One of these days. I also need more hair.
Fascinating
it’s a crazy process
Channeling your Bob Ross.......
Honored!
that Hillside is hollow. Go to the top of the slide with a thermal camera. You should be able to find your way in.
should just be a big jumbled rock pile!
Everything that's up has to go down.
Truth.
Because its a river of rocks and mud that's why
It sounds like the mountain had a big bowel movement
I was going to mention that, but held off. yes, that's generally a decent analogy. Strangely enough, many Appalachian ridges and peaks need to go bad!
what is your Venmo address? I'd like to make a donation
mountains melt/ valleys split/ like wax next to a fire, pours down like water Micah 1:3-4
it was indeed this way
At least they're not getting lahars
Maybe because they are Rivers of Rock and Mud Geeeez!!!!
I won't argue
So proud to be like #689. 😂 Another great video.
make more accounts and like more! Appreciate it. Trying to talk a bit more about the finer points of how stuff works. Algorithm won't like it, but I hope a few folks will hang on!
Xinjan desert and the eye of Jupiter if you prefer ...