Exotic L - Karin Sigloch

well good morning everybody the local time is 8 44. in the morning welcome to the backyard here in ellensburg washington our program on karen siglo will begin at the top of the hour about 15 minutes from now but we're going to use the first 15 minutes here together just to say hi do some thank yous make sure that we're functional the usual routine around here our session last time was less than 48 hours ago friday afternoon we talked about rengelia and it's time to take a break from building terrains and to talk about some exciting new ideas are we functional good morning rini and frederick new mexico 5x5 says frederick vancouver washington dean sarah's in mill creek washington the geekes in alabama dayton ohio checking in new orleans perup nevada a stormy coast of england portsmouth hello stephen thank you for the descriptive description what uh the netherlands east texas marion virginia hello eric connecticut a bunch of stuff flew by edmonton another england jim is from prineville oregon uh a town in ontario nashville tennessee salmo bc wisconsin rapids good picture and sound says bob that's always nice to see very comforting the sun hasn't quite broken over the neighbor's tree but i think we'll get some sun here in a few minutes it's it's yeah 28 degrees right now fahrenheit half moon bay hello pat in boise diamond bar california edmonton alberta so i'm glad that the sound is fine um yeah we got snow on the ridges but no snow in town over the weekend i guess that was friday night saturday morning templeton california oh liz is back from the store great wonderful uh i got a bunch of thank yous uh i'm just i continue to see the comments scrolling by so i assume we're okay uh thank yous i'm gonna start with um something we've been a topic we've been experiencing or exploring together i promise i won't do this every show but couple shows ago i shared with you because there was a theme to that program in the alexander terrain and an immigrant from northern europe and i talked about my great great grandfather nicholas who came from elm switzerland and crossed the atlantic and made it to new glarus wisconsin where all my people are my cousins etc today and i shared in that program some two major mysteries that remained in the f remained past tense remained in the family one was uh what year exactly did nicholas come over we wouldn't have been able to find that and then what port so i shared with you last show that i wanted to thank patrick and matthias in switzerland patrick especially who has all this amazing info and patrick said the mystery is solved for your family monday april 4th 1864 is when your great-great-grandfather nicholas left elm and we have his signature in the log book in elm and but he couldn't help us with the port and he couldn't find a name so thanks today to margaret in portland and bart in rich in richland in tri-cities washington they're not related margaret and bart i got two separate emails from those two folks and they said we got it let me read you bart's email he watched in other words friday's show and emailed uh you know saturday morning i think it was no friday night just a few hours after we quit hi nick i believe i have found the new york arrival manifest for your great great grandfather there was an error in the transcript when they converted to digital of the original ship's manifest which arrived may 4th 1864. so exactly one month to the day after nicholas left elm he arrived in castle garden the port at new york and he's listed as in the digital forum m tentner but the original document is definitely zentner the first initial hard to make out but he was listed as age 27 born in 1837 that that that fits and he listed himself as a minor from germany as i understand it this is this is bart talking as i understand it it was hard it was hard to leave switzerland at that time so he might have said he was from germany and the ship the l edinburgh left from liverpool and made a stop at queenstown ireland in uh includes margaret so that's the other mystery solved here it is isn't the internet an amazing thing here's the document may 4th 1864. and there's nick's signature or the clerk writing and kind of can't make that out kind of a thing but i i don't want to get emotional again but i mean this is yet another reason to do these live streams you can solve mysteries that have existed for more than 100 years in our family so thank you to you folks and thanks everybody for for trying to help with that wow amazing stuff a bottle of wine for liz it's empty a bottle of wine for liz who can share it with nick if she likes she didn't since she puts up with so much thank you so much larry and karen western washington university geology alums about my vintage so thanks to you guys she enjoyed the wine brogan from seattle brogan remembers the cinder cone volcano live stream where i had a hot air popper and i made a cinder cone using hot air popper uh so brogan made his own cinder cone maker and dropped off some uh beef jerky from owens meats in cleoelum this episode of nick from home brought to you by owens meats you gotta love it and uh a patriot power cell which looks like man i think i need my toque out here patriot power cell thank you brogan very much sorry i missed you jeff from vinman's brought over a bunch of t-shirts i don't know what i'm going to do with them i already have mine liz has one this episode of nick from home brought to you by vinman's bakery you've got to love it and thank you for all the gift cards all the vinmen's gift cards i come in there with a whole stack of inman's gift cards you know like i don't know how much is on this one let's you know they get a kick out of it when i bring that in uh how we doing i got more thank yous here so uh shipped from savannah georgia the savannah candy kitchen and this was ordered online by timothy kirk whoop sorry tim sorry tim in i think you're in bonnie lake is that right tim's in bonnie lake nick i hope you and liz enjoy the german chocolate cake best wishes thanks for all you do thank you tim and tim actually sent in a field report video which i will be sharing once we get to the north cascades but we're not quite there yet so you want to see the cake oh man the way it's going to be going back on we might have to we might have to freeze this and uh wait till we have some of our kids home all of our kids home i think that's how i got an extra 19 pounds last spring remember that huge carrot cake and some other things so we we sampled it tim it's delicious savannah candy kitchen was it thank you very much and one more thank you and one more thank you i mean i won't comment on how embarrassing it is to get all these presents and i don't deserve all this but you've already heard that from me so i'll just i'll just enjoy these presents every day there's something coming in professor ned you have been displaying some of the crappiest clipboards i've ever seen sorry patrick thought you could use some new ones maybe the lovely liz could have fur these are made from recycled pallets so please excuse the occasional nail hole or defect thanks for being who you are dave age 71. so we have 11 new clipboards from dave and liz already picked out hers she's got it at school so i'm going to put a couple to use this morning dave thank you very much i think i do want to grab my hat that sun's not going to come over for another 10 minutes uh we doing okay can i check one more time five by five five by five yeah i'm to be honest i'm pretty tricked out here now with uh i'm gonna jinx it but i'm pretty tricked out with uh towny steve helping me out so if i see buffering i'm not gonna be as apt to freak out on my end i'll just assume it's you so um no offense but uh i think the days of chasing around the backyard and doing this and doing that as long as i see a bunch of five by fives i'm gonna be i'm just gonna be rolling with it okay i got two minutes and i really gotta i'm excited for this morning but i'm also intimidated by this morning and you'll see what i mean and it's all brand new to me so i got my got my old got my little notes let's see how this one goes i'm gonna get my hat give me a couple minutes and we will begin thank you for joining us this morning hot mike okay karin mitch mahola nick siglock sieglock mahalo nick geophysics are you effing kidding me i'm in the kitchen hot mike what the h there isn't supposed to be any wind this morning use a rock as a paperweight thank you i didn't realize rocks were heavy i need another 30 seconds if you wouldn't mind uh you okay here goes nothing well pleasant good morning to you all welcome to ellensburg washington usa my name is nick zettner i teach geology here at the college in town ellensburg washington usa central washington university and we're talking about some research this morning that is tremendously exciting much of it brand new to me i have my work cut out for me this morning and this is a very different kind of a show as you might imagine it's named after a person not a terrain really for the first time so i'm going to be concentrating extra hard and let me say right up front that i suppose there'll be a moment or two maybe more than a couple moments where i'll go oh wait a minute that's that's not right because i'm still trying to get this stuff to stick it's not a disclaimer i'm just letting you know that i've been learning a lot recently you know a pretty deep dive in the last 48 hours but over the last couple of months i've been kind of picking up concepts here and there and the payoff potentially is getting our mind at least for a first pass wrapped around one of the most exciting new developments in geology in western north america not depend on depends on who you talk to but i'm a fan and i'm excited officially and my humble goal this morning is to at least introduce you to this brand new line of work we have a new tool essentially to help us understand exotic terrain history so to get rolling let's actually what let's actually go to mappy mcmap and remind ourselves where we are and i'm going to do this real quick because this could be a three-hour show if i if i have a slow pace so i i gotta make sure i stay nice and brisk no problem with the weather this morning ah yeah hesitating already for goodness sake mapping mcmap so i'm not introducing a new color this morning we're not adding a new terrain but we are taking a very quick look especially for those that are brand new to us to what we've done so far in the last half a dozen shows or so what's with the wind man well look at what i have here dave i have a brand new clipboard morning all right so uh i'm not gonna spend 20 minutes on this but i'm reminding you that we've been building british columbia piece by piece and i'm review reminding you that we had some colors that we introduced for our series and we do have the insular super terrain the intermontane super terrain and these terrain names are individual there's a show for each of these there's a live stream for each of these recently quinnelia cash creeks to kenya alexander and rangeli and these two guys are intertwined these three came in together we don't need to go through that again and the two major dates we have settled on so far in this series the intermontane super terrain these three guys added to old north america 170 million years ago the insular super terrain added 100 million years ago i still like that date i was a little hesitant on friday i like it i i'm pretty sure i still like it now these are events accretion events that take more than a million years but just for simplicity's sake and you know that's my deal i'm an introductory geology teacher but i try my best to use new stuff and we're definitely doing that this morning so there it is one more time a reminder color wise on the map and then a reminder in cross-section cartoonishly our story now to this point and i've said this a number of times recently i have avoided oceanic plates i've avoided names of ocean plates what directions they were moving where the trench was what the subduction looked like and there was a reason for it there was a reason i avoided the ocean plate discussion in other words i avoided the conveyor belts that brought these terrains to north america and i can't hold it no i will hold it all right so the reason is this morning there's a completely new idea set of ideas involving the accretion of these terrains not the details not the dates not the rocks but the mechanism for a creating the terrain material to the western edge of north america now most famously in british columbia where things are exposed but eventually when we get to the north cascades which is starting next time by the way well i'm going to the north the san juan islands going to the san juan islands in washington so for those that have been patiently waiting to use your book and you've got it with you every time that we're watching these together live we're using this thing read the section if you want to read ahead read the section on the san juan islands written by darrell cowan daryl's a co-author of this book daryl was with us by the way during the live chat on friday and i talked him on the phone yesterday he may be here again today but daryl is is mr san juan islands train boy and so we will um we will go there finally to washington and some exotic terrains in washington but the concept is boy we got a brand new we got i think it's i don't think it's overstating we have a revolution right now in thought pretty much as exciting as as the 1960s in a way as far as what we're talking about here in the american west and i think i'm going to start that way my first geology 101 class was in 1984 university of wisconsin and it was the first week maybe it was the first day and the professor basically said i've been here at university of washington since the 1950s the 1960s were an ex tremendously exciting time this is 1984 when i'm sitting in the lecture room and he said you missed it you missed all the excitement the textbooks were thrown out we wrote new ones the plate tectonic revolution happened in the 1960s and early 1970s and you missed it now i don't know if you actually said those words but that was the message that i received i remember kind of being bummed out like dang i wish i was here 20 years earlier well there is something going on right now and many geologists who i've talked to in the last month are unaware of karen unaware of her work if they've heard of her they kind of have a general concept but that's about it and so i think there's enough here that possibly in 10 years 15 years this stuff we're talking about this morning will be used in the geology 101 textbooks which is my world okay so there is a set of old ideas that uh many watching eventually will uh cling to probably that's how this business this change of thought works you know and karen is going to help us see some slab walls i'll explain down in the mantle and then we will land on karen's new ideas now right off the bat i have to say it's more than current it's a team we're talking about this morning but i didn't want to put two names on the show it doesn't fit in my little chalkboard when i advertise these live streams so karin siglock from the university of oxford i wrote that somewhere it doesn't matter i'll find it karen siglock from university of oxford in england and mitch maholinic from the british columbia geological society or something like that and mitch has 30 plus years of mapping exotic terrains on our map in fact remember the string bean and jackknifing the string bean and cash creek in between and we talked about joanne but it was mitch 30 years ago who's talking about these terrains and trying to work out these geometries and here's mitch with some work here in the yukon alexander terrain and coming through the arctic mitch is all over all of this bedrock he's a field mapper so we have mitch from bc with all this kind of bang on rocks bedrock geology experience and mitch is hooking up with karen who's from germany originally and she's coming from the world of geophysics and i'll let this play out a little bit more in just a bit so it's karen and mitch who are going to help us with this new set of ideas that i'm hoping to communicate now i said i was going to be brisk and pace it's already 10 after they are i'm still like introducing the topic you know me that's how this is going to work we finally got some sun i'm going to heat up a little bit and get excited but i can't speed myself up too much or i'll start making a bunch of mistakes so hey man settle in this can be a while okay let's start with the old idea again some will say it's still the idea it's not an old idea all right well you know i've been teaching for 30 years and i have this course pack of all these hand-drawn sketches that i uh share with my students and this page 33 is on the final exam hey are you a geology 101 student of mine right now this is our lecture tomorrow morning turns out and you're gonna have to draw page 33 on the final exam i don't even care if you understand it you just have to practice drawing this thing and that's how important this is we're talking about western north america 40 million years ago 20 million years ago and today and this is still viewed as accurate so let's not get carried away this morning this is still i'm starting with kind of setting the stage of what i normally teach and what i might want to be changing in the next i don't know as soon as uh two weeks from now in my geology 101 class here at central but i'm not changing this this is recent enough the last 40 million years this is recent enough that we're not going to we're not going to monkey with this but what we're looking at here is a map i'm not going to spend a lot of time talking about it but this is a fairlawn plate that's moving eastward and subducting beneath north america it's a collision between the ocean fair plate and continental north american plate and these x's are composite cone volcanoes we have a volcanic ark and an oceanic trench offshore let me help you with a couple of cross sections to just visualize what i have been teaching forever and will continue to teach hey i got another clipboard i only got nine more clipboards to go dave thanks so here is uh that map again and now we are to the old idea that if we go back 40 million years that's fine this this view of north of of oceanic fairlawn plates subducting beneath north america totally fine but what i've been teaching for a long time and i'm going to change it is that we have 180 million years of pharaoh on plate coming at north america now do you remember what these black teeth mean that means we have subduction of the farallon plate going diving beneath north america to the east eastward subduction let me let me pause and hit this hard that what does that look like underground looks like this west and east moving fairlawn plate it's subducting fine it's subducting towards the east it's diving towards the east eastward subduction let me state very as clearly as i can what the old idea has been since i started learning geology in the mid 1980s the old idea has always been the farallon plate used to be absolutely huge a simple large ocean conveyor belt getting created at the east pacific rise far distant from the west coast of north america and here's this monster-sized fairlawn plate coming at north america and subducting beneath it again eastward subduction what's this got to do with our a to z series on exotic terrains well as i've been teaching for 30 years all you got to do is just get some exotic terrains on this conveyor belt and have those things come in a bunch of chocolate chip cookies just get the big lumps of dough on there and just bring those bring those puppies right in and as you subduct the oceanic farallon plate beneath north america forget this you're just going to bring a bunch of those terrains in another sketch of the same thing we're about to talk about ophiolites next week or maybe a week and a half kind of forget but again this is eastward subduction another sketch showing the same thing this is the old idea that has been around for 50 years now just to introduce the concept are all subduction zones in the world eastward subduction no here's an example of a place where we have ocean plate moving west diving to the west westward subduction so now i really can't hold it all right new idea and by all i mean karin and mitch's new idea is that for a time not the entire history of the last 200 million years but for a time we did not have westward subduction of a huge simple oceanic farallon plate i'm cutting right to the main message of the entire program ladies and gentlemen are you ready to hear it again this model is too simple this model of a one huge oceanic fairlawn plate subducting eastward underneath north america for the last 200 million years is too simple and we now have data in the lower mantle thanks to karen's work to suggest that instead of this being like the andes instead of this being an always andean margin instead there was an archipelago of island arcs out in this area of the pacific that was more complicated but actually involved i can't hold it i was going to build and build to this but i'm just going to do it instead of the terrains coming towards north america and adding to north america the new idea is when we have had westward subduction north america is approaching the terrains i'm just going to say it verbally you're driving down the road at a high rate of speed it's an old deserted county road you're really rolling you've got a windshield on your vehicle you're rolling down the road you with me now suddenly we're going to get some baked potatoes to splatter on your windshield don't ask me why just play with me would you the question is are those baked potatoes accreting to your windshield the result of the baked potatoes being thrown at your windshield as you drive in other words the baked potatoes are coming at your windshield or are the baked potatoes the terrains fixed in space hanging i don't know are they in tin foil they're hanging out there in in the air and you're accreting the baked potatoes onto your windshield because you are coming at the baked potatoes you're still going to splatter the baked potatoes on your windshield but it's a question of who's moving the new idea and i'll show you the evidence for it i can't just give you the idea and say thanks for listening the idea which is exciting new data in the lower mantle of our planet makes a compelling case for the insular super terrain to be built out in the ocean and fixed and north america approaching the insular super terrain as opposed to the insular super terrain coming at us before we get lost in paper shuffling everything else i'm hoping to convey that message over and over again this morning and i really don't trust myself to be honest so i wanted to make sure we got there at least verbally and then we've got all sorts of uh images and other things to put together okay that was a big moment i don't know how much of it you got let's continue okay old idea what else do i have from folder one which is talking about the old idea he asks himself uh right okay now the earlier days of excitement in the late 1960s and early 1970s tonya atwater uh was doing some amazing work and one of the most exciting scientific papers ever was published in 1970 by tonya atwater no relation to brian by the way and she was working with the sea floor of the pacific and these magnetic stripes and working out seafloor spreading patterns and the upshot of her work which was tremendously exciting was working out the fact that the san andreas fault is a thing and here's the history of the san andreas fault and i don't know have you seen a map like this this is a map of the sea floor of the atlantic ocean and the pacific ocean and these colors are talking there's going to be a lot of colors this morning hang with me the colors are talking about the age of the basalt on the atlantic ocean floor and this was exciting in the 1960s for sure that the basalt on the atlantic ocean floor and then in the pacific ocean floor uh was discovered to be not all the same age was not static but instead the youngest basalt was formed in the middle of the atlantic ocean and we know exactly how much spreading there has been in the last 180 million years on the atlantic ocean floor that's important because we know exactly because of this complete record of the breakup of pangaea we know exactly where north america is located at each little moment in time in the last one 180 million years based on this complete record now what tonya was saying is look at this we have spreading of the east pacific rise actually faster than the mid-atlantic ridge that's why these color bands are wider but the big message is if we go back in time and send north america and south america back uh to pangea time can you do that with me can we go back and this is today right but if we go back in time 200 million years there is no atlantic ocean floor these guys are connected and the point is there was a lot more ocean crust this side of the east pacific rise in other words this red to blue red to blue 180 million years of sea floor there must have been a matching red to blue that is mostly been destroyed and you're like well how do you destroy ocean plate material you freaking send it down a subduction zone whether it's eastward subduction or western subduction you're going to destroy or consume ocean floor material now here's another way to say why this is so exciting this morning i've always taught that when you destroy ocean crust you truly destroy it you send it down a subduction zone and it changes state whatever that means and it just kind of assimilates back into the asthenosphere are you aware that in the lower mantle we still have some of that subducted slab material in fact we have all of it let me repeat that if we're destroying all this pacific ocean floor that was created at these specific rise all the yellows and the greens and the blues that were clearly on the other side of these specific garage where did that stuff go well it went back into the earth but did it get destroyed we will see that those slabs are still down there they don't change state and just kind of magically convert back into the asthenosphere they stay a rigid slab and using the geophysics that karen's been able to work out we have visuals so i'm ahead of myself just a little bit again i want to make sure that you can see that this is still an accurate story at least the last 40 the most recent 40 million years this is tonya's 1970 very famous paper and if you're like i have no idea what i'm looking at how can i orient this i am orienting it correctly so this is north america's west coast 20 million years ago north america's west coast 40 million years ago 60 million years ago 80 million years ago and tonya for the first time introduced the kula plate which we still know it was a thing uh but she has a migrating triple junction she has the san andreas fault beginning not our topic today but i'm not undoing all of that very important work what i'm also not undoing but i'm helping us see differently because of karn and mitch's work is california geology so of course california people who've spent their whole career working on this very famous native ark story that's the phrase used that uh if you like the old idea of the old farallon plate subducting beneath california for 200 million years or whatever then you have the franciscan formation this melange the subduction complex this is their westernmost california here's where the volcanoes the volcanic ark with eastward subduction eastward subduction of the farallon plate for a hell of a long time more than a hundred million years the old model more than a hundred million years of eastward subduction of the oceanic fairlawn plate beneath california and hell if it's in california you must be everywhere was the thought this native volcanic ark choosing the words carefully now because i still don't think i totally get it but this native volcanic ark where the sierra nevada mountains are today by the way if you're not sure where we are the plutonic rocks of the magma chambers are now in the high sierra if you know yosemite et cetera but my point is we still karen and mitch still haven't this right an eastward subduction to make the native ark of the sierras but it wasn't consistent in california and you know i can just play along with me we'll see if that can work that's still fuzzy in my brain it's one of the fuzzy parts of this presentation it the old college try i'm going to try to keep moving i i'm going to pause actually are we functional first of all and are we are we communicating at all do you feel like basically are we still communicating thank you okay so you take a classic publication like this a streetcar to subduction by clyde warhoftig talking about eastward subduction of the fairlawn plate creating california geology we are tweaking that let's get to the actual data and the concept and how it has anything to do with the insular super terrain which is the whole reason for plugging this in here i mean we had a nice progress going with with building these terrains and building western north america and i decided to put that all to a screeching halt and insert this karn and mitch show now why because it has everything to do with the creating the insular super terrain 100 million years ago and again we came to the insular super terrain the insular super terrain did not come to us what's the evidence talking about the fruitcake by the way from collins street bakery thank you darth madison wisconsin baby there we go so i emailed both of these guys the subject in the email was fan letter and i i got beautiful replies from each of them independently and i'm going to share some of that email with you to give you a sense of kind of the personal touch on this and what what they're currently working on here's karen now i don't want to overstate this but geologists are tribal like most of us we have our little groups we have our little associations and oh yeah i respect that person yeah such and such worked with that person and so karen's kind of an outsider more than kind of actually she didn't study geology as an undergrad she didn't understand study geology as a master's student she was an engineering student electrical and computer engineering and it's so bright that she decided well i'll start working on geology for a phd so this is an interesting article from 2014 uh karen siglock a geophysicist at the university of oxford in england grew up in germany her career may seem an unusual choice for an engineering major but siegl uh believed she couldn't have found a job more thrilling after all she is illuminating the very rock beneath our feet a place just as dynamic and yet less studied than outer space that's been one of my running comments in my classes i'm like we don't know anything about the mantle i'm talking to my kids now over the last 30 years my students and i would always say you know before i retire it would be really nice to be able to communicate with you something that we know down in the mantle to help us understand plate tectonics and i always remember this kid like four or five years ago he's like time's running out before i retire it's like aren't you a retired yet you're pushing 60 times running out bro well here it is so uh karen uh moved to the u.s to work at bell labs in new jersey it was an incredibly creative very heady very fun time she was working with cell phone technology bell labs although the work satisfier she didn't think she wanted to spend her career studying cell phones here's a quote from karen in this article so i asked the lunch table what should i do her colleagues pushed her to consider subjects beyond pure engineering they said you have to find a beautiful field for yourself something that appeals to you on a gut level she remembers she took the advice to heart considering doctoral programs in space weather and neuroscience before zeroing in on geoscience lab at princeton i mean there's only a few folks who have that kind of brain power to just decide to go wherever they want and just excel immediately that appears to be the case here there she could use her knowledge of wave forms to peer into the deepest recesses of the earth places people had theorized about but never seen i just thought that would be a great privilege she says i'm reading this because i don't understand geophysics at all at princeton siglock perfected the computational techniques she would need to turn seismic signals into 3-d pictures of the earth's interior and with help from her thesis advisor gus nolet she began developing new algorithms that could produce high resolution images to test them the scientists needed data they set to choo they they they set the set of data they chose came from a grid of 400 movable seismometers called the us array which was slowly making its way across the contiguous u.s beginning in california in 2004 and ending in 2014 seismologists began burying basketball-sized instruments in two meter deep holes where they remained for two years before being dug up and transplanted further east when siglock got a hold of the data in 2006 the array had scanned only the westernmost states but that was enough to take a snapshot of what lay beneath so it's not an accident that she decided to work out here in the american west we had this u.s array with this with this geodetic informa this seismology information about how earthquake waves are traveling through different layers in the earth including the mantle okay and then the rest is giving away the story so let's do a very quick look at the interior of the earth and i have a prop of course so here's one way to do this uh you know that there's a crust a mantle in a core inside of our planet uh the moho is a boundary between the crust and the mantle the crust is not all 70 kilometers thick it's thinner in the ocean crust but who cares right now it's the mantle that oh this is going somewhere in the mantle our our focus is the mantle it's really the lower mantle so these are depths and kilometers below the surface and we're going to be in the lower mantle and i can't hold it here's one of the famous things that karen was able to find in the last 15 years a vertical slab a former ocean floor on the pacific that's now hanging down there vertically and it's squiggly like this i think it's like 500 kilometers thick this this wall she calls them a slab wall some people call them slab curtains and there's a bunch of these things but this is the one we're going to focus on in fact that's what this is on a map but i'll get to it in just a second and then here's the core and here's the distance to the center of the earth we don't care about inner and outer core we're just talking about this lowest mantle so there probably have been amazing advancements in the lower mantle and seeing into the lower mantle and understanding what's going on down there but i haven't been using it i haven't been paying attention to that and i only know about this work by karen in her three-dimensional modeling of the lower mantle because it applies to the western us and specifically the exotic terrain story so i don't know if you have seen anything like this this is kind of the old way that geophysical seismic models i'm probably using the wrong phrase are shown kind of 2d tomography that's a big word for us today tomography is studying the inside of our planet indirectly by studying how seismic waves travel through different things in the earth and the this is the traditional way of showing it so it's a two dimensional slice which never worked for my brain by the way i would see talks like this and i would just go blank when i would see something like this they go this is a depth of you know 600 kilometer depth and we're taking a slice and the blue are the seismically flat fast mediums and the red are the seismically slow mediums and like what and then they say well the seismically fast stuff is is subducted ocean material i kind of like perk up like oh okay but i couldn't really see it it's just a two dimensional slice i can't like if you take a two-dimensional slice through a belly of an elephant and then you show them the slice they're like what do you think i'm like i don't know is that like a dog is that like a tree no it's an elephant you can't you see it it's like a two two two-dimensional slice so using karen's black magic i have no idea how she's able to do it and when we get to q a i'll pass on all those questions but using her engineering background seismology whatever she has a new way to present what's inside of the earth in three dimensions three-dimensional tomography and again we're looking at colors now these colors are different and this is our first crack at it um i think she even changes her colors as the papers go on so i don't know i'll let's there's a three-dimensional look at that okay so i don't know i brought an apple to show you the inside of the earth we don't need it okay you've got the depth what i will no i will i will use that apple damn it i brought it out every time i bring a prop out and then i'm ready to use it i'm like this is stupid why am i showing this everybody can see what i'm talking about this is an apple the apple is like the inside of the earth ooh ah there's a the apple has a core i'm from washington right there's the core of the earth we don't care about it there's the crust of the earth we don't care about it that's the app the thickness of the skin of the apple we care about should have brought a different color i don't have you ever drawn on an apple with a sharpie i haven't either it doesn't really work what i tried to draw is the boundary between the upper mantle and the lower mantle this is really not working but why not i'll try it anyway oh sorry patrick screw it there are vertical i don't know what do i have nothing pine needles okay who is this clown in the lower mantle it's not homogeneous and as you look at earthquake waves traveling through the lower mantle you can find seismically fast slabs that everyone it's not just a new idea everyone agrees is is formerly ocean crust that has been returned into the earth but has remained a consistent slab and it sinks all the way down to the base of the lower mantle and it starts piling up like what do you mean piling up well this is a this is not just a a finger that's sinking it's a whole plate that's sinking but it's rigid so we're subducting now now we're in fantasyland now okay we're having an ocean plate enter a trench we don't care yet if it's eastward or westward subducting it's it's going to start sinking vertically that's a surprise to me uh and then we get this sinking slab down through the mantle it's still a freaking slab and i think it goes all the way to the very bottom part of the mantle and then it starts folding on itself i can't do it with my hand i can fold it this way and then i fold it that way and i'm going to make like this this ribbon candy almost as we continue to have this vertical ocean slab diving through the mantle and then landing in the very bottom of the mantle it's going to fold up and i was like i can kind of picture that where's folder too hang on hang on patrick i don't want to give too much of it away but it's truly slab material that has sunk through the mantle and then it folds up like this so these slab walls are thick five times thicker this slab wall or this slab curtain that was found are they still there no oh yeah these slab walls in the lower mantle are five times thicker i mean they're vertical they're five times thicker than the ocean crust was originally so how do you explain that well another prop have you gone to a self-serve frozen yogurt place thing piles up right i went there yesterday i took some video of her doing it you can't do it self-serve anymore because of the pandemic of the virus makes sense so she's like you can't do it yourself i'm like what okay would you please do it so that's the best analogy i have for something coming down a a sheet now not not a single finger but a sheet of material and piling up and it's much thicker because of the piling up because of the the the rigidness of the material i also did chocolate by the way the salt you know okay i think i'm done with the props i'm not going to sweat that you're tuning out or like losing focus or whatever i just got to keep rolling but we're finally to the data and the imagery that karen has been able to find you ready this is looking down this is looking down on a map into the lower mantle and this is one of the slab walls that today is beneath the east coast of north america and there's another obvious slab of idaho okay so north america from canada down to the caribbean essentially down we'll just call it the east coast slab and then this idaho slab let's look at the idaho slab first it's easier to understand colors now from karen and some of her papers so this color is just talking about depth here's what i mean by three-dimensional tomography so this is the american west ignore the yellowstone hotspot even though you probably want to be fixated on it let's try to ignore it please the point is this slab wall in the lower mantle what i'm calling idaho she's calling it a cascade root doesn't matter it does matter but let's just cut let's keep our verbiage as simple as possible she has been able to connect that idaho slab curtain or slab wall all the way up to today's juan de fuca plate which is today subducting eastward beneath the pacific northwest so this truly is farallon slab as she calls it i just have to say very quickly that i i've been working with the kula reconstructions uh six months ago and i wonder how much of this is cool it doesn't matter for us okay so this is this is connected to uh today's eastward subduction i mean patrick gave me a beautiful map no cross-section i mean we do know that this is a real thing today right the eastward subduction of the juan de fuca plate is going beneath oh god the wind's picking up it's going beneath the pacific northwest and diving and we have all sorts of earthquake evidence along that plate margin the great earthquakes of brian atwater etc that's all nobody's arguing that we have this and the question is what happens to this when it goes very very deep beneath the crust and even into the mantle and the answer is the image i just showed you which has blown away okay but there's another slab wall you ready this is the good stuff this is the excitement if this is a slab wall beneath idaho is that it hey i just found a 20 bill in the ground so here's the idaho slab wall that continues all the way down to the lower mantle and this is the quote unquote farallon plate but if that's the fairlawn plate what in the heck is this thing it's not at all to this idaho slab another image of the idahos lab going from juan de fuca all the way down to the lower isn't this amazing i didn't i don't think anybody really was able to see this subducted slab going all the way down to the core mantle boundary okay this one's going to be a struggle but i want to show it to you anyway oh let me do it this way so i'm going to show you a little youtube clip of karen speaking to a group of geologists in 2014 and she does this and i'm going to try to do it verbally with you right now why didn't i draw north america on this thing you'll see in just a second but i'm telling you verbally that this is basically underneath new york city east coast of north america right and this thing's underneath idaho so this image i'm about to show you from one of car and student's most recent papers is basically hovering out here and looking from a goodyear blimp uh westward over the continent of north america but peering down into the lower mantle what say it again we're going to look this way with this image you're like oh my god what am i looking at well just for a second let me turn it to something that you'd recognize here's florida here's new york cape cod newfoundland okay that white line is the east coast of north america's continent but do you want to keep it like this we can do that here's this slab curtain so deep beneath north america and then here's the other guy the idaho slab so you're like and it's a little bit different in canada versus southern us but i feel like my my gut feeling says i gotta cut to it so here we go what is this slab if it's not the farallon plate that's the key message of this whole talk is there an explanation for this other slab that's bigger it's a longer curtain this is thousands of miles long sitting down there it's not connected to the farallon slab so what in the world is it first of all here it is in cross-section okay so we're not picking a specific time now we have the i'm looking at this backwards but hopefully it works this is north uh new york city over here on the east coast of north america here's the west coast of north america here's this thing like huh question mark i don't get it and here's the idaho slab curtain that's connected to the subduction of the juan de fuca plate that continues and notice that this thing again color is depth so we're into the lower mantle this is the upper mantle notice that in the lower mantle the idaho curtain is vertical and then it kind of smears uh as north america is drifting over the top we're finally to the to the demonstration that i have in mind and i'm going to soldier on regardless if we're feeling comfortable or not you've tried to visualize it mentally maybe i can help here to be honest i forgot i had these so here's the what we'll call the east coast slab curtain in the lower mantle and here's the idaho slab that's the cascade root slab that's connected to what's going on offshore today and here it's upside down the same two slabs the slab walls but obviously this thing over here is a cross section and i'm trying to set you up for the main message before we kind of back away from the real hard thinking here we're still wondering what is this thing if it's not the farallon thing that's abducted like remember the old idea said that we had a continuous eastward subduction of the theralon plate for 200 million years so why don't we just see a huge kind of angled slab of farallon and nothing else why do we have this whole other thing which is even bigger than this thing and deeper i might add and does not have a connection to a subducting plate today all right hopefully a few of you are ahead of me but just in case you're not white board just fell apart remember that we know where north america was on the planet precisely at different snapshots of time since pangaea started to break apart and so north america may very well be sitting on top of these two slabs today but what if we go back to the time that we're actually bringing in exotic terrains do you remember the timing that we had earlier than 100 million years ago right the work we've been doing with british columbia exotic terrains the inter montane the insular super terrain those were added 170 million years ago and 100 million years ago well where was north america 170 million years ago and the answer is out here north america this thing's north america now okay new york city is over here on the east coast of north america so if i go back to 170 million years ago that slab is diving vertically out in the pacific and you're like wait a minute i thought this was the east coast slab curtain or slab wall it is because today north america is sitting like this on top of it these things are almost like hot spots what do you mean they're not exactly like hot spots because they are they have their sheets instead of individual points but they are like hot spots in the case that they are fixed once these slab curtains get established once you start pulling down on the handle and the frozen yogurt starts piling up that has a momentum of its own and if you move a plate over the top of it it's still a vertical slab that's deep a vertical slab curtain or slab wall that's deep just in case you're still with me let me say it one more time we have for the first time i'm going to say it differently i'm going to get really excited now damn it i want to rip off my clothes i'm so excited here we go using paleomagnetic evidence from 50 years ago merle back ted irving and others there was excitement among a certain community because the old latitude the old potential latitude of an exotic terrain was being documented by the paleomagnetic signature of the magnetite grains inside of a plutonic igneous rock oh what's that what do we got okay well we got a granite that must have crystallized either 17 degrees north latitude or 17 degrees south latitude from paleo mag all we can do is get a former uh latitude of that exotic terrain in the pacific somewhere kind of the same with fossils again i'm talking about 40 50 years ago what's that we got coral reefs in this limestone in this exotic terrain the cache creek or whatever we have to be at a certain latitude closer to the equator do you realize what we're doing here for the first time with karen and mitch's work we're actually able to come up with a former longitude not latitude a former longitude of some of these exotic terrains out in the ocean you're like i don't see how you're doing that well let me try again north america 170 million years ago by the way which karn and mitch agree must have been an eastward subduction this is advanced now just keep rolling what the hell eastwood subduction of some sort of ocean plate giving us the inter-montane super terrain the twins and cash creek in between eastward subduction but here i'll show you a diagram in just a second with this guy that's recording an ocean trench out in the pacific at a fixed location and by moving north america closer and closer to that fixed trench out in the pacific we can eventually accrete the insular super terrain that's rangelia and alexander onto the windshield of our moving car this is different than the old store the old story says all these terrains are going to come and add to the edge of north america north america is moving west but we've got a moving ocean plate eastward in eastward subduction karn and mitch are saying no between 170 and maybe 80 million years ago and probably off a little bit on those dates but let's say roughly for a hundred million years we did not have eastward subduction of the fairlawn plate instead the ocean floor between intermontane and insular the ocean floor was connected to north america and the ocean floor was subducting into an ocean trench that was fixed in the pacific so we're still going to accrete the insular super terrain of course we are it's there we're going to accrete it 100 million years ago but we're going to create it by the windshield plowing through the baked potato the the the super baked potato as opposed to the opposite you're like you've lost me completely let me show you a diagram from my notes which is coming directly from some of karn's papers and then we'll back away just a bit fixed 170 million years ago the intermontane has already accreted has just accreted to old north america but this model says starting 170 we have westward subduction of an ocean floor that was connected to the north american continent not the old pacific the old fairlawn plate subducting the other way and notice we have our insular super terrain out here in the pacific you're like why is this a leap forward well we can prove where it was we can prove where it was because directly beneath where that insular used to be is a slab wall which is today the east coast slab wall but back then when north america was much further to the west when north america was much further to the east we had this thing started up as a fixed frozen yogurt flow by a hundred million years ago we have moved old north america substantially and we have consumed much of this ocean floor crust where did it go it's still it's down there it's still there we still have it it's just more stuff that we've added to the frozen yogurt cup and then by 75 million years ago we begin true eastward subduction of the farallon plate or coola plate but the point is we have eastward subduction so eastward subduction earlier than 170 eastward subduction younger than 75 that's the old story but between 170 and 75 roughly 100 million years there's a compelling case for westward subduction you say i don't buy it i don't believe it i don't buy it well how do you explain this thing then it's there how do you explain it angry suddenly i don't know why that was the heavy lifting portion i don't know where we are meaning i don't know where you are mentally i'll just try to flash forward a couple of things and then we'll go uh in the cozy fort after i read a couple emails so here's a technicolor version of what i was just trying to do with you this is from a brand new paper a paper that came out this year from one of caran students edward clinette so here's those same time frames with the old story and the new story and eldridge moores and others proposed kind of this archipelago idea out in the pacific off coast of north america but did not get much traction that without any knowledge of the lower mantle he had other reasons from the geology of ophiolites and other things that allowed him to visualize this the whole idea is we're actually just consuming a bunch of ocean basins like there's like more than 10 separate ocean basins that were between scraps of island arcs that that are gone but they're not gone they're either down in the lower mantle or parts of it got abducted uh on to the edge of north america we'll look at that in their north cascades and other places uh now i'm just like assuming we have a semblance of what this is so i'm just sharing this is all from edward clinettes let me get that paper for you so this is the the newest paper from karen's group and that animation i showed you last time and i'll show it again to you today is from from edward so i don't know i'll just do this quickly they've got the tomography stuff they've got the plate reconstructions here's north america with new york city that's me drawing that so i'm just going to do this quickly because we're already past the top of the hour you're like i don't know i can't see this can't you do an animation edward did and another one by henderson in 2014 also karen's former student remember the main goal here the main goal was to first of all let you know that there's a a brand new set of ideas that are in the face of the old ideas involving american west tectonics and therefore implication on how exotic terrains were accreted how they were accreted not when but how they were accreted using karn's geophysical work and mitch's encyclopedic knowledge of exotic terrains all up and down the west coast of north america what's this it was these guys that were uh and actually eldridge first came up with it but the idea that you can look at australia today and make a connection to what this archipelago thing would look like this is really clever i think this is edward's paper so you might just pause this and take a look at it but it's it's making comparisons between australia today north america back then and the idea that you're driving the continent into a bunch of baked potatoes that are fixed out there as opposed to the baked potatoes coming to you it's like how bad do you want the baked potatoes you're going to come get them because they're not coming to you and here's just one of the the images of the many images that show north america drifting west and first encountering that ocean trench at about 140 million years ago i'm doing the best i can for you man i understand this is challenging i'm gonna finish if i can find it by sharing a couple of the oh man i gotta find it now i've built it up well there's a brand new thing from karen who's replying to critics of her new work but i definitely have to find these emails give me a second would you hang on patrick there you go i'm having fun even though this is heavy lifting for me i didn't even check my notes uh give me a second yeah yeah oh just the shape of this maybe you're bothered by the reflection on the chalkboard i don't know i can't help you just the shape of that slab wall the shape looking down on this lab wall in the lower mantle is this shape right it doesn't mimic this coastline of north america like if you want to argue that this is old fairlawn that has subducted and now is underneath north america is almost coming out the other side by the way shouldn't it mimic the the shape of the trench it doesn't mimic it so instead this is a relic of the position of the ocean trenches that used to be west of north america i understand this is a challenge to visualize uh oh i feel like it before i get to the emails from karen and mitch let me so here's uh i don't know if you're aware but you have papers that are published everybody reads them in the little scientific world and then occasionally if you're sufficiently ticked off that's probably the wrong way to say it you publish a comment which is like a rebuttal this car in mitch 2020 you can read the whole thing if you want looks like this i'm not a confrontational guy but i kind of enjoy reading stuff like this pavlos published in 2019 assert that geological and geophysical inter interpretations lead to fundamentally different conclusions regarding the dipping of this abduction along the courtyard margin during the late mesozoic time their paper is a call to defend a model of uninterrupted eastward subduction beneath continental north america which we refer to as always andean style model from purportedly contradictory geophysical observations our own work this is karen and mitch shows that no such contradiction exists neither geology nor geophysics supports always andean style subduction since 200 million years ago instead both record a gero-cretaceous period of simulation uh simultaneous eastward and westward subduction under a vast archipelago in northeastern proto-pacific analogous to today's southwestern pacific welded into westward subducting lithosphere north america was pulled into the archipelago and diaconastly i can't pronounce that word over uh not at the same time overrode it from 155 to 50 million years ago accreting its arcs and micro continents whoa 50. oh celestia part of this uh i want to go on but i i'm we're we're running late so i promised i'd share a little bit of the email response that i got from karen and mitch because i think it adds a little personal uh touch to this so two weeks ago i sent individual emails to both karen and mitch i'd never met either of them they they have no idea who i am uh karen replies fan mail is a pleasure obviously our conclusions about rengelia in the archipelago don't meet with universal approval mitch it's always nice to receive fan mail thanks it turns out when you revive a half century old model from the formation of the north american courtyard because it is supported by new tomographic details most mail that once receives is not by supportive fans we've still got a lot to learn before we can readily or reliably read the mantle but the prospects of being able to do so are very exciting a big impediment is incomplete global coverage and difficulties in evaluating the reliability of tomographies that's the the deep mental stuff and especially in distinguishing between artifacts and real velocity structure a karen and mitch if if you eventually see this i hope you're okay with me sharing your your email i said to karen i'm doing a new session called karen siglock she said that's flattering but i'll just note that these investigations have been very very close collaborations with mitch maholinic who has a skill set that is very different and complementary to mine and who was prepared to invest the significant time we needed to develop a joined up way of thinking the crucial and challenging thing about this research is to understand the uncertainties inherent to the various disciplines involved and it's mitch who decided that because i couldn't on close re-inspection of geologic observations one could separate rangalia from the inter-montane super terrain for longer than usually asserted by the way if you're curious about the timing of this and i'll show you that segment of karen's talk in just a second in the cozy fort she has an average sinking rate of these slabs in the lower mantle of 10 millimeters per year i don't know where that comes from but she's done some math to figure out that there's a real steady uh sinking rate of 10 millimeters a year and therefore you can you can get these trenches uh located properly if you go back in time i asked mitch how did you connect with karen and are you still working with her this two weeks ago mitch says back around 2011 i was struggling to understand why a belt of massive molybdenum copper porphyry deposits like the climax the henderson the bingham sit so far inboard of the active continental margin it seemed like mantle tomography might provide some clues after scanning the literature looking for what i as a complete outsider to tomography would consider the best regional study i singled out karen's work i emailed her she was then at university of munich in late 2011 and we found out that our interests were highly complementary but we needed to figure out how to read the mantle first it was really exciting discovery laden work and by the end of 2012 we had cobbled together a paper in the journal called nature without having yet met each other in person my original question about linking the giant porphyrias with the mantle remains unanswered although it is part of a growing to-do list that we continue to collaborate on you may be interested in our most recent paper by edward uh clinette hey by the way this is mitch if you're speaking with your pal jerome lessman remember last show please pass along a hello his invitation to speak at viu geology department led to a very pleasant afternoon with super engaged students i was not expecting such informed inquiry inquiry from college students it clearly speaks to the motivational and educational skills of their instructor nice job jerome i'm going to do a little bit more i told you you should settle in i had a couple questions for karen and mitch and she says you ask very pertinent questions here and mitch said i don't usually share compliments but this is a big one for me so i'm going to share it hope you don't mind mitch who's got a long career in this game and is a high-powered thinker says to me obviously your content he's talking to me your content and own interests are cutting edge in your email you've asked the key question about how the mantle might inform us on the evolution of the mesozoic intermontane super terrain only a couple of other colleagues have bothered thank you i'm going to show you a clip from karen's 2014 talk and i i i asked both of these guys you don't have slabs in the lower mantle from the closure of the slide mountain or cache creek oceans do you guys have that now if yes does that change the jack night knife look of the intermontane the string bean current yes we have recently obtained much better resolution of deeper slabs and they are plentiful but we remain unsure what the correct interpretation is with respect to the older evolution of the cordial the first order observations are that there are there is abundant slab below the slabs we have been interpreting below 2000 kilometers depth but in quite different configurations meaning there would have been a predecessor archipelago to the archipelago that we have been interpreting above 1800 kilometers depth and between the two there was a considerable reorganization presumably the insular super terrain would have always shuffled around in this environ environment by the way she's got a lot of things she has to do and she took the time to to write this this wonderful email but that older archipelago should have been is archipelago or archipelago archipelago should have been as off far offshore pangaea as the younger one and that looks like a problem for explaining the native triassic jurassic arc in the southwest u.s while attached to pangaea which mix thinks of as linked up with the native ark that's maybe negotiable on the other hand there's a very deep slab under under the central atlantic in a suitable location to explain the native ark along western pangaea is anybody still with us but it's deeper than we expected okay well back and forth back and forth i'll finish with this there's still kharan we are currently most excited about the prospect of establishing an absolute reference frame that goes back 250 to 300 million years equivalent to the ages of the deepest slabs using slab piles and relatively confident geologic knowledge in completely different regions of pangaea so they're going other places now in the world they're not just sticking with western north america with this new technique this major effort will take a while but once we've convincingly established such a slab reference frame and shown its consistency with hot spots for the past 120 million years then we'll be in a much more solid position to return to address the older courtier and slabs i can't stop if the american slab walls had been imaged back in the 1970s i don't think the narrative of an always andean margin would have gained such traction eldridge moores used to say it was an example of a hypothesis that went right on to dogma skipping the intermediate testing stage though he had a funnier way of saying it okay we're just going into the cozy fort now and it's 10 20. we may be here till after 12 noon should have brought a sandwich if you're still with us congratulations we got almost 900 people that's great we're going in the cozy fort damn it it's worth it we've got a couple things to show you there you should meet karen through the magic of youtube and then why not we'll do some live q a with the guy who knows nothing about geophysics should be fun hot mike cozy fort by steve boy that was that was hard and there are parts of this that i think will will revisit i'm thinking out loud now i'm still trying to grasp some of the basic messages from this work especially how it impacts what we know about the north cascades let's say so i think we i might continue to try to use some of this in our remaining sessions into early december but i'm not quite sure how we're going to do that yet i'll also be very interested to see the reaction to this show like oh my god for the first time i was completely snowed over and i had no idea what you were talking about for half of it or that's all i don't know why you spent a whole period on that that's that's phony pseudoscience i don't know i'll be curious especially from fellow geologists and their reactions but but yours as well i hear a voice i don't know who it is i'm going to pretend they're not here okay oh it's a loud pedestrian i mentioned eldridge moore's back in the 1970s and 80s he came up with the idea among others somebody had the foresight to videotape him on a field trip in california this is on youtube um hang on uh let's start with a big picture i'll just say a couple of words about this but i didn't bring the map of the world okay so obviously this is the tectonic map of western north america and i think you can see the black blobs on the map uh those are ultramafic rocks and you can say in effect they're ophelia complexes of various ages we'll be talking about this one here in the klamaths is probably the oldest one on the western north american continent it goes back to the lake three cambrian the the rest of these are this one here is lower polyesteric and age down in the kawia belt down in here and then the rest of these are mostly jurassic mostly mesozoic grenades although there are some rocks over here in nevada that one could call ophelinic rocks and and i think in fact uh one can make an argument that there is another belt i just wanted you to meet him on youtube he passed away during a field trip by the way a handful of years ago and i always enjoyed listening to his talks at a gsa conference for instance i'd send him a fan letter by email and you if you're like i think i know that name eldridge moore well he was the main topic in assembling california written by john mcphee and so in addition to complimenting eldridge on his work just a few months before he passed away by the way i asked if i could get an email for john mcphee because i wanted to send him a fan letter he said oh he doesn't do email but here's his uh address mailing address so i heard from mcphee a little bit but eldridge had those concepts of the archipelago offshore even though he's kind of from the old guard he was thinking forward and it's too bad he's not able to enjoy some of this now karen uh the only youtube of her that i could find from a talk that was she was giving in barcelona in 2014. thank to toppo you this is a talk about continental growth in north america it's made possible largely because north america has been so well instrumented seismologically in the first place over the last decade but as a motivation for europe i might say these processes that i'm going to talk about here crustal growth in the mesozoic happened in europe like that in the paleozoic and maybe one day we will be able to reconstruct what happened in europe with the methods presented here okay i wanna it's a 30-minute talk the title of this you can find it on youtube uh barcelona 2014 topo europe continent ark collisions maybe somebody can put the link down below uh so it's a 33-minute talk and i think i've watched it 10 times taking all sorts of notes and it was just so gripping the way she laid it out in such plain english but i i want to let's see let me let me find the sinking part because i don't understand that very well we'll start here hope it that works this might be plausible so these might be older than we thought and these might have been built by trenches that were intra-oceanic rather than along the coast here and because they were intra-oceanic they could sit stationary in the ocean and they didn't have to migrate as a trench along this coast would have migrated as we know the continent migrated so the prediction that needs to be tested here then is these were long lived stationary trenches that sit here set here in the jurassic and um subducted in this direction because there was this open ocean between pangaea and these trenches and and they were made from from the plate the tectonic plate that subducted into here as north america would come in and override these trenches and any arcs and other oceanic material accumulated above them so as a as a cartoon this would like would look like this in the jurassic we have a trench sitting here in the ocean and it can fit stationary in fact it's probably it's probably stabilized by the slab once this is in the lower mantle it's quite inert and it'll it'll it won't move back and forth it'll just sink so it'll sink vertically and as this ocean closes here and north america moves in the slab gets deposited this also makes a prediction of what happens next so this one we just saw this is while this trench and arc are active but at some point this ocean has closed and this is shown here and then this subduction must stop meaning it stops building the slab wall we get this sharp upward truncation which we did see under canada i pointed that out and it also means this arc now stops so there should be a date on this and what happens next though i could go on but i think america kept moving i'm now at the latest now you can watch that on your own uh there's also an amazing website oh the wind's picking up i'm gonna lose everything uh atlas of the underworld that's a great spot great title uh so there's there's tons to learn and absorb from that website uh what else do i have a couple other things before we go to the cozy fort i've shown this forever in my classes i think it's tonya atwater's original uh uh animation it's kind of soothing i put it on a loop this is eastward subduction of the farallon beneath the west coast of north america which i want to re re-iterate is totally accurate younger than well more recently than our topic today but during the insular super terrain i don't see the geology evidence and i think there's been always some issues always some kind of problems with the geologic evidence in the north american continent to support a long standing eastward subduction of the fairlawn plate by the way karen's talk includes some question and answer at the end in that 2014 talk and there's a couple of dudes who are basically pushing back and saying you know this there's no way so she's faced a lot of uh that's the way science works especially if you're trying to do something drastic oh this might be fun okay i think i do have a request now so with this one can you kind of hold the dish steady underneath the chocolate and just kind of let it uh just kind of let it kind of get constantly and it'll just kind of she was a good sport i tried not to be creepy about it i'm a teacher i i'm a geologist i'd like to videotape you it's like whatever dude we can't have this session in the cozy fort without showing you one more time what i showed you the last couple's programs this is current student edward came out this year orange is insular purple is intermontane but if you look carefully at the teeth there's eastward and westward subduction on both sides of the insular for a while and then again there's something called baja bc which does work with this new set of ideas and if you don't know what i'm talking about with baja bc you'll have to wait but um we can lump merle and a bunch of baja bc people in with the new set of ideas and the tomography the lower mantle is helping to confirm some of those ideas as well basically i'm trying to show you north america coming to the orange as opposed to the orange being brought in by a simple large fairlawn plate and i think ivana who i see is here again ivana might have a link i kind of forgot ivana could you put the link to that henderson thing that you stitch is that on a youtube channel that you have could you link that to everybody uh which i don't have handy right here okay that's enough that's enough god all right so still have more than 800 people it's time for some live q a this ought to be good thank you for being with us for this marathon session it's only the beginning i think of totally grasping what we're talking about here today but we won't have you know five more car in sessions so this will have to be it for a while oh man i'm down to 20 battery in my laptop but that's another reason to quit okay let me let me find us here uh pop the live chat out like a boss and uh try to answer a few questions valerie at 10 34 that's one minute ago we'll keep going back to that animation man somebody said they really like the animation show it again i've already shown it twice but we'll again maybe ivana can help us find some of that valerie if the mantle remains as ribbon candy in the core does it cool the core i'm going to know very little about how to answer these these lower mental questions but i don't see how that would even though their huge slab curtains valerie i don't see how that would affect or help cool the core you're aware that there's a liquid outer core and a even hotter uh solid inner core but i don't think we know how to answer that but i i don't see an obvious way to do that or an effect on the core eric do you know what the original longitude of the eastern slab wall that's a good question i don't off the top of my head let's see we're in ellensburg we're at 120 degrees west longitude i guess maybe there's longitude on one of those maps i mean there's the 2013 so karen's got a research record i'm not going to grab all the papers that i printed out but basically her first major effort was in 2007 or 2008 with her jeep with her i don't even know what i'm talking about with her 3d tomography stuff and then the real bomb in the marketplace was the 2013 paper where she and mitch are laying this out for the first time to a general audience and i don't still have a good sense of if that was just largely ignored or people were absolutely ticked off immediately but that was kind of in the face of the native ark business and so they kind of as i understand it in 2017 another major paper talking about a suture mitch and karen uh incorporated the native ark into the story so that there's plenty of eastward subduction both before and after this westward subduction story that's the centerpiece of the discussion why did i get into that oh maybe some of those maps have longitude like pure longitude of that insular arc as it was fixed but i'm not sure that oh the breeze picking up when it's 31 freaking degrees it's too early for this gary i thought both sea floor and continental plates both floated on upper mantle uh yes gary tectonic plates are rarely simply just ocean plate or continental crust there's combinations of both in the case of this discussion there are plenty of ocean plates that are small and 100 ocean crust and again we're crunching or destroying or both many of these former ocean basins which is a real mind bender as as uh jerome is fond of saying uh so yes we have these lithospheric plates that are riding on top of stenosphere which is down below tough enough does the coriolis effect play in somehow i don't see how ats how do hot spots interact or not with subducted slabs well to be honest ats thank you for the question it feels like this tomography stuff kind of came out of nowhere independent of karen's work like people just were suddenly like jeff tepper and others were suddenly talking about this slab curtain underneath idaho like what are you talking about they're like we had this us array for the last 15 years where have you been man talking to me it's like we've got we know some stuff underneath and we're trying to figure out if it's subducted cooler or fairline or something else and and that dealt with slab windows and slab roll back and other things that i was just starting to wrap my mind around which is a more recent story so i don't know how many 20 25 of you 30 of you emailed me low power mode oh crap are you still i'm on low power mode on my camera are you still here so i gotta i gotta wrap up soon um many of you emailed about the the uh article on the resurrection plate thank you for that that's tomography as well but we're not talking about the resurrection plate here today or the cooler plate or some of these other younger diving plates that's a story related more to the chalice magmas and other things that i was kind of focusing on until this summer and now i'm into this older time frame eventually i'll get back to the chalice story and talk about resurrection etc so i don't know how to answer your question about hot spots interacting except to say that according to carn type folks hot spots are real hot spots are fixed now we're realizing these slab walls are fixed and it's a question of how a drifting plate over a hot spot is too much for my brain at the moment thanks for the question i'm scrolling down to live because i only have a few more minutes left uh doug seems like another j harlan brett's level of acceptance of new ideas hopefully this will be better that's interesting doug you remember the baja bc thing which we haven't even discussed yet was really marginalized and still is marginalized by most mainstream geologists who just don't understand the details of the paleo mag world i fear it's the same story here i don't understand how they're getting all this data from the lower mantle so therefore i'm just going to say it's it's baloney uh and j.r harlan brett's is a different kettle of fish but um yeah the history of science is full of this right if you have the data you got to have the data you can't just have the idea you can't just have an idea many i i see here have the wonderful against the grain ideas you've got to be a trained scientist to actually collect the data and current is one of the best as i understand it you've got to have the data to start but then if you have the data and it's robust and it's long lasting and it's combined with an old school bedrock guy and they have a coherent story and you're still just saying it's all a bunch of bologna then i think you got to look in the mirror uh a couple more dutchman but why if ocean floor floats because of being less dense i suppose why can't it sink i don't know the context of that bob why are the subducting plates not melting into the mantle too much pressure yes that's the easiest way to visualize it from my point of view it's hotter as you go deeper but the pressures also increase and so there's some some phase situations there uh i'm scrolling back now man it's cold out here i'm whining now julia sinking curtain encounters something to stop its sinking action and curtain above continues to sink and bends back on itself my question is what does it hit that makes it stop sinking i have the same question karen where'd the apple go i can't find the hat the half of the apple that have my little things in but karen's main slab i think is between one thousand and two thousand kilometers down and two thousand is not the base of the lower mantle so i'm a little fuzzy julia like you are on are we really sinking the the frozen yogurt is it piling up on the true base of the mantle or do they not have the resolution that far but is that the thought that we're getting all the way down to the the core but then the outer core is liquid so why is it piling up on a liquid i don't know that maybe somebody does here this is too fun couple more i see why i'm getting cold the sun's going behind another tree uh smiling llamas asks what happens at the junction to make the switch from east to west subduction that's a great question that's how we'll finish i don't know how to do it i'll just do it verbally maybe with my hands so if insular is here remember it's fixed and we've got our our frozen yogurt uh piling up underneath this is the insular or angelian alexander it's out at some specific longitude out in the pacific and here comes is this right for you this is correct isn't it i'm looking at it backwards here comes north america and we're doing westward subduction uh with this ocean floor connected to my hand right and then eventually now insular is accreted 100 million years ago and now i'm going to move it back i'm going to start again so here's insular right here in the frame here comes north america with ocean uh crust connected to it we're subducting you got it westward subduction westward subduction westward we closed the ocean boom 100 million years ago now insulur is accreted with western north america and it's it's hooked on to north america now and there is the beginning of the subduction eastward of the fairlawn plate that's my current understanding of what we're talking about okay i got to go inside and warm up and a toast to you suppose my hot water is cold here's to you for sticking to the end of what has to be the longest live stream that we've done since st patrick's day here's to karen and mitch and many other scientists through the history of science who compile amazing sets of data and have the courage to present it even though it's probably ugly in the short term with the old guard clinging to their lifelong views here's to us regular folks trying to make sense of complicated material and if presented properly is possibly digestible and of course here's to your health the health of your parents and your grandparents the health of your children and your grandchildren everyone in your family everyone in your community uh i think it's official the next time i see you it will be friday whatever date that is this coming friday at 2 p.m pacific time we're going to the san juan islands we're returning to bedrock we're returning to field data we're returning to our story but a little sneak peek the san juans and many of the terrains within the north cascades are the result of colliding north america with the insular super terrain it's stuff that got caught between north america and the insular super terrain that's why we did this show before we went to the north cascades hopefully it worked thank you for joining us i love you and goodbye lower mantle tastes great less filling tastes great this episode of nick from home brought to you by utopia frozen yogurt right across university way from the campus of central washington university goodbye

Channel: Nick Zentner

Views: 16,909

Rating: 4.9825897 out of 5

Keywords: Nick Zentner, Karin Sigloch, Exotic Terranes, Tomography, Tomotectonics

Id: PeOjwZfb704

Length: 124min 58sec (7498 seconds)

Published: Sun Oct 25 2020