When Did Plate Tectonics Begin on Earth? (New Paper Alert!) GEO GIRL

[@WalterHildahl]

My Dad work for NOAA in the 60's .And I remember him showing us kids the pictures of the sonar images of the Pacific mid-ocean ridges, Proof that the sea floors spread and then looking at the map of the Atlantic Ocean. And you could just see how the continents once fit together. It blew my 6 year old mind.

[@treelight1707]

I remember that feeling the first time I saw it.

[@tygical]

​@@treelight1707 same here

[@Astroponicist]

Now go look at the Pacific Ocean, the shape of the coastlines of the continents on the east and west of the Pacific Ocean, & the Patagotitan mayorum dinosaur.

[@wyvvernstone]

Lucky you. I get to hang out with creationists who don't understand basic puzzles...

[@stevenbaumann8692]

That is cool.

[@texcatlipocajunior144]

Gotta love minds that can conceive such colossal processes over time from astronomy and the fossil record we are left with today. You never disappoint me with the new ideas you throw out against the walls of my mind! Some of them slide off due to my ongoing mental fossilization but at least they slow the process down. Thank you again.

[@ericclayton6287]

Well done! Thanks for the link to the paper. I know enough to know I know very little. It strikes me as the mantle crustal boundary becomes deeper and as crust thickens and becomes more brittle the plume and drip model would stop working. There are large cold plates tomographically posited at the core mantle boundary changing convection patterns and heat exchange. Sigloch and Fuston are working on that. We can only guess at this point but the work done in the last twenty years is literally ground breaking.( pun intended)

[@donaldbrizzolara7720]

Fascinating! Our knowledge of the earth’s history has come so far. I remember my first geology class at UC Berkeley in 1964 our professor telling us about a radical new theory called plate tectonics. We all thought “No way…how can that be?”. Excellent presentation Rachel. Definitely food for thought.

[@GEOGIRL]

That is so crazy to think! How far we have come 😊

[@ahamillphotography]

My goodness! What was your reaction at the time? And what was your journey like towards accepting the plate tectonics theory? I'd love to hear more of your story!

[@malcolmmarzo2461]

Yes, I too remembering being in a geology class in 1966 where a professor was talking about a new theory called "Continental Drift." Then a dubious hypothesis among the "science is settled" consensus : -)

[@barbaradurfee645]

Hi Don, as a fellow dinosaur I too remember the “this is a developing idea” era of plate tectonics.

[@michaelmckeag960]

As a (nerdy) high school student in the early 1960s I attended a meeting of the American Geophysical Union, not realizing I was witnessing a pivotal moment in earth science. Actually, two moments, I also recall closeup images of the lunar surface displayed at the meeting, transmitted from a space probe just before crashing into the moon. Soft landings came a few years later, with humans on board who returned with samples; another pivotal moment in earth science.

[@squidnoid8]

Very well done ! That’s a whole lotta geology crammed into 20 minutes. Time well spent ! Thanks for posting.

[@stevenbaumann8692]

She is so much more focused than I am. I tend to ramble.

[@garycameron8167]

Your video - specifically the diagrams you show of Drip Tectonics - now makes sense of several samples of gneiss I collected from the Black River, just south of the Hatfield dam in Wisconsin, this past summer. This small area has a huge variety of gneisses and some granites, all from the Archean. The specific outcrop I was collecting on has been reliably dated to 2.815 GY and has some very odd gneisses indeed that I could not quite understand until now. Two of the samples I collected were clearly gneisses, but with a difference. When looked at from one angle you can see very nice (not-gneiss?) rounded crystals, but rotated 90 degrees you see the classic gneissic banding - almost like fibers in a piece of wood! After seeing this structure, I wondered if the original rock had been stretched. Up till now, I had always been under the impression that gneiss was formed by compression in continental crust, as is commonly shown in diagrams. The diagram you show of Drip Tectonics now answers this puzzle as it shows gneisses being formed by stretching of the lithosphere between the descending Drip greenstone belts. From now on, perhaps we should divide gneisses into Drip Tectonic (extensional metamorphic) and Plate Tectonic (compressional metamorphic) types? Thoughts?

[@madcow3417]

I would love to play with a model of lid tectonics. I'm picturing something like a lava lamp, but it would probably require different materials or more extreme temperature changes across heights.

[@Broken_robot1986]

Please make it a novelty gift that I can buy at the mall.

[@stevenbaumann8692]

I am actually working on such a physical model. Once I get these papers out.

[@wrekced]

​@@stevenbaumann8692 A physical model will need some active heating and cooling in different zones. That is an interesting design challenge... if you take the lavalamp idea and make it in a small fishtank. There are videos about making lava lamps... with the right set of temperatures in the tank, you could probably make it simulate any one of the tectonic regimes. Cover the top and bottom with a combination of heatsinks and peltier devices with enough thermal capacity to remove or add the right amounts of heat to make the desired regime occur. Not an efficient setup, but I think it would be easily controlled by an sbc running a python script. A settup like that would be good enough for a proof of concept demonstration. After that, you will have a better idea of how to achieve the results you want to see. You could even try making it with enough area to simulate a mixed regime of lid and plate tectonics after you get it working on a smaller scale. You could get temperature feedback with a set of very tiny thermisters in a collumnar array at precise spacing, say every 1/2 cm. It could be controlled by an mcu (or two) with a ton of adc's that could feed the data to the sbc. If you 3d print holders for the thermisters, you can get fairly precise spacing and they could be streamlined so they interfere as little as possible with the flow of fluid around them. If you really want to get fancy, you could incorporate some esp32cam's in sealed enclosures inside and outside the tank to get still, timelapse and video data. I'd really like to see a video of such a system working. Its an interesting idea, but I don't have the time to do it myself. I would love to converse in email with you about designing and making it if you want my two cents.

[@matthew3136]

Lava lamps will never not be cool.

[@charlesjmouse]

Lovely! You're always worth watching. I wonder... Ignoring our likely long term trend toward 'stagnant lid' for the moment, I wonder if Earth cycles between relative 'squishy lid' and 'plate tectonics' at least in part driven by the formation and breakup of super continents? ie: The first super continent formed at the end of our first bout of (partial) plate tectonics, and a future last super continent will form on the transition from plate tectonics to stagnant lid. Meanwhile... ...on top of the trend from squishy, through plate, to stagnant, we have: -Plate tectonics (to an increasing degree over deeper time) moving blocks of continental crust about -Until that process gets jammed-up by said continents / cratons collecting in a single block -For a while we have a transition back to (full to partial) 'squishy lid' depending how far along the cooling trend we are -Until insulated by the block of super continent above an induced mantle plume beneath cracks it apart -Kicking off another bout of (relatively greater with time) plate tectonics Over time cooling of the Earth makes 'squishy plate' less widespread during that phase of this cycle to the point 'stagnant lid' dominates and the whole cycle ends with a last supercontinent that can't be split apart... ...at that point the last induced mantle plume may peter out, leaving us with an essentially dead world, or maybe there will be a last hurrah with an Olympus Mons-like volcano. PS: I suppose what I'm really saying is once you have cratons it's the oceanic crust that is cycling between 'squishy' and 'plate' behavior, but there will be precious little evidence for that as oceanic plates don't last very long... once we are on a plate tectonic phase. Another long ramble. I guess any proper geologists who got this far can comment on how sensible (or not!) I've been.

[@takaela]

also a non-geologist, but this was my first "common-sense" thought, too... it would be interesting to see the timelines of the two phenomena overlapping?

[@Dragrath1]

The formation of a supercontinent seems likely to be responsible for stopping the first wave of tectonics the latter waves of plate tectonics as we know it is probably more complicated the two processes which seem particularly relevant are in no particular order. 1) The temperature induced stability regime of various hydrous mineral phases less dense than the average anhydrate minerals(without water) in the upper mantle. These minerals are more stable at lower temperatures and thus they require the cooling of the mantle to a critical temperature regime. According to a paper from 2019 there simple temperature cooling curve suggested this threshold should have been reached around 1 billion years ago allowing pockets of mantle enriched in water derived from subducted lithosphere to begin to ascend under neutral buoyancy. The oldest Flood basalt with this particular chemistry that I'm aware of was the Franklin Large Igneous Province associated with the break up of the supercontinent Rodinia which is as far as I can tell the first dramatic supercontinent break up as opposed to supercontinent rearrangements and failed rifts during the Mesoproterozoic. 2)Because of some isotopic bias in the formation of felsic minerals beyond my understanding you can apparently measure the isotopic ratios of Titanium 49 and Titanium 47 to study the degree of how well mixed the material in a given melt is compared to undifferentiated chondrite meteorites. From this work scientists have determined that the upper mantle seems to have become well mixed by 3 billion years ago. The curious thing however is that hot spot associated Ocean Island Basalts sourced from the lower mantle have quite variable isotopic ratios all of which are more enriched in the depleted Titanium isotope ranging from having ratios which look like chondrites indicating that the material has effectively been isolated from the surrounding mantle in the past 4.5 billion years to more intermediate values suggesting they have been mixing for some time. This coupled with Helium 3 gas emission from these hot spot volcanoes an isotope of Helium which is expected to have been lost during planetary differentiation since Earth lacks the gravitational pull to hold onto a helium gas envelope and it seems clear that the lower mantle is largely primordial material which has never been fully differentiated and is still in the process of mixing. The paper's average estimate for when this mixing of the lower and upper mantle begun suggests it started no earlier than approximately 2.7 billion years ago which is suspiciously close to the timescale for the start of this first stage of plate tectonics. I suspect this is the true nature of the engine of plate tectonics powered by thermal and gravitational potential energy via convection between the upper and lower mantle.

[@mosquitobight]

The Wikipedia article on Venus says that planet is in a form of "stagnant lid" with long periods of no tectonics, punctuated by a rapid subduction and reworking of the entire crust in a short time. Hopefully Earth won't be heading into that extreme. I suppose the presence of a water ocean largely makes the difference.

[@Dragrath1]

@@mosquitobight That hypothesis of Venusian tectonics has based on my read of the literature and online lectures/interviews with experts on the subject been largely debunked. It comes from the cold war space race and he preliminary study of the Magellan mission mapping out the world at fairly low resolution and coming from a time where plate tectonics was still in its early stages of development as an accepted theory back on Earth. Subsequent work both new and reanalysis of those early results in a more well developed tectonic framework show a more dynamic albeit still quite alien landscape. Of particular note is that the aapparently "featureless" landscape commented on that lead to that hypothesis has been shown to contain regions which look to be bordered with small scale transpressional and transtensional boundaries, an area which looks like it may be undergoing some form of dynamic downwelling/quasi subduction process as well as at least one major caldera forming eruption having been identified within that mission's zones of overlap between its survey mapping project. Keep in mind that the data in question is at a size scale where the smallest features you can resolve through the clouds are comparable to the size of say California meaning that the small features in question are actually quite large just small compared to Earth's plates.

[@FollowingGhost]

I'm old enough to remember teachers saying we didn't know why the land masses looked as if they fit together. They also taught that sauropod dinosaurs could only live in water because they couldn't support their weight on land. Even then, I could see that the continents weren't a random pattern. At my age now, I'm still amazed that teachers simply repeated information when it was visually incorrect. Rather than ask why they just followed dogma. I've enjoyed your presentation of how these processes function even though I can't get out and study the way I did.

[@mjinba07]

Lol, I recall my teacher actively dismissing my young observation. She did NOT want class discussion on the matter. Now after retiring from decades of public service myself, I think she was probably just tired, focused on her lesson plan, and thinking about kicking her shoes off and having that scotch & soda at the end of her day.

[@gunnargronvall9385]

As a geologist this tectonic history of Earth is very interesting . I am a new subscriber. My hobby is Astronomy .

[@patrickfle9172]

Oscillating between convective cooling (plate tectonics) and an insulating lithosphere (stagnant lid) makes sense, indeed. Thanks for the inspiration 👍🏻

[@erkinalp]

that's similar to venus' repavement tectonics, which is a periodic alternation between lid and drip tectonics

[@gaufrid1956]

Sitting here in Cagayan de Oro City Mindanao Philippines, the subduction of the Phillipine Sea Plate under the Eurasian Plate provides fairly regular earthquake activity. It's amazing that geologists can look back at what happened in the distant past, based upon the evidence in the rocks.

[@joecanales9631]

Hi Rachel, thanks. Tectonics has always been important in my career (not so much now as a greenhouse operator, but always a fascinating topic). Having been actively involved in fossil fuel exploitation, speculation of tectonics before Phanerozoic wasn’t as important, but my interest in the Proterozoic has grown since retirement (way more interesting!). Thanks for the links to the article, but looks like I might have to join GSA or pay for the article. Dr. Stern’s previous articles look free though. (Interestingly, articles from the European Geological Society are available without a paywall,{although it might just be the ones I’ve looked into}). Damn, I’m getting long winded. 1: seems water is more common in other planets. 2: life may be common, maybe complexity requires complexity in tectonics? 3: maybe eventually life on Earth will evolve into intelligence before we extinct ourselves. Thanks for your videos which help keep me up to date on topics of interest!

[@joecanales9631]

Oops, that’s EGU, European Geosciences Union.

[@DavidSmith-jj7ll]

Oh man, blast from the past. Bob was at the department when I was working on my degree at UTD. Hi Bob! Nice to see that the guys are still doing good work!

[@LeeJamison100]

An interesting thought in this video is the reference to drip tectonics on Venus. This is especially interesting in light of the apparent repaving of the surface of that planet in the last 250,000,000 I've seen referenced in work from NASA planetary scientists, probably including Stern. This brings to mind the possibility planets like Earth and Venus could have experienced something like episodes of relative stasis, interrupted by what pre- tectonic-aware geophysicists used to call "orogenic storms" in which an area of 'drip' could drag down whole regions of crust, simultaneously stirring up circulation and upwellings from below. This might then incite similar drip-and-drag cycles on surrounding crustal regions. Presumably, such episodes of stasis and storm could trend rarer as the planets cooled, and the size of crustal/lithal regions would also grow larger and move more stably. Fantastic video!

[@dirk-hennerlankenau4899]

This again is a most informative and excellent video. Thank you very much, indeed !! Cheers, Dirk

[@StefanBurns]

Drip tectonics makes perfect sense considering the amount of planetesimal impacts Earth sustained in its early history. Large scale magnetic anomalies show evidence of this. The strong impact and then sinking of metallic material would initiate convection and perhaps could have been a dominate factor in starting plate tectonics as we know it

[@treelight1707]

These were exactly my thoughts. And why Earth didn't get Venus' fate.

[@sundancebilson-thompson414]

l@treelight1707 I don't follow your logic there. Surely there would have been impacts on Venus as well as Earth, which by this argument would have initiated plate tectonics, so how are you explaining the habitability of Earth vs the inhospitable conditions on Venus?

[@treelight1707]

@@sundancebilson-thompson414 We don't know for a fact that Venus had the same amount of bombardment as Earth did. There's a difference in size (considering the Moon), and the orbit (also considering tidal forces here). That said, it is still a valid point to look into.

[@sundancebilson-thompson414]

@@treelight1707 Thanks for the reply. I'm not saying you're wrong, and I get the differences you mentioned, but if anything they seem to make impacts on Venus more significant, not less. My first thought is that the presence of the Moon shields Earth from impacts (especially as the further we go back in time, the closer the Moon was to Earth, and so it blocked Earth from incoming objects across a larger region of the sky). Also, any body on an elliptical orbit around the Sun will be moving faster as it crosses Venus' orbit than Earth's, so would hit Venus with more kinetic energy. There may be other factors which offset those points and make impacts more significant on Earth, so a proper quantitative analysis world be interesting to see.

[@pufthemajicdragon]

I'm definitely not a geologist, and my understanding of plate tectonics is what I learned in middle school, so this is a totally uneducated comment. But me trying to understand *how* a planet could transition between "lid" and "plate" tectonic activity has me thinking about what a "post-plate lid tectonic" might look like. And I think calling it a "single lid" is probably inaccurate. My intuition tells me that once the crust breaks into plates, they couldn't easily meld themselves back together into a single lid. For my brain to wrap itself around this idea, I envision the transition being more like a move between "low activity" plate tectonics and "high activity" plate tectonics. During the "low activity" periods, plate spreading would be extremely slow or maybe stop entirely, but you would still have those plate boundaries. Instead, as plates get larger, you would see more "lid-like" tectonic activity towards the centers of those plates, reducing the mantle pressure that drives ridge expansion and thus leading to "stagnant" plate movement. I'm also trying to imagine what "lid" tectonic activity looks like, and if I had to guess I'd say features like Yellowstone would be examples of lid tectonics where Hawaii and Japan are examples of plate tectonics. I'm not sure it's possible to have exclusively plate tectonics, just squishy lid tectonics with some plate activity thrown in the mix as part of the transition from squishy to sluggish lid. I also think it would be rather difficult to find evidence of plate tectonics near the centers of large plates. Lid activity would necessarily dominate in the geologic record in those places because plate tectonics would have so little direct affect far away from a plate boundary. And any evidence for lid activity closer to plate boundaries would necessarily be muddied by the plate tectonic activity. Well, I *did* pay attention in middle school science class... Let me know if any of this makes sense or if I should read a few geology papers before commenting next time :D

[@ahamillphotography]

Great video. I'll definitely check the paper out. One thing strikes me - if there was that second, longer period of lid tectonics, I'm presuming, as slab pull would no longer be in operation, lateral movement of the lithosphere would have stopped. Obviously we don't have any oceanic crust from that time period, but what about the geomagnetic data locked into portions of continental crust? Is ther a presence of evidence that the lithosphere was not moving then?

[@Dragrath1]

It only makes sense that it isn't neat in tectonic regimes particularly as seismic tomographic surveys are revealing the more nuanced and complex internal structure of modern Earth. There was several interesting papers in the conversation which I came across earlier this year which might be relevant. The first was one was looking at how titanium isotope ratios of primitive lavas have changed over geologic time with a known bias in the reactivity between the two isotopes being associated with the formation of felsic minerals allowing the amount of Ti 49 relative to Ti 47 of magmas which arise due to biases in the formation of felsic minerals letting scientists gauge how well mixed the mantle has been over time. One of the major implications of this kind of work is that while Earth's upper mantle appears to have become isotopically depleted in the heavier isotope of Titanium and stabilizing at that level indicating a well mixed upper layers Ocean Island Basalts derived from deep upwelling associated hot spot plume material show a more variable isotope mixing ratio ranging from chondritic isotope ratios to only slightly less depleted than the upper mantle for the two isotopes of Titanium than Earth's upper mantle which indicates that the mixing of material from Earth's lower mantle is a geologically recent and ongoing and thus likely transient process. Another paper which caught my eye was related to the discovery of a vast slab wall curtain descending into the lower mantle right beneath the East Pacific Rise. This curtain using the steady sinking rate hypothesis gives a fairly interesting timing with the appearance of two Oceanic flood basalt provinces during the Cretaceous specifically the Caribbean Large Igneous Province and the Ontong Java Plateau which both formed contemporaneously with a dominant major pulse around 116 Ma and a smaller bit still flood basalt scale pulse around 90 Ma. The earlier of these times seems to fit with the general timescale of when this vast ancient slab wall seems to have finally piled up enough settling crustal material at the Mantle Transition Zone to being to descend into the lower mantle and the more exposed and well sampled of these oceanic plateaus due to its accretion onto the South American continent, the Caribbean large Igneous Province is the only known occurrence of Komatiite lavas since a brief window in the the Paleoproterozoic the Winnipegosis komatiite belt ~1.8 Ga which I can't help but notice it could potentially be lining up with the timing of this earlier proposed Paleozoic plate tectonic regime if the screenshots of the figures from your video are anything to go by, since the paper is paywalled making it inaccessible to anyone not independently wealthy or currently linked to a university with an active subscription. The mechanism proposed for both Cretaceous LIP's where Phanerozoic Komatiites are present involves the squeezing out of lower mantle material into the upper mantle to feed what are the largest know flood basalt provinces in the World (the Ontong Java plateau) and the youngest Komatiites in the world. Putting these together it suggests the events of the Cretaceous which also align with the two intra-Cretaceous mass extinction episodes and the mantle hot spots within the Pacific also seem to have some of the most primordial isotope ratios of Ocean Island Basalts suggesting we may be looking at a younger but comparable process to what likely occurred during the Proterozoic eon to possibly initiate plate tectonics. Its mostly speculation but the correlations are fascinating and call for further study IMO. I wish I could read this paper. :(

[@sundancebilson-thompson414]

I always find your videos fascinating, and this one is no exception. Something that intrigues me is how (if) CO2 would cycle between the atmosphere and the lithosphere in a squishy lid scenario, compared to a plate tectonic scenario. Would the world have gone through greenhouse stages if surface rocks were saturated with carbon and didn't subduct? And then the climate cooled once plate tectonics started again? If it possible that something like this happened in Venus, but given its proximity to the Sun, the squishy lid caused a runaway greenhouse effect that resulted in Venus losing its liquid water, and that in turn made plate tectonics impossible?

[@Weirdoid]

I always wondered if the impact that formed the moon helped create our current tectonics. After all it is tough for me to picture a planetary impact not shaking things up and breaking things.

[@maushardt13]

Very cool, I've been interested in plate techtonics since I was 8 years old, and this video was the most concise way to put together too. Love your work, good brain food 😋♥️

[@georgefspicka5483]

Hi Rachael ... an absolutely fantastic talk. As I say, I always learn new material when watching your presentations. I'll be giving my own hour-long talk at the NHSM in March, "Extinction and Other Fun Facts." And as I'm sure you've surmised, the "BIG 5"is only part of the festivities 😄

[@danwylie-sears1134]

It's nice to see "eclogitized delaminated diapirs" too, instead of only "drips".

[@TerryGloer]

Happy New Year, GEO GIRL! 🎉

[@pierremainstone-mitchell8290]

Wow! A fascinating video! The most interesting thing for me was the possibility that the rarity of plate tectonics might be contributing to the rarity of intelligent life!

[@punditgi]

Geo Girl opens my eyes to enlightenment. ❤🎉😊

[@jubilee3180]

The collision that gave us the Moon cracked up our crust, liquifing most of it. the remaining smaller pieces of the original proto crust that survived the collision became the first continents, given the kinetic energy to drift around and collide by the force of the collision impact event. Without that early planetary collision event, we'd be like Venus, no moon, solid crust, no moving plates. I'm just a humble earth science teacher, but this is my contribution to the field. Not sure why no one has made this connection before.

[@GHOST-hd4wm]

This constitutes a prohibited history that parallels a cyclical phenomenon occurring approximately every three thousand six hundred years, during which the Earth's crust shifts in response to the powerful magnetic influence of a forbidden planet within our solar system. This planet's trajectory intersects with the Earth's orbit around the sun during this period. Do you understand?

[@GHOST-hd4wm]

My previous comment was hidden by KZbin because it is forbidden to talk about the moon's origins.

[@GHOST-hd4wm]

Our moon actually belongs to another planet in our solar system which intersects the Earth's orbit around the sun approximately every three and a half millennia.

[@dragonfly.effect]

Two questions: (a) How does this lid/plate alternation fit with the proposed supercontinent cycle(s)? (b) Is the continental vs oceanic crust dichotomy necessary for plate tectonics? E.g., the seafloor subduction introduces the water into the process. How important is that geologically? (You may have to find a metaphor involving something like a two-layer eggshell. 🤔)

[@Georgewilliamherbert]

Immediately what I thought of watching and listening. Checking the paper out next.

[@brentwilbur]

Given this information, I can see how, early in Earth's life as a planet, centrifugal force would create a persistent equatorial upwell of molten material. Plastic landmasses would then flow simultaneously north and south toward the poles where they would drip and sink back into the mantle. So, instead of localized, hotspot-driven convection, this would be a global material recycling. Just imagine titanic gyres visible from space at the poles, whirlpools of rock.

[@AnnoyingNewsletters]

13:10 Liquid water being stable at the surface of any planetary body is a unique thing that we do not *_sea_* very often... 😅

[@xelaxander]

What factors contribute to plate tectonics vs lid tectonics? The video hinted at temperature, but absent additional factors that should be monotonically decreasing, not allowing for switching back and forth. Edit: A video on the foundations of tectonics would be great. Why do plate tectonics appear and why we currently don't have lid tectonics.

[@ronaldbucchino1086]

Very interesting -- I love it. Things were getting to predicable -- now lots of space for future PhD candidates to do more work!!!

[@barbaradurfee645]

Excellent graphics to help get the ideas across, so happy to get a new video, thanks Rachel!

[@elvwood]

Really interesting, thanks! I'm not sure if I should admit that it set my ex-game-programmer mind going on how it could be used to generate "realistic" random planetary maps...

[@Julian_Wang-pai]

Natural sense - static is an unusual state. Oscillatory change is much more typical. Excellently clear explanation GG 🙂

[@joanfregapane8683]

What a fascinating discussion! The past leading to the far future in our planet’s tectonic history.

[@robinredbeard]

Thank you!

[@iviewthetube]

Great points. Liquid water on the surface does seem to be why we have plate tectonics on Earth. Do you think that impacts may play a role in those transition periods you mentioned and in part why the mantle remains hot? Judging by the number of craters on Mars and the Moon, Earth has been impacted a lot.

[@benmcreynolds8581]

Could i compare the crust and the lithosphere to a giant millipede moving around? It's obviously an analogy. Also i think it's fascinating that so much of our water, has emerged as steam after being released from lava that was deep within the earth. The water cycle is absolutely fascinating

[@RobinCrusoe1952]

The role of graphite in mountain building may be an interesting topic for discussion.

[@GEOGIRL]

I actually have a video all about that! :D kzbin.info/www/bejne/npi9n5mof6yjjZo

[@ColemanCanna]

I've wonder how much pressure is being put on the plates in the Pacific and Atlantic oceans by the movement going on in and on both sides of the Appalachian mountains.

[@cavetroll666]

thanks for the content cheers from Toronto.

[@Canned.bread.25]

This just makes the rare earth hypothesis that much more viable to me. I wonder if plate tectonics are so rare because they require a relatively oversized/overheated core like Earth supposedly has?

[@UteChewb]

Thank you. This is fascinating, and it makes some sense that perhaps the movement of continents due to the fluid flow within the mantle could be subject to variations just as, for example, the magnetic field of the Earth can have reversals due to fluid dynamics in the core.

[@toastyburger]

Does Dr. Stern propose ideas for what triggers the transition between regimes? I assume plate and lid tectonics co-exist during the transition periods (part of Earth has plates and another part has a lid). Is such a state naturally unstable so that it must swing one way or the other? Edit: Thanks for the presentation! I find it fascinating. The possibility that surface water could be necessary for plate tectonics is compelling.

[@GEOGIRL]

From what I understand, the idea is that changes in mantle convection or surface conditions could trigger these transitions... (so kind of anything lol), I think it is an area we still don't understand much... 'the why' as it is in so many areas of ongoing research! :) But at least pepole are out there researching it and getting closer to the answers! :D

[@JimMichels-dy3vm]

We live on a dynamic and constantly changing planet!!

[@davidschaftenaar6530]

0:15 That's a neat little transition you did there 😮😎

[@wmffmw]

Good presentation of information. Nothing new here, except flushing out some details. I learned all this starting in 1970 from MIT and CAL TECH while in the USAF-AFTAC and studies since. Nice charts and summary. Venus-Earth-Mars can be seen as covering the tectonic spectrum across time. Water acts like both a lubricant and an abrasive depending on temperature. A super heated, extremely dense metal saturated column of water is highly corrosive, forms an effective rock splitting process. "Thermionic Acid" if you will, Ph and concentration is both temperature and pressure dependent. Columns, Plumes, Dykes and Volcanoes are a result seen in the Crust or upper surface of the Lithosphere. The idea the Lithosphere and the Mantel are hotter than they should be is an opinion based on assumptions about data. The hypotheses is interesting and a logical construct.

[@michaeleisenberg7867]

Rachel ⛳, I love 💚 all your tectonic 🌋 videos. Fascinating subject. Thank you. 👏👏👏👏👏

[@GEOGIRL]

@@michaeleisenberg7867 thank you! So glad you enjoy these videos, it is a topic I find endlessly fascinating! 😃

[@iamsuzerain3987]

Very interesting video. Thanks for uploading GeoGirl❤👍

[@ShawnoAnDerDonau]

Why hasn't anyone made a 3D model of the Earth's interior with the plates descending and known upwelling of hot spots and plate spreading zones? Seems like there should be adequate info at this point to construct a halfway decent visualization of it.

[@wadehines9971]

I am now a huge fan.

[@nathanmiller5658]

Super video GG. I really learned a lot about an associated technical field.

[@GEOGIRL]

So glad you enjoyed it and learned a lot!!😃

[@annoyed707]

I jumped in, heard "Dr. Stern" and thought 'Lilith'!

[@luciddaze248]

I like this hypothesis! I've always had struggles with plate tectonics historical extrapolations. The ideas here address what I consider logical weak points. Definitely curious to learn more about geological variations that have been suggested.. has anyone started mapping them yet? 😲

[@wavemaker54]

Thanks, quite interesting. Great presentation too!

[@xelaxander]

15:10 Dammit, it's the rocks again!

[@christianhunt7382]

i wonder if its the large scale of water, and the interaction of the heating and the drastic cooling. edit: i posted this just as you said its believed. i agree with them, waters extreme cooling characteristics and effects are hard to ignore.

[@WampusHunter]

I am curious if the Moon and the changing Earth Moon distance would have contributed either directly or with the timing of the tectonic episodes?

[@KalebPeters99]

this is super fascinating!! thank you so much for presenting this awesome paper in such a clear and digestibl format! subscribed! 🎉

[@caseyjones4]

Great video Dr. Geo girl!

[@Tin24k]

Yay new Geogirl video!

[@wantgoodvibes6166]

So clear, very well done, thank you, :)

[@olegoransky5114]

Hi Rachel, like as always very interesting video. It is interesting. how the emergence of plate tectonics causes a complication of life, since 2.2 - 2.1 billion years ago the Francevillian biota appeared, supposedly multicellular, and the late Proterozoic plate tectonics caused a complication of life as an example of the Ediacaran fauna. This time (2.2 - 2.1 billion years ago) also was when the first traces of oxygen appeared in the atmosphere (Great Oxidation Event). What do you think about it?

[@malcolmmarzo2461]

"Power to Save the World" by Gwyneth Cravens made this point: Life on Earth is only possible because of nuclear energy. The fission reactor below us and the fusion reactor above us.

[@Deusexmaschera]

Lithosphere (lithospheric mantle + crust). Long story short: viscosity of rock is exponentially depending on temperature. The first 100 km are conductive, and not convective, thus you have huge temperature difference. So it is rigid and not participating to convection.

[@Broken_robot1986]

That's nice!

[@Greg-l8r]

Love at first sight. I’ll never be bored with ‘Geo Girl’ around.

[@JonathanTucker1ls]

Thank you for yet another interesting video. You make rocks, interesting! Have a great New Year.

[@jakobusphsteyn3500]

Thanks for the further development of the mechanics of plate Techtonics as this is still a fairly new science with a lot more of hypotheses to formulate and test.

[@williammontgrain6544]

Given this understanding, I can easily see how stagnant lid tectonics could be the dominant regime whenever supercontinenents were present and stable.

[@keepmoving1185]

Great content

[@XAirForcedotcom]

Plate of geology served up hot

[@jim.franklin]

Hi Rachel, interesting video, can I please add a few perspectives. I have watched a Lava Lake (Erta Ale) many years ago, and videos of them since and noted how solid plates would form that would float about, sometimes combine and often overwhelmed by upwellings, or "subducted" under larger slabs or the react as they hit the hard edge and the hot material then melts them - it strikes me that this process in the lava lakes is very likely a microcosm of what happened on early Earth so lighter material that "floated" to the top then cooled and started to form crustal materials, this may have been transient at first, but as some sections grouped together, it likely became easier for them to resist the forces around them and survive. Some observations about our near neighbour. Venus has an extremely hot surface temperature (~467°C), which is only a few hundred degrees cooler than the shallow mantle. The surface pressure (~92 bar) is significantly higher than Earth's (1 bar), meaning that the pressure difference between the interior and the surface is lower. This could lead to weaker convection, since the driving force behind convection is often temperature difference (ΔT), and Venus has a smaller ΔT compared to Earth. With less vigorous convection, Venus might not have plate tectonics like Earth. Instead, heat could build up in the mantle over time, leading to episodic, catastrophic resurfacing events (like the theorised global volcanic resurfacing event ~500 million years ago). A smaller ΔP and ΔT might also mean that Venus lacks strong subduction zones and experiences more stagnant lid tectonics, where the lithosphere remains mostly intact and deforms in place rather than breaking into moving plates.Heat may escape primarily via plume-driven volcanism (i.e., upwelling mantle plumes producing large shield volcanoes like Sif Mons), but there is plenty of evidence that Venus also has the Venusian equivlent of Stratovolcanoes - in fact, a recent review of old data has estimated that Venus may have up to 85,000 volcanoes. See the paper here: agupubs.onlinelibrary.wiley.com/doi/10.1029/2023JE007753 There is also growing evidence that Mercury, the Moon and Mars are not as volcanically dead as we thought.

[@guidzoe6258]

Excellent video

[@chrispierce1167]

Very good episode. Thanks.

[@patrickgriffiths889]

Thanks. Very interesting.

[@Deusexmaschera]

On top of that, there is a big discussion on the feasibility of plate tectonic during the early earth. One of the reasons is the following: mantle was too hot. Plate tectonic is mainly driven by the slab pull and within an essentially inviscid mantle slab tends to detach easily ( see Van Hunen, Sizova). I am a bit skeptical on the drip tectonic because most of the information are derived through numerical modelling and there are still not the technical capabilities to fully simulate on the long term these process. From the preliminary results seems likely a self feeding process between melting and generation of residuum. But I m still not fully convinced and also confident of my old results

[@sachamarcet]

I *just* finished writing a report for a lecture series on this (in a Northern European context) I wish I had seen this video beforehand.

[@kyjo72682]

Interesting. It never occurred to me that plate tectonics wasn't common. Possibly another point for the Rare Earth hypothesis..

[@TwoBun]

I'm having a nice time, this is fun!

[@volkerr.]

Being a school kid in the mid 1980s I’ve learned about tectonics. Actually German Alfred Wegener already back in 1912 was the first coming up with this theory.

[@alandyer910]

Fascinating, thank you! I’d be interested in learning more about what current thinking is on the role the giant impact that created the Moon had on shaping Earth’s interior and tectonic cycles, and what effect the continuing presence of a large and once much closer Moon had on Earth and making it habitable. Thanks! 🙏

[@adamredwine774]

Excellent as always

[@anthonyrepetto3474]

this channel is the schist!

[@_andrewvia]

Thank you Dr Phillips. People tend to think in terms of decades. Geology really exercises the mind. The room you're in has some beautiful architecture. You must be on campus.

[@GEOGIRL]

Thank you! Haha actually it is a room in my geologists parents house ;) (I’m visiting for the holidays). They have lots of beautiful artwork and rock shelves of course!

[@ericclayton6287]

@@GEOGIRL a book I often recommend is The Annals of the Former World by John McPhee. It amounts to a 101 course in a lyric fashion and you get to spend time with some of the greats of late 20th century U S geology.

[@ElkoJohn]

Fascinating

[@LuisAldamiz]

Also what about the Moon? It's been claimed (and has a lot of logic) that tidal pull-push by the Moon in a long cycle is what drives plate tectonics. And the Moon was there since the Hadean, since the Earth can be called such thing!

[@johnjakson444]

In the 70s when I was in a technical high school, and with the 3 or 4 TV channels of the UK, there was no mention of plate tectonics at all, the best schooling of science has come decades later.

[@davesilkstone6912]

Would the collision with Theia (that created the Moon) have affected the evoution of tectonics, e.g. By removing upper layers of the Earth / cracking the shell?

[@danielcomeau9880]

Granite floats on a sphere of red hot metal.

[@rawmilkmike]

Good to hear there are new discoveries. There are many theories and conjectures that need to be reevaluated. There is just so much scientific dogma to deal with. New ideas are often shut down before they even start.

[@Swede_4_DJT]

Greetings from Sweden! Subscriber from today! Awesome topics!

[@jeshika22]

Right off the bat I was going to comment on how liquid water is a major difference but then you went ahead and mentioned it anyway. I would also like to point out one key potential factor could be the theory that the Earth went through a complete re-melting after the collision with Thea, which could be considered somewhat of a distillation process, which in turn then could maybe cause even greater diversity and variation of rock densities. And also, Earth is the only planet with a substantially large moon, although certainly Jupiter's moons experience much more extreme tidal forces, there might be some affect from the moon that could be influencing plates rather than lid.

[@hgbugalou]

Earth having an abundance of liquid water on the surface is almost certainly why we have plate tectonics and other planets do not IMO. It will be interesting to see if moons of the gas giants with liquid oceans present under ice have plate tectonics as well.

[@GEOGIRL]

There are some hypotheses that indicate Europa and other icy moons may have ice plate tectonics! How cool!!😃

[@ChristopheSmet123321]

@@GEOGIRL Very cool indeed! But how could we ever test such a hypothesis? Finding evidence for plate tectonics underneath that ice sounds quite difficult, if not impossible, no?

[@ArodWinterbornSteed]

Drip tectonics sounds like a lava lamp…

[@robertwhite1810]

Love your presentations!

[@SayBinidus]

Ganymede appears to possibly have had some plate-like techtonics early on in its history. Its surface almost seems to have some continental and rift regions.