Latest / PlanetGeo: The Geology Podcast / The Length of Day 2.5 Billion Years Ago - BIFs, Milankovitch, and Geochron with Dr. Josh Davies

Transcript

The Length of Day 2.5 Billion Years Ago - BIFs, Milankovitch, and Geochron with Dr. Josh Davies · PlanetGeo: The Geology Podcast

• 0:00
  SPEAKER_00: Hey folks, I'm really excited about this interview.
• 0:02
  SPEAKER_00: We got to talk to Professor Josh Davies.
• 0:04
  SPEAKER_00: Josh and I go way back.
• 0:06
  SPEAKER_00: We were graduate students together at the University of Alberta, and he actually kind of taught me the ropes, showed me the ropes of geochronology.
• 0:11
  SPEAKER_00: He is a really high precision geochronologist, runs a lab at the University of Quebec at Montreal, and really applies, he has an amazing publication record because he applies this tool that is in the toolkit of a modern geologist to amazingly important problems and amazingly cool scientific stories.
• 0:28
  SPEAKER_00: And the one we focus on today is a project that they've been working on where they use banded iron formations to go back 2.5 billion years ago, determine how long it took those banded iron formations to be deposited, and then look at Milankovich cycles in those banded iron formations and use that information to calculate the distance between the Earth and the Moon and even the length of the day 2.5 billion years ago.
• 0:51
  SPEAKER_00: So it's an amazing story.
• 0:52
  SPEAKER_00: Can't wait for you to hear it.
• 0:54
  SPEAKER_00: A quick note due to scheduling conflicts, Chris was not able to join us.
• 0:57
  SPEAKER_00: So you're just getting me and Josh.
• 0:59
  SPEAKER_00: We go way back, so I hope it's it's still interesting to you.
• 1:02
  SPEAKER_00: You can expect to be hearing more from Josh, I think, in the new year.
• 1:05
  SPEAKER_00: We've got some uh some plans to do a deep dive into geochronology, a grid geochronology series.
• 1:09
  SPEAKER_00: And so you can expect to probably hear more from him coming in the new year.
• 1:13
  SPEAKER_00: You can follow us on all the social medias.
• 1:15
  SPEAKER_00: We're at Planet Geocast.
• 1:16
  SPEAKER_00: Shoot us an email.
• 1:17
  SPEAKER_00: There's a contact us link at our website, planetgeocast.com.
• 1:20
  SPEAKER_00: And if you want to learn more about the geosciences, head over to our Camp Geomobile app.
• 1:23
  SPEAKER_00: First link in your show notes.
• 1:24
  SPEAKER_00: We have the full introduction to the geosciences, that course in an audio textbook version on the app, as well as some other stuff on the geology of the Grand Tetons, the Grand the Grand Canyon, um, Yellowstone National Park, and all sorts of other stuff that you can check out there.
• 1:40
  SPEAKER_00: So click on that link and check it out.
• 1:42
  SPEAKER_00: Let us know what you think.
• 1:43
  SPEAKER_00: All right, Josh Davies coming at you.
• 1:45
  SPEAKER_00: Let's uh let's dive in.
• 1:47
  SPEAKER_00: Welcome to Bun of Hido, Professor Josh Davies.
• 1:50
  SPEAKER_00: Um, we're gonna talk about a whole bunch of stuff, but you and I you and I go way back.
• 1:55
  SPEAKER_00: Um, we've been friends since graduate school, colleagues, collaborators, even on a bunch of different projects.
• 2:00
  SPEAKER_00: I would say we we did.
• 2:02
  SPEAKER_00: We live well, you lived in the basement.
• 2:04
  SPEAKER_00: You were a basement dweller, and uh we lived in the upstairs.
• 2:07
  SPEAKER_00: The rest of us normal people lived in the upstairs part of the house.
• 2:11
  SPEAKER_00: But um we we we go way back.
• 2:14
  SPEAKER_00: What what would you qualify me as?
• 2:16
  SPEAKER_00: Uh colleague, collaborator?
• 2:18
  SPEAKER_00: Well, I would hope a friend.
• 2:20
  SPEAKER_00: I would say more friends.
• 2:23
  SPEAKER_00: More friend, okay.
• 2:25
  SPEAKER_00: That's good.
• 2:25
  SPEAKER_00: That's good.
• 2:26
  SPEAKER_00: Uh uh but uh but uh quite a quite a wedding attendee.
• 2:30
  SPEAKER_02: I think I think you were actually I mean, considering our wedding was only parents and one person invited from my side and one from my wife, you were the one who were 100% of the the congregation from my side.
• 2:43
  SPEAKER_00: That's pretty good.
• 2:44
  SPEAKER_00: I was the witness, the singular witness.
• 2:46
  SPEAKER_00: There's no actually no other witnesses.
• 2:48
  SPEAKER_00: No, that was it.
• 2:49
  SPEAKER_00: That was it.
• 2:50
  SPEAKER_00: So I mean quite an important person, I would say.
• 2:52
  SPEAKER_00: I would say so.
• 2:53
  SPEAKER_00: I would say so.
• 2:54
  SPEAKER_00: Um okay, so this is published quite a lot of papers, I think.
• 2:58
  SPEAKER_00: We we have published together that uh you are probably my most either first or second most prolific co-author or most common co-author, apart from my PhD supervisor, Tom Chaco.
• 3:08
  SPEAKER_00: So I think you and I might have have have more papers together these days.
• 3:12
  SPEAKER_00: But well, okay, I I want I I'm actually gonna ask you some questions that I don't know the answer to, kind of personal questions, about how you got into geology.
• 3:18
  SPEAKER_00: I I don't think we've talked about some of this stuff before, but I really want to talk about stuff that I am not related to, the science stuff that you've been doing over the past couple years or the the last maybe five, eight years that I'm not involved in, and I'm really not too familiar with, apart from reading some of the papers and talking about it with you when we see each other occasionally at conferences and things like that.
• 3:40
  SPEAKER_00: So we're gonna start out with the with the normal kind of planet geo style of questions here.
• 3:44
  SPEAKER_00: I'm curious, Josh, because I think I know you I think we have a similar backstory here to how we got into geology or at least the time in our lives.
• 3:51
  SPEAKER_00: But could you describe what got you into geoscience and you know whether there was sort of an aha light bulb moment for you and in your early career trajectory, I guess?
• 4:01
  SPEAKER_02: Well, I think actually for me, I started actually learning about geoscience a bit earlier than you.
• 4:08
  SPEAKER_02: Because I had courses in in school, in high school or secondary school, because I'm from the UK.
• 4:15
  SPEAKER_02: Um, and so yeah, I actually took an A-Lab.
• 4:18
  SPEAKER_02: I couldn't tell.
• 4:18
  SPEAKER_02: I didn't know you were from the UK.
• 4:19
  SPEAKER_02: That's really interesting.
• 4:20
  SPEAKER_02: You couldn't.
• 4:24
  SPEAKER_00: That's right.
• 4:24
  SPEAKER_00: It's all gone away living in Canada.
• 4:26
  SPEAKER_00: It's gone.
• 4:26
  SPEAKER_00: Yeah.
• 4:27
  SPEAKER_00: Of course.
• 4:29
  SPEAKER_00: So what what what grade level was this then?
• 4:31
  SPEAKER_00: Or equ you know, equivalent age.
• 4:33
  SPEAKER_02: The last two years of school before university.
• 4:36
  SPEAKER_02: So I don't know what w what's that.
• 4:38
  SPEAKER_00: Junior senior of high school equivalent for American uh and Canadian standards, yeah.
• 4:42
  SPEAKER_00: Yeah.
• 4:43
  SPEAKER_02: So like in the UK, that time you kind of really specialise and you kind of I mean, I took four uh courses.
• 4:50
  SPEAKER_02: I mean, I only did four subjects at that time, and one of them was geology, because we had uh like two science teachers at school.
• 4:59
  SPEAKER_02: Well no, the school had a load of science teachers, but there was two science teachers that actually had degrees in geology, one had a PhD, the other one had a master's, I think.
• 5:07
  SPEAKER_02: Wow, that's incredible.
• 5:08
  SPEAKER_02: What one had a PhD in geology.
• 5:11
  SPEAKER_02: Yeah, yeah, yeah.
• 5:12
  SPEAKER_02: Yeah, yeah, yeah.
• 5:12
  SPEAKER_02: I'm crazy.
• 5:14
  SPEAKER_02: So they actually just they like geology themselves, and they I mean, and I was like into kayaking.
• 5:19
  SPEAKER_02: Actually, I still like kayaking, and one of them was a kayaker in my little kayak group, and he kind of spoke to a few of the students, and he was like, Oh, if there's some interest, um we me and the other teacher are gonna put on an A level for geology if you want.
• 5:37
  SPEAKER_02: Oh, right.
• 5:37
  SPEAKER_02: So they just kind of started a geology A level, and I was like, Yeah, yeah, why not?
• 5:43
  SPEAKER_02: Because I knew the guy from kayaking, I knew the teacher, and he was really nice, and I I knew the other one from because he was a chemistry teacher, and so actually I took geology at high school at the like the end of high school, and we're and actual honest to honest to goodness, geology.
• 5:59
  SPEAKER_00: They were your not geoscience, not earth science, but geology, no, no proper geology, like proper geology, and interesting.
• 6:06
  SPEAKER_02: And we did a field trip.
• 6:07
  SPEAKER_02: Um, because I mean I was grew up in Wales, and so we did a field trip to Scotland, to the island of Aaron.
• 6:13
  SPEAKER_02: It's actually a really cool little island.
• 6:15
  SPEAKER_02: There's a massive granite intrusion, and so there's these sediments that kind of touch up against the granitic intrusion.
• 6:22
  SPEAKER_00: Is the uh is is is Aaron the one of the the the islands on the west side of Scotland, like with the the the the the weird one with the funny cats on it and uh the the other those other islands, the whiskey drinking country that we visited at one point, or is is that different?
• 6:36
  SPEAKER_02: Aran Aaron does have whiskey.
• 6:38
  SPEAKER_02: I think it's got one uh distillery called the Aaron Distillery.
• 6:41
  SPEAKER_02: It is on the west coast.
• 6:43
  SPEAKER_02: It's the west coast, okay.
• 6:44
  SPEAKER_00: Yeah, it's not as far north as Sky, but but not as far south or out outer inner head breeze like Isla or anything like that.
• 6:50
  SPEAKER_02: Okay, gotcha.
• 6:51
  SPEAKER_02: It's it's yeah, it's kind of in the middle, I guess.
• 6:54
  SPEAKER_02: Okay, gotcha.
• 6:55
  SPEAKER_02: But it's it's kind of I mean when we were we were high school students, we went there and we saw kind of like we could put our finger on the contact between uh like a big massive granitic intrusion and like the sediments that it was touching.
• 7:08
  SPEAKER_02: You could see like a hornsfell zone, and like it was really, really cool.
• 7:12
  SPEAKER_02: You saw the minerals changing kind of further away from the granite, and it was really cool.
• 7:17
  SPEAKER_02: Also, like we just we just spent time outside, you know, in Scotland it's really beautiful.
• 7:23
  SPEAKER_02: Uh I just had a really great time.
• 7:24
  SPEAKER_02: Yeah, and the other things I like.
• 7:26
  SPEAKER_00: Okay, that that set the stage for for univers.
• 7:28
  SPEAKER_00: So you went to university knowing you wanted to be in in geology, geoscience.
• 7:33
  SPEAKER_02: Well, in the UK again, I mean it's I guess it's different from the US.
• 7:37
  SPEAKER_02: I went to university to study geology.
• 7:40
  SPEAKER_02: So actually, I mean I after doing that course, I chose geology for university.
• 7:47
  SPEAKER_02: And that's what I did.
• 7:48
  SPEAKER_02: I mean, I did some like chemistry and some other courses, but my main stuff was geology.
• 7:53
  SPEAKER_02: And it's not common in the UK to have a A-level in geology.
• 7:58
  SPEAKER_02: So actually, it was it was it was good and bad.
• 8:01
  SPEAKER_02: My first year, I'd basically already done it all.
• 8:04
  SPEAKER_02: Um so I felt really cocky and confident, you know.
• 8:08
  SPEAKER_02: Well, that's where your natural arrogance comes from.
• 8:10
  SPEAKER_00: It's from A-level geology.
• 8:13
  unknown: That's it.
• 8:13
  SPEAKER_00: It's all from that.
• 8:14
  SPEAKER_00: It's all stems from that.
• 8:16
  SPEAKER_00: It's just it's just, I mean, I've never that's been my peak in geology.
• 8:20
  SPEAKER_00: I think that's what people say about you, is a real arrogant guy.
• 8:23
  SPEAKER_00: I mean, Josh did downhill from A.
• 8:25
  SPEAKER_00: It's been downhill since there.
• 8:27
  SPEAKER_00: I mean, that's it's actually, you know, that maps perfectly onto my experience as well.
• 8:31
  SPEAKER_00: Uh CRISPO has you know taught an AP, what you know, A-level would be AP, I think is kind of the the sort of pseudo-equivalent here, college-level geology.
• 8:40
  SPEAKER_00: And there's very few.
• 8:41
  SPEAKER_00: That's a very uncommon thing.
• 8:43
  SPEAKER_00: And actually, I just learned the other day in the state of Pennsylvania that earth science, even more general earth science, is not required at the high school level in the state of Pennsylvania, which is we were we were lamenting that fact because Pennsylvania has, I mean, resources matter a lot to this state and um natural resources, and to not have that.
• 9:01
  SPEAKER_00: So, anyway, uh having the advanced geology is really rare.
• 9:05
  SPEAKER_02: I mean, there's a subperiod of the Carboniferous named after Pennsylvania because of its oil, because of its coal.
• 9:12
  SPEAKER_00: Yeah, exactly.
• 9:13
  SPEAKER_00: Because of the coal, first oil well ever drilled.
• 9:15
  SPEAKER_00: I mean, you know, the shale gas boom was here.
• 9:18
  SPEAKER_00: I mean, everything.
• 9:19
  SPEAKER_00: So, um, anyway, uh so so from there, you know, it's just geology straight out straight away at Durham, right?
• 9:26
  SPEAKER_00: For undergrad at university.
• 9:28
  SPEAKER_00: And then the transition to graduate school in Alberta, where we met, you did a master's and a PhD in Alberta uh in geochronology.
• 9:36
  SPEAKER_00: And you really you taught me the basics of geochronology because you were a gra you were one year ahead of me in the graduate program, and I did not have a large lab group, like my PhD supervisor.
• 9:46
  SPEAKER_00: I was the only student for for much of the time in my my my supervisor's group, I guess.
• 9:51
  SPEAKER_00: It was like a one-person group, and you were much the same.
• 9:54
  SPEAKER_02: I mean, uh maybe not the only one, but well, actually, when I arrived, let me think.
• 10:00
  SPEAKER_02: For my PhD, my supervisor was kind of known to have big groups, um, but it was basically right at the end.
• 10:09
  SPEAKER_02: But I mean he didn't retire after I left, but he he retired, I mean, uh like a few years after I left.
• 10:14
  SPEAKER_02: Yeah, yeah, yeah.
• 10:15
  SPEAKER_02: But he was definitely winding down, and so I was his basically his only PhD student, and there was maybe there was a couple of people just finishing, but I mean it was just me, and there was a couple of master's students that came through at the same time.
• 10:29
  SPEAKER_02: But I mean, before he had big groups, and so he was like a big name in the department, but then it was me and you as the kind of hard rock.
• 10:37
  SPEAKER_02: We were kind of the surface geologists.
• 10:40
  SPEAKER_00: Yeah, yeah, that's right.
• 10:41
  SPEAKER_00: We were doing the the old rock stuff, and then you we went the we've been in the field together a whole bunch.
• 10:45
  SPEAKER_00: Anyway, to to to sort of tidy off a bit of your career story, you you went to did a postdoc at the University of Geneva, um, another spectacular, well-known geochronology lab, cutting edge geochronology, and now you've built your own lab at the University of Quebec at Montreal.
• 10:59
  SPEAKER_00: Um, and are well, maybe not built your own lab, but you you have have um been doing really high precision geochronology there for uh you brought high precision, really high precision geochronology there.
• 11:09
  SPEAKER_02: Um and you Yeah, that's kind of my specialty, I suppose.
• 11:13
  SPEAKER_00: Yeah, that's right.
• 11:14
  SPEAKER_00: So I I mean and for the listener, we're we're gonna have our plan is in the new year to you and I do some real deep dives into geochronology.
• 11:22
  SPEAKER_00: Like how how, you know, what does it actually look like?
• 11:24
  SPEAKER_00: What are the different ways we do geochronology?
• 11:26
  SPEAKER_00: What does it look like to do the work?
• 11:28
  SPEAKER_00: And I I'm excited about talking about that we with you because we've talked about geochronology ad nauseum over the years um over over many beers talking about rocks and and and dates of rocks.
• 11:39
  SPEAKER_00: Well, I would be surprised if zircon wasn't your favorite mineral.
• 11:42
  SPEAKER_00: It is it it is my favorite mineral.
• 11:44
  SPEAKER_00: I actually just gave a talk yesterday uh about uh some crazy zircons that uh I probably haven't talked to you about these yet, but um hydrothermal zircons, and I I told the story of when my wife asked me what my favorite mineral was, and I had to ask, well, for science or for fun, and she looked at me like I was an idiot.
• 12:01
  SPEAKER_00: Like, what what kind of a what kind of a qualifier is that?
• 12:04
  SPEAKER_00: Why do you need that qualifier?
• 12:05
  SPEAKER_00: But yes, for science, zircon is uh definitely my favorite mineral.
• 12:10
  SPEAKER_00: As is yours, probably, right?
• 12:12
  SPEAKER_00: Or or does badly eye still hold a or badly eye?
• 12:16
  SPEAKER_02: I mean, I do like badly eye, I have to say.
• 12:17
  SPEAKER_02: I really I like it.
• 12:19
  SPEAKER_00: I mean you like the problem, you like the tough stuff, right?
• 12:23
  SPEAKER_00: Yeah, I mean you like me.
• 12:24
  SPEAKER_00: If it's if it's easy, it's boring.
• 12:26
  SPEAKER_00: I mean, that's the that's the thing.
• 12:27
  SPEAKER_00: It's it's uh you it's gotta be complicated to make it fun.
• 12:30
  SPEAKER_00: Um, okay, so you are a dure chronologist by trade.
• 12:34
  SPEAKER_00: Um, and we we will get into way more detail about that uh in future episodes here talking about this.
• 12:40
  SPEAKER_00: But you are um one of the you you have an amazing publication record.
• 12:45
  SPEAKER_00: And I've I've told you this before, but you you have a very, very impressive publication record, and I think just reading through the list of papers that you have been you have published or you've been a part of kind of showcases the value of this deep geochronological toolkit.
• 13:00
  SPEAKER_00: Like you you have a tool in the toolbox that you're really good at, and your publication record showcases how many different problems this can be applied to in geoscience.
• 13:11
  SPEAKER_00: And I want to focus today, if if we could keep our conversation focused, Josh, uh that to one of them.
• 13:19
  SPEAKER_00: I want to focus on one of them, which is um calibrating the Earth-Moon distance back in geologic time, which I know is probably too deep for a single podcast episode, a single sort of 45 minute to hour discussion, but I want to try it.
• 13:34
  SPEAKER_00: So maybe we can like sideline you know how we do the measurements later, but will you just highlight for us and for the listener what the level of precision, when you say a very precise measurement, what does that mean?
• 13:47
  SPEAKER_00: Like what does a data point mean to you?
• 13:50
  SPEAKER_00: What's a what's a good data point?
• 13:52
  SPEAKER_02: I guess we we normally talk about precision in in in for for uranium-led geochronology, which is kind of my specialty, and also yours, partially yours as well, Jesse.
• 14:02
  SPEAKER_02: Um we talk about it in a percentage of the age.
• 14:08
  SPEAKER_02: Essentially.
• 14:09
  SPEAKER_02: So that's an easy way to think about it.
• 14:12
  SPEAKER_02: So that would mean if you speak about it as a percentage of the age, the absolute precision then is going to change depending on what the age is.
• 14:23
  SPEAKER_02: So if you have an age of three billion years, a zircon three billion years ago, and you date that zircon to a precision of a hundred thousand years, that is super good.
• 14:35
  SPEAKER_02: I mean, it's really, really precise.
• 14:38
  SPEAKER_00: I think just say those numbers again because that I I I we have to say that twice.
• 14:43
  SPEAKER_02: Yeah, we need to think about the orders of magnitude difference between the real age and the precision there.
• 14:48
  SPEAKER_02: I mean, yeah, three billion years, that's three with nine zeros on it.
• 14:53
  SPEAKER_02: And then the age of the the precision on that age could be one hundred thousand, uh, which is a one with five.
• 15:02
  SPEAKER_02: It's incredible.
• 15:03
  SPEAKER_02: It's incredible.
• 15:04
  SPEAKER_02: I mean, uh yeah, completely crazy in terms of precision relative to the age.
• 15:09
  SPEAKER_02: That's the one.
• 15:10
  SPEAKER_02: So in terms of a percent.
• 15:11
  SPEAKER_02: That's the best you can get.
• 15:13
  SPEAKER_00: The best you can get.
• 15:13
  SPEAKER_00: So in terms of a percent we are dealing with, I always struggle with this math.
• 15:17
  SPEAKER_00: It's 0.01% or 0.1% of the age.
• 15:22
  SPEAKER_00: 0.01% of the age is the uncertainty.
• 15:25
  SPEAKER_00: So that's that's the level something that's uh possibly achievable.
• 15:29
  SPEAKER_02: I mean, um we recently publ I mean we're we're again we're we're we're we're moving quite away from Earth-Moon stuff.
• 15:37
  SPEAKER_02: I don't know if that's a problem, but I mean uh so we recently published a paper.
• 15:42
  SPEAKER_02: Um a group of like the the geochronology labs, I mean, uh around the world.
• 15:47
  SPEAKER_02: So I mean there's a few there's a few labs in different places around the world that do these kind of measurements.
• 15:53
  SPEAKER_02: There's not that many, actually, but there was a uh a recent kind of um attempt to see that if uh the s the same lab is given exactly the same material, if if uh all these different labs are given the same material, what kind of precision can they get?
• 16:10
  SPEAKER_02: And uh does it all match up?
• 16:13
  SPEAKER_02: And so essentially this is using uh some uh like a solution, so something that can be homogenized.
• 16:21
  SPEAKER_02: So every single lab has a uh a solution of exactly the same composition.
• 16:26
  SPEAKER_02: You measure them, um and the age of the solution was uh I think 337 million years.
• 16:34
  SPEAKER_02: Okay, yeah.
• 16:34
  SPEAKER_02: Okay, so a million rather than a billion.
• 16:37
  SPEAKER_02: So that's like a um three orders of magnitude younger, but still quite old, I suppose.
• 16:43
  SPEAKER_02: Um and so it's a bit old, yeah.
• 16:45
  SPEAKER_02: Yeah.
• 16:46
  SPEAKER_02: Yeah, um, compared to us, I guess it's quite old.
• 16:48
  SPEAKER_02: Um so the labs essentially are very, very similar, not not at the zero uh at the zero point one percent level, it's at the zero uh point zero five percent.
• 17:04
  SPEAKER_02: Oh, yeah.
• 17:05
  SPEAKER_02: That's where you get that's where you get the overlap.
• 17:07
  SPEAKER_02: Okay.
• 17:07
  SPEAKER_02: Um but still, I mean, that's for all high precision, yeah, all of the high precision geochronology.
• 17:14
  SPEAKER_00: The high precision, and basically you know, for the listener, what we're talking about here it's uh functionally is I've talked about in in our lab we do geochronology, but we do it at the 2% level.
• 17:24
  SPEAKER_00: So if we have a rock that's a hundred million years old, the uncertainties on our ages are two million years basically.
• 17:29
  SPEAKER_00: And we can't do better than that.
• 17:30
  SPEAKER_00: And that two percent comes, we use a laser ablation instrument, so we uh we put little laser holes in parts of a mineral grain, and you do this stuff in your lab too, Josh, but but you focus more on um high precision work, which is dissolving the entire grain.
• 17:45
  SPEAKER_00: You do chemical treatments to optimize the grain, but you you dissolve the entire grain and then do a a different uh mass spectrometry technique where you you ionize all that uranium and lead and get a much more precise measurement rather than putting a little tiny laser hole in a in a zircon grain.
• 18:00
  SPEAKER_00: So, but this interlab comparison is really the important thing because it tells us that, hey, a bunch of labs around the world doing kind of the same techniques are giving roughly the same answers.
• 18:10
  SPEAKER_00: And what and that roughly is what we're trying to quantify.
• 18:13
  SPEAKER_00: What does roughly mean?
• 18:14
  SPEAKER_00: And for us it's 2%.
• 18:15
  SPEAKER_00: For you, it's what'd you say, 0.05%?
• 18:17
  SPEAKER_00: So far more precise.
• 18:20
  SPEAKER_00: Um, and what this means is you're dissolving individual zircon grains to get an age and multiple grains from a single rock to get the age of that rock.
• 18:29
  SPEAKER_00: Um, and what I find really impressive, just one last statistic about this, then we can get into some some Earth-Moon distance stuff, is that your individual uncertainties, your data points that you measure, the the data point and the uncertainty around that data point, often falls within the uncertainty that we as the community understand to be the uranium decay constants uncertainty.
• 18:51
  SPEAKER_00: So we we know how fast 238 uranium and 235 uranium decay, but there's some uncertainty on how fast what that number is, and your data points often fall within that field of uncertainty.
• 19:03
  SPEAKER_00: So we're dealing with really precise data here.
• 19:06
  SPEAKER_00: I mean, really, really precise data.
• 19:08
  SPEAKER_00: Um, and the Earth Moon distance thing.
• 19:11
  SPEAKER_00: So the storyline here is that there are things called Milankovich cycles, which you can briefly summarize what those are that are climate cycles on Earth, on the modern earth, and and in the ancient earth, going back many hundreds of millions of years, I think people can trace these.
• 19:26
  SPEAKER_00: You guys thought oh, there might be Milankovich cycles in banded iron formations, which are layered sediments going really far back in time, but we don't know if they're there, and we don't know what the the the cyclicity is, what the oscillation time frame is like is it 100,000 years, is it 200,000 years, is it 500,000 years?
• 19:46
  SPEAKER_00: And so you had to go back, look at the the cycles and banded iron formations, and then date the individual banded iron formation layers or date the depositional rate of the banded iron formation, which you're kind of tackling two big scientific problems.
• 19:58
  SPEAKER_00: Bandon iron formations are a rock that are spectacular, they're of geologic interest, they're of of I mean people know about banded iron formations, general people who who don't know anything about geology know what banded iron formation is because it's a beautiful rock.
• 20:11
  SPEAKER_00: Is that the origin?
• 20:12
  SPEAKER_00: Like, what was the origin of this project that led to a couple very fancy publications and fancy journals?
• 20:18
  SPEAKER_00: What was the origin of this?
• 20:20
  SPEAKER_00: And what was the the workflow?
• 20:24
  SPEAKER_02: So uh for me, um so so this project that I worked on was it was a kind of really fortuitous uh um collaboration between uh myself and the group in Geneva when I was a postdoc, that's when it kind of started, and a group in Utrecht University, which is in the Netherlands.
• 20:44
  SPEAKER_02: So me and Urz Schalter, who was my supervisor for my postdoc, we wrote a proposal in Geneva, yeah, in Geneva.
• 20:53
  SPEAKER_02: So uh we wrote a proposal together where we kind of the lab in Geneva specialised.
• 21:00
  SPEAKER_02: I was a postdoc there on this high precision geochronology, and I was I've always been interested in um the Precambrian, kind of old rocks essentially, uh like understanding the history of the earth.
• 21:11
  SPEAKER_02: And there there was people in Geneva studying Milankovic cycles and climate and stuff like that in relatively young rocks.
• 21:21
  SPEAKER_02: And uh I was interested in old rocks, so I was uh kind of wondering whether we could search for Milankovic cycles in old rocks and what that could tell us essentially about the climate back in time.
• 21:34
  SPEAKER_02: Also, I mean I I'd heard about the fact that you could potentially calculate things like Earth Moon distance if you can quantify the different periodicities of Milankovic cycles.
• 21:46
  SPEAKER_02: So actually, Urz and I wrote a proposal where we proposed I think four different time periods in Earth's history, all in the Precambrian, where we thought that there were Josh the Pre Cambrian.
• 22:00
  SPEAKER_00: Is before like 560, 570 million years ago.
• 22:04
  SPEAKER_00: So we're back before multicellular life.
• 22:07
  SPEAKER_00: We we have far less of a rock record.
• 22:09
  SPEAKER_00: And the rock record in the Precambrian is there's less rocks preserved from the Precambrian, and they're usually more altered and more deformed.
• 22:16
  SPEAKER_00: So you don't necessarily have huge, thick sequences of sediment that's been completely undisturbed for the their entire history, like you do in the Fen Reserve.
• 22:25
  SPEAKER_00: Now I can go to the Appalachian basins and we can we can look at kilometers of sediment that is relatively undisturbed.
• 22:31
  SPEAKER_00: You can't really do that going back in the Precambrian.
• 22:33
  SPEAKER_00: So this is a difficult task, right?
• 22:35
  SPEAKER_00: Oh super difficult.
• 22:36
  SPEAKER_02: And also, I mean, as a as a geochronologist, I need to be precise here with what I say in the pre-Cambrian Cumbrian boundary, as you should know, Jesse, is 539 million years.
• 22:48
  SPEAKER_00: Excuse me.
• 22:49
  SPEAKER_00: Okay, yeah, we must be precise.
• 22:50
  SPEAKER_00: Okay, that that's that's precision at the 0.05% level, not the 2% level.
• 22:55
  SPEAKER_00: I'm a 2% precision kind of person, so Josh.
• 22:57
  SPEAKER_00: Oh dear.
• 22:58
  SPEAKER_00: Oh dear.
• 22:59
  SPEAKER_00: Oh dear.
• 23:01
  SPEAKER_00: 536, is that what you said?
• 23:04
  SPEAKER_00: 539.
• 23:05
  SPEAKER_00: Oh, excuse me, 539.
• 23:06
  SPEAKER_00: Okay, yes.
• 23:07
  SPEAKER_00: I stand corrected.
• 23:08
  SPEAKER_00: Okay.
• 23:09
  SPEAKER_00: Okay.
• 23:10
  SPEAKER_02: So you yeah, so exactly.
• 23:12
  SPEAKER_02: But I mean, basically what you're saying is is right.
• 23:14
  SPEAKER_02: I mean that the precambian rocks are often really mold, they're really altered, they've been through different tectonic cycles, they're deformed, often metamorphosed, often, and so it's it's quite difficult to find nicely preserved examples.
• 23:31
  SPEAKER_02: But I mean, as as you know, and I'm uh and I know if you look around the place, there are certain kind of windows, well-preserved windows of rocks in in different places.
• 23:45
  SPEAKER_02: And and so we wrote a proposal about four of them, which are kind of well preserved.
• 23:50
  SPEAKER_02: Actually, if I were to remember where they all were, I wouldn't be able to remember.
• 23:56
  SPEAKER_02: One was in Canada, one was in Brazil, definitely South Africa.
• 24:02
  SPEAKER_00: Which is one of them you eventually ended up going to, right now.
• 24:05
  SPEAKER_02: So in the end, yeah, actually we were what were the fortuitous thing?
• 24:08
  SPEAKER_02: Was the Dutch uh collaborators, they were like actually written as collaborators into this proposal, but it turned out that they actually wrote a proposal at exactly the same time.
• 24:17
  SPEAKER_01: Oh, right.
• 24:18
  SPEAKER_02: And they focused um on only South Africa and only Australia.
• 24:23
  SPEAKER_02: And they focus on banded eye informations, and so banded eye informations was was just one of the four options in our proposal.
• 24:31
  SPEAKER_02: And so then actually, uh once both of us got funded, we decided we were we were in contact after that, and we said, Oh, why don't we go to the field together?
• 24:41
  SPEAKER_02: And so we went to South Africa.
• 24:44
  SPEAKER_02: We went to um a place called I mean it's it's kind of in the um where is it in the Central Cape, which is uh in northern South Africa, essentially, northern central South Africa.
• 24:56
  SPEAKER_00: And and this is a a sequence of banded informations, I'm guessing, right?
• 25:01
  SPEAKER_00: You that you went to.
• 25:02
  SPEAKER_00: And the goals were to look well, first of all, let's let's talk about Milankovic cycles really quickly, because I think uh you know any intro geoscience student will have at least one lecture on Milankovic cycles.
• 25:15
  SPEAKER_00: And there are a couple different versions of Milankovic cycles, but they all relate to Earth's orbit or Earth's kind of wobble and axis and tilt and things like that.
• 25:24
  SPEAKER_00: So there's eccentricity, which is the basically is the Earth's orbit a circle or an oval?
• 25:30
  SPEAKER_00: And if it's an oval, how offset is it from the sun?
• 25:32
  SPEAKER_00: It kind of wobbles a little bit, and that has a about a hundred thousand year cycle today.
• 25:37
  SPEAKER_00: Obliquity has about a 41 uh thousand year cycle, and then axial precession, which is kind of the wobbling of the top, is about a 26,000 year cycle.
• 25:47
  SPEAKER_00: And so those cycles are current, well, that's what it's on Earth today, and in the recent past, I mean, I think people pretty convincingly, I'd be curious how far back we we think those cycles exist in the rock record at those levels.
• 26:02
  SPEAKER_00: But is it safe to say tens to maybe hundreds of millions of years, those kind of cycles map into the rock record?
• 26:09
  SPEAKER_00: I mean, people use this for geochronology to go back and they actually count the hundred thousand year cycles to get back, you know, many millions of years ago in the rock record.
• 26:18
  SPEAKER_00: I mean, is that that's an accurate statement?
• 26:21
  SPEAKER_02: Um yeah, I think so.
• 26:22
  SPEAKER_02: I mean, actually we can we need to again be precise here.
• 26:26
  SPEAKER_02: The the these cycles, they so let eccentricity or precession obliquity, these are the names of them, as you're saying.
• 26:33
  SPEAKER_02: I mean, we have to think about the these periodicity as like changes in amount of solar radiation that the earth is having, essentially.
• 26:44
  SPEAKER_02: So e eccentricity, like you said, is kind of how circular or oval the orbit of the earth is around the sun.
• 26:53
  SPEAKER_02: And so if it's oval, it means that at certain periods as it go as the earth goes around the sun, it's further away.
• 27:01
  SPEAKER_02: And that means that at that time when the earth is further away from the sun, because the orbit is more oval, it's actually receiving less solar radiation.
• 27:11
  SPEAKER_02: That's right.
• 27:11
  SPEAKER_02: Therefore, it's a little colder.
• 27:13
  SPEAKER_02: And so that's it.
• 27:15
  SPEAKER_00: I forget which orientation it works, but is it the southern hemisphere summer is cooler when the it's more eccentric orbit or something like that, or the northern hemisphere summer is is cooler because it's further away in that that part of the orbit around the sun or something along those lines, right?
• 27:32
  SPEAKER_00: Yeah, so so and that'll that'll oscillate.
• 27:34
  SPEAKER_00: But these these 100,000 year cycle, 41,000 year cycle, 26,000 year cycle, they work together, right?
• 27:40
  SPEAKER_00: So sometimes they they fight against each other with the amount of radiation that's hitting any point in Earth.
• 27:45
  SPEAKER_00: Um, and sometimes they they feed back positively with each other.
• 27:48
  SPEAKER_00: So we end up with yeah, well, yeah, I don't I don't want to cut you there, but that's actually an extremely important point.
• 27:56
  SPEAKER_02: Um there is uh basically actually so there's the three cycles eccentricity, obliquity, and procession.
• 28:04
  SPEAKER_02: And eccentricity and procession, those are the two uh that uh interfere with each other, essentially.
• 28:12
  SPEAKER_02: Um so they've got different periodicities, but when you see a big signature of eccentricity, you also see a big signature of procession.
• 28:22
  SPEAKER_02: And so when you see eg eccentricity is small, procession is small.
• 28:27
  SPEAKER_00: Okay.
• 28:28
  SPEAKER_02: So they those those two cycles interact with each other, whereas the obliquity cycle is more consistent and kind of on its own.
• 28:36
  SPEAKER_02: Okay, it's kind of separate.
• 28:37
  SPEAKER_02: Okay, so procession is the spin of the axis, the kind of wobble of the axis, and then uh eccentricity is the uh the the whether it's circular or oval.
• 28:48
  SPEAKER_02: There's other ones as well.
• 28:50
  SPEAKER_02: But what's kind of cool is that there's these kind of um models for how all of these cycles interact and how they have changed back in time.
• 29:02
  SPEAKER_02: So this this is kind of the start of the story, I guess, a little bit, is that these models, there's there's these very clever astrophysics people.
• 29:10
  SPEAKER_02: Um I mean, I've seen them, but I mean they're too clever for me to speak to.
• 29:16
  SPEAKER_00: Uh they're physicists, ultimately.
• 29:18
  SPEAKER_02: They're very physicists.
• 29:19
  SPEAKER_02: They're too clever for anybody to speak to.
• 29:20
  SPEAKER_02: They're made too clever for me.
• 29:24
  SPEAKER_02: Um they uh and the they they've they've made a model of kind of how these things change over time.
• 29:32
  SPEAKER_02: And and so we're speaking about like astrophysics stuff, it's about gravity, and so all kinds all of the other planets are involved in the in these Milakovich cycles.
• 29:42
  SPEAKER_00: They actually Yeah, like you Jupiter and Neptune matter, right?
• 29:45
  SPEAKER_00: These huge gravitational wells way out in space.
• 29:48
  SPEAKER_00: So so one more data point about the modern earth, then we can get into the story, is that we we know pretty well, we can watch it happen basically, is that the moon is moving away from the earth by what?
• 30:00
  SPEAKER_00: It's like three centimeters a year, three point or four, four centimeters a year, so centimeters a year.
• 30:04
  SPEAKER_00: Three centimeters a year, okay.
• 30:05
  SPEAKER_00: It's moving away from Earth.
• 30:07
  SPEAKER_00: And we know that that can't have been happening for all of geologic time.
• 30:12
  SPEAKER_00: That's not a constant rate, because if we just calculate that backwards and say, oh, the moon has let's say it's been moving towards Earth three centimeters a year back in time, it would have been at the earth like 1.5 billion years ago, is that right, or something in that order?
• 30:27
  SPEAKER_02: Exactly.
• 30:28
  SPEAKER_00: I mean, because which we know is not true.
• 30:30
  SPEAKER_00: We know the moon is at least 4.3 billion years old.
• 30:33
  SPEAKER_00: Um, and so it the clearly the rate that it's moving away from Earth right now is not been has not been constant throughout all of geological time.
• 30:41
  SPEAKER_00: And so the question begs itself what's going on with the moon?
• 30:45
  SPEAKER_00: What how's it been how's it been working in in in in and working with Earth's orbit here?
• 30:50
  SPEAKER_00: So sorry to interrupt you there, Josh.
• 30:51
  SPEAKER_02: But um, so I mean uh all I was gonna say is that there's this really nice model that includes the recess recession of the moon, actually, and it it includes changes in all of the other orbits of the different planets and even even comets and stuff coming through our our solar system.
• 31:10
  SPEAKER_02: Um there's there's there's a astrophysics model for how that all of that stuff relates to the incoming solar radiation on our planet.
• 31:21
  SPEAKER_01: That's the same thing.
• 31:23
  SPEAKER_00: In the incoming solar radiation, solar radiation is climate ultimately, which climate equals sediments.
• 31:28
  SPEAKER_00: Inside climate equals weathering, climate equals rain, climate equals sediments.
• 31:33
  SPEAKER_00: So we can look at glaciation and no glaciers.
• 31:35
  SPEAKER_00: Glaciation, right.
• 31:36
  SPEAKER_00: So so we can look at these set a whole bunch of cycles in the Earth's system.
• 31:40
  SPEAKER_00: We can look at rocks preserved back in time, we can look at you know uh mud logging from interglacial lakes and this kind of stuff, and see some of these records, right?
• 31:47
  SPEAKER_00: So we could see this periodicity in these records because it's it's ultimately related to climate independent of tectonics, or or climate on top of tectonics, like an additional forcing on top of the sort of climate cycle on Earth.
• 32:00
  SPEAKER_00: So, all right, sorry, your model, this astrophysical model.
• 32:03
  SPEAKER_02: The cool thing is this model, this model, we've got this really nice model, and it goes back from today, essentially, back 60 million years, uh, maybe 55, maybe 50, 55 million years.
• 32:16
  SPEAKER_02: And so actually, if you look at the model, there's basically the model is a kind of curve, it's like a wiggly wiggly curve with all of these different cycles all included in it, and you can compare that curve to the rock record, and the match is like it's it's really astounding.
• 32:34
  SPEAKER_02: I mean, it's amazing.
• 32:36
  SPEAKER_02: If the the rock record back 50 million years, you said, or 60 somewhere there?
• 32:40
  SPEAKER_02: About 50 50 to 60 million years.
• 32:43
  SPEAKER_02: Okay.
• 32:43
  SPEAKER_02: Um it matches really well.
• 32:45
  SPEAKER_02: But after that, it doesn't match at all.
• 32:49
  SPEAKER_02: It doesn't match.
• 32:52
  SPEAKER_02: Okay, it goes haywire.
• 32:53
  SPEAKER_02: This yeah, yeah.
• 32:54
  SPEAKER_02: I mean, if you if you look at some of these papers, uh, like I say, they're too complicated.
• 32:58
  SPEAKER_02: It goes crazy.
• 32:59
  SPEAKER_02: It's not it there's this kind of chaos in the system.
• 33:02
  SPEAKER_02: They don't really know why.
• 33:04
  SPEAKER_00: Okay.
• 33:04
  SPEAKER_00: I mean we we okay, we're we're being a bit facetious here about the physicists, but uh it's pretty impressive to get 50 million years on earth really, really accurately right.
• 33:13
  SPEAKER_00: Um but then if it goes haywire, obviously we have a problem.
• 33:16
  SPEAKER_00: Um and we're not understanding something, right?
• 33:19
  SPEAKER_02: There's there's something in that that's not clear.
• 33:21
  SPEAKER_02: But we can kind of assume that the earth was still there before 50 million years ago.
• 33:28
  SPEAKER_02: We can kind of assume that the sun was also there.
• 33:30
  SPEAKER_02: I mean, uh, these are general assumptions that I mean most people would be okay with, I would say.
• 33:37
  SPEAKER_00: Okay, good.
• 33:37
  SPEAKER_00: Maybe not everybody, but I think I'm following.
• 33:39
  SPEAKER_00: I'm tracking so far.
• 33:40
  SPEAKER_02: Yeah, all right, all right, I buy it.
• 33:42
  SPEAKER_02: Um so I mean we can we can blame the models.
• 33:44
  SPEAKER_02: We can say that okay, maybe there's a problem here with the models, but we can maybe we can actually look at the rock record to tell us something.
• 33:52
  SPEAKER_02: Then the then you can kind of use the rock record to tell you something about like the the the physical state of the solar system.
• 34:01
  SPEAKER_02: And there's a cool link, I mean, with precession, which is another thing that's that it's that cycle that's the wobble of the Earth's axis that's kind of linked to the eccentricity, which is the orbit.
• 34:15
  SPEAKER_00: So this is the wobble, like uh Earth, the the the the like uh Earth is a spinning one, spinning top, right?
• 34:21
  SPEAKER_00: And the in the precession is how much it's wobbling, like it wobbles a little bit, then a lot, then a little bit, and then a lot.
• 34:26
  SPEAKER_00: Okay, so the inception thing, yeah, where the top is wobbling and it's kind of wobbling, and then it wobbles a little bit more and then a little bit less, and they leave us hanging, don't really know you know whether the top fell or not, right?
• 34:35
  SPEAKER_00: So it's that kind of that's the that's the thing that we're talking about.
• 34:38
  SPEAKER_00: That's precession here, is that wobbling wobbles more or wobbles less.
• 34:42
  SPEAKER_00: Okay, sorry.
• 34:42
  SPEAKER_00: So there's something interesting about precession you were saying.
• 34:46
  SPEAKER_02: Well, there's actually um a relatively simple calculation.
• 34:50
  SPEAKER_02: If you can work out the periodicity of this change in procession, you can almost directly with a simple calculation determine the distance between the Earth and the Moon.
• 35:02
  SPEAKER_00: Oh, interesting.
• 35:03
  SPEAKER_02: Okay.
• 35:03
  SPEAKER_02: So that that's what we targeted essentially with our study.
• 35:08
  SPEAKER_02: Is that if yeah, we wanted to see if in kind of relatively well preserved sediments in very, very old in Earth's history, we can find a signature of procession.
• 35:20
  SPEAKER_02: Okay.
• 35:21
  SPEAKER_02: Interesting.
• 35:21
  SPEAKER_02: Because we knew that there's a relatively simple calculation you can do to just turn procession.
• 35:28
  SPEAKER_02: And so the cool thing is also if you get Earth-Moon distance, you also get another thing which is kind of cool, which is the length of the day.
• 35:36
  SPEAKER_00: Yes, and that's right.
• 35:38
  SPEAKER_00: I I remember reading this in your paper, and uh it's it's very cool.
• 35:42
  SPEAKER_00: So let's let's leave that hanging for a minute.
• 35:44
  SPEAKER_00: Uh, because I want to I want to come back come back to that.
• 35:47
  SPEAKER_00: Let's end with the length of the day.
• 35:48
  SPEAKER_00: Um, what did you measure?
• 35:50
  SPEAKER_00: I mean, because you so you're going to these big banded iron formation patches, which are, as the name implies, banded iron silica interbeds, is the typical one.
• 35:58
  SPEAKER_00: You got an iron-rich layer, a silica-rich layer.
• 36:00
  SPEAKER_00: And what are you mapping to capture the cyclicity?
• 36:03
  SPEAKER_00: And then the second question is how do you date that and how do you tell what the length of the cycles are?
• 36:07
  SPEAKER_02: Yeah, I mean, it's a great question, actually.
• 36:09
  SPEAKER_02: I mean, um, so we could speak for hours about banded iron formations.
• 36:14
  SPEAKER_02: They're like really they're super I mean they're they're really fascinating.
• 36:17
  SPEAKER_02: They're they're like super useful.
• 36:19
  SPEAKER_02: They tell you so much about like the history of the earth.
• 36:22
  SPEAKER_02: I mean, uh really cool rocks, and they're incredibly controversial too in the scientific literature.
• 36:27
  SPEAKER_00: Yeah, yeah, yeah.
• 36:28
  SPEAKER_02: Yeah, yeah.
• 36:29
  SPEAKER_02: I mean, there's so many options for how they could be formed.
• 36:32
  SPEAKER_02: Um really crazy.
• 36:34
  SPEAKER_02: I mean, but they're they're also very beautiful, as you say.
• 36:38
  SPEAKER_02: Um, what we did uh in our study was we kind of stepped back from a lot of the controversy.
• 36:45
  SPEAKER_02: We didn't really go into detail about the I mean exactly how they were formed.
• 36:51
  SPEAKER_02: Okay.
• 36:52
  SPEAKER_02: We came with uh hypothesis that there is cyclicity preserved in these rocks.
• 37:01
  SPEAKER_02: Okay.
• 37:01
  SPEAKER_02: That was that was our that was our hypothesis.
• 37:03
  SPEAKER_02: That was it.
• 37:04
  SPEAKER_02: So we wanted to see if we could find it, if it's there or not.
• 37:08
  SPEAKER_02: Yeah.
• 37:08
  SPEAKER_02: And what we did is something really, really simple.
• 37:11
  SPEAKER_02: I mean, uh much more simple than uh most people would imagine, based on the kind of fancy stories we managed to get out of this stuff.
• 37:20
  SPEAKER_02: We did really simple stuff.
• 37:22
  SPEAKER_02: Um so banded iron formations, like you say, uh they're they're kind of classically thought of as like layers, thin layers, kind of at the centimetre scale of iron oxide minerals like magnetite, hematite, which is just iron and oxygen, and then chert, which is uh silica and oxygen.
• 37:41
  SPEAKER_02: So like iron-rich, silica rich, iron-rich, silica rich.
• 37:45
  SPEAKER_02: But actually, uh if you step back from the rocks a little bit, I mean when you're looking at banded iron formation in the field, if you step back away from like really centimeter scale, there's also other stuff in there.
• 37:58
  SPEAKER_02: There are kind of shaley units, which are like fine-grained siliciclastics.
• 38:03
  SPEAKER_02: There's also kind of iron-rich carbonates.
• 38:05
  SPEAKER_02: So there's it's not when you speak about iron banded iron formation, everybody only looks well, and not everybody, yeah, yeah, nobody's not.
• 38:14
  SPEAKER_02: But people really concentrate on the iron and the silica.
• 38:17
  SPEAKER_00: We look we look at the silver and purple rock part, which is the the theory.
• 38:23
  SPEAKER_00: I mean it's really really pretty.
• 38:24
  SPEAKER_00: It's rare.
• 38:25
  SPEAKER_02: Well, it's not rare, but it's really beautiful.
• 38:27
  SPEAKER_02: Whereas actually above that and below that, there is kind of a more carbonate-rich area, like uh there's a more kind of siliciclastic area.
• 38:38
  SPEAKER_02: I mean, all fine-grained rocks, but it's there's kind of less of the banded iron formation, classic iron silica, and a bit more carbonate.
• 38:48
  SPEAKER_02: And then there's some areas with a bit more siliciclastics.
• 38:51
  SPEAKER_02: And so actually, the banded iron formations, um, we we went to go and see them in the field.
• 38:57
  SPEAKER_02: The the classic banded iron formations, they make up these kind of cliffs because it's this the rock is really hard.
• 39:05
  SPEAKER_02: Um, and you know, it's difficult to I mean, you can hit it with your hammer and it just bounces off.
• 39:09
  SPEAKER_02: It's actually quite quite difficult to take a piece of it.
• 39:11
  SPEAKER_02: Um, but the other parts, the kind of the carbonate rich areas and the celestial rich, the shaley areas, they're much softer.
• 39:20
  SPEAKER_02: And so if you step back from the outcrops and you look at it from a like a I mean a few hundred metres away, what you see is kind of a cliff where you find a banded eye formation, then you see a kind of a shallowish slope, where actually you've got the kind of more carbonatey rich part.
• 39:38
  SPEAKER_02: Sure, sure.
• 39:38
  SPEAKER_02: Then you've got another cliff, maybe for another part of banded eye formation, then maybe you've got a bigger slope because maybe you've got a little bit more carbonate in this part, or maybe a little bit of maybe a little bit of shale or something, then maybe you've got a really small little part of cliff from the banded eye formation.
• 39:55
  SPEAKER_02: And so what we actually did is we kind of logged what what is the weathering profile?
• 40:02
  SPEAKER_02: I mean, so when when I say like a slopey part, it means that it it's kind of weathered there.
• 40:08
  SPEAKER_02: And and whether it's steep cliff, it's kind of what we would call that hard or injurated is the kind of fancy word for a hard thing that's difficult to erode.
• 40:17
  SPEAKER_00: Oh, of course, there's a fancy word for it.
• 40:19
  SPEAKER_00: Yeah, I didn't okay, injurated.
• 40:21
  SPEAKER_00: So this is uh this is the you know, people could imagine, I think visually the Grand Canyon or something on a small scale, where we've got cliff forming units and then and then slope forming units, and and and you know, you've got shales that are the the slope forming ones, and you've got either sandstones or limestones, typically are the cliff forming ones.
• 40:39
  SPEAKER_00: But I think anybody who's been in the western United States who's been in any of these kind of arid environments with a big canyon in it can imagine that cliff slope, cliff, slope thing.
• 40:47
  SPEAKER_00: But you're just looking at this on a much smaller scale.
• 40:49
  SPEAKER_00: Like what is the height of the cliffs?
• 40:50
  SPEAKER_00: Are they a couple meters or less than?
• 40:53
  SPEAKER_02: No, no, no.
• 40:53
  SPEAKER_02: Well, the the cliffs, yeah, maybe the cliffs are up to five up to up to maybe five meters of cliff.
• 41:01
  SPEAKER_02: Um so we're we were kind of logging over that's about 15 feet for the Americans in the audience, yeah.
• 41:07
  SPEAKER_02: Ah, oh yeah, sorry.
• 41:08
  SPEAKER_02: About yeah, maybe 80 meters.
• 41:11
  SPEAKER_02: Uh feet, I don't know.
• 41:13
  SPEAKER_02: So like maybe a hundred meters.
• 41:15
  SPEAKER_02: That kind of that kind that that's the kind of thickness of the unit logging.
• 41:20
  SPEAKER_02: Okay, all right, gotcha.
• 41:21
  SPEAKER_02: Yeah, so maybe 300 feet, something like that.
• 41:23
  SPEAKER_00: And so then um that that that uh cliff, slope, cliff, slope, the the the relative height of the cliffs and the slopes are then in your in your model, these are related to eccentricity or their orbital dynamics.
• 41:37
  SPEAKER_00: These are these are Milankovic cycles represented in the rock record.
• 41:41
  SPEAKER_00: Not yet, not yet.
• 41:42
  SPEAKER_02: Okay, not yet, not in the in the model.
• 41:44
  SPEAKER_02: And then all we did, so basically what we did is we we kind of measured the thickness of all of these cliff slopes and cliff slopes, cliff slope.
• 41:53
  SPEAKER_02: And we also then we kind of stepped back and we gave the cliffs and the slopes, we kind of compared them to each other.
• 42:03
  SPEAKER_02: So basically, the steeper the cliff, we would give that a number uh if we had a scale of one to ten, for example, we would give that a nail uh if it's super steep, super sharp, we'd give that a number one, uh for example.
• 42:17
  SPEAKER_02: And the slope, if it's like really shallow, we would maybe give that a number ten.
• 42:22
  SPEAKER_02: And the and as the slope, I mean it it's it's it's it's qualitative, right?
• 42:27
  SPEAKER_02: And we would give them numbers.
• 42:29
  SPEAKER_02: And we would do it in a little uh so it was me and um the the guy that the the the other researchers from Utrecht.
• 42:36
  SPEAKER_02: And so there was a little group of us, and we would all do it independently, and we compare our numbers.
• 42:41
  SPEAKER_02: So we we logged it, the the actual thickness of all the different units, and then we would kind of qualitatively give numbers to how steep the cliffs were and how shallow or not the kind of slopes were.
• 42:55
  SPEAKER_02: Actually, I mean it it's super e super simple.
• 42:58
  SPEAKER_02: I mean uh crazily simple actually.
• 43:00
  SPEAKER_02: So we came up with this kind of essentially, then you can kind of create a kind of wave function with that data.
• 43:08
  SPEAKER_02: And you can do some kind of statistics on it.
• 43:11
  SPEAKER_00: So you can basically say at any point in the column, you know, what is it, a cliff or a slope, and what gradient is it between super vertical sharp cliff and super flat weathered slope.
• 43:22
  SPEAKER_00: So then you can kind of say there's there's an oscillation between zero and one, and I think that's the wave you're referring to, right?
• 43:30
  SPEAKER_00: Is it somewhere between zero and one here, or somewhere between negative one and one, and any point in this period, it it you can connect the dots there and basically make a curve, uh a wiggly curve out of this vertical section, right?
• 43:42
  SPEAKER_00: So so then you're doing that and you're doing that in one place or multiple locations and matching them up?
• 43:46
  SPEAKER_02: Well, so what we did is we we we did it in one place and we we did that in multiple locations over about um for the for the first study, we did it over about three hundred kilometers.
• 44:00
  SPEAKER_02: Oh, right.
• 44:02
  SPEAKER_02: No idea what that is.
• 44:03
  SPEAKER_02: Yeah, yeah, whatever.
• 44:04
  SPEAKER_02: Doesn't matter.
• 44:04
  SPEAKER_02: It's probably 200 miles.
• 44:06
  SPEAKER_00: So the same the same units, though the same rock is the same.
• 44:09
  SPEAKER_02: Exactly the same cliff is kind of exposed over, I don't know, 200 miles.
• 44:15
  SPEAKER_02: Okay.
• 44:16
  SPEAKER_02: In South Africa.
• 44:18
  SPEAKER_02: And it's relatively well preserved.
• 44:20
  SPEAKER_02: I mean, it doesn't change too much.
• 44:22
  SPEAKER_02: And we showed that this kind of cliff slope relationship stays the same.
• 44:27
  SPEAKER_02: That actually represents all of the exposure.
• 44:30
  SPEAKER_02: There's not uh it's not like we stopped at that because we were tired or something.
• 44:34
  SPEAKER_02: Yeah, yeah, yeah.
• 44:35
  SPEAKER_02: It was we that that was it.
• 44:37
  SPEAKER_02: And because the rest of it is just not exposed.
• 44:40
  SPEAKER_02: So we did everything, and what we showed is that this pattern is consistent over the whole basin.
• 44:48
  SPEAKER_02: I mean, once you show that it's consistent over a very large area, it means that there must be some large-scale forcing behind it.
• 44:58
  SPEAKER_00: Meaning some very large-scale climate forcing.
• 45:02
  SPEAKER_00: Uh it must be a very large process.
• 45:05
  SPEAKER_00: It's not one stream coming in one area dumping a bunch of sediment randomly.
• 45:09
  SPEAKER_00: That whatever is happening is affecting the entire 300 kilometer basin, um, which is a a large, a large body of water that's that's doing this, or a large coastline that everything is impacting all at the same time.
• 45:22
  SPEAKER_00: Um, okay, so then that allows you to kind of put curves, put these lines, which um might be orbital uh or related to the city.
• 45:31
  SPEAKER_02: Well, yeah, that all that all that allowed us to do was to show that there is cyclicity.
• 45:37
  SPEAKER_02: So we proved that actually there is periodicity, so the the the cycles repeat, and they repeat on kind of like five meters and twenty meters, from my memory.
• 45:49
  SPEAKER_00: And there's a big this this over a big range, the five meters, twenty meters over a big range.
• 45:53
  SPEAKER_00: Yeah, but over a massive range, yeah.
• 45:56
  SPEAKER_00: This brings up uh time, then probably.
• 45:58
  SPEAKER_02: And if we get this is where exactly this is this is so I mean at the moment we've just got depth, we've we've we've got meters or or feet or whatever.
• 46:07
  SPEAKER_02: Of sediment.
• 46:07
  SPEAKER_00: Like we're talking about a package of sediment thing.
• 46:10
  SPEAKER_02: Okay, all right, perfect.
• 46:11
  SPEAKER_02: And we we show that there is cyclicity.
• 46:14
  SPEAKER_02: That's the first that's I mean, we show that these five meters they actually repeat constantly throughout the sediments and laterally over huge distance of the the max most distance we can measure in this whole thing.
• 46:29
  SPEAKER_02: So it's the same.
• 46:30
  SPEAKER_02: And so we think, okay, there's a there's a big, there's something big behind that.
• 46:34
  SPEAKER_02: And yeah, like you say, what we need to do now is convert meters to time, and the only way to do that.
• 46:41
  SPEAKER_00: Which is for the for the listener, we're this is now depositional rate, because we're dealing with sediments, we have thickness, we need time, and so we're saying, how fast did this thing get laid down?
• 46:51
  SPEAKER_00: And if my understanding, Josh, correct me where I'm wrong here, but is that the BIF community broadly was of one and or two camps.
• 47:01
  SPEAKER_00: Like people thought that these were deposited either really, really slow or really, really fast, and and you know, a huge range in between them.
• 47:07
  SPEAKER_00: Like, we don't really we didn't know or we don't know, we did not know before this work how fast banded iron formations were actually laid down the sediments themselves.
• 47:15
  SPEAKER_00: Is that accurate?
• 47:16
  SPEAKER_00: That's completely accurate.
• 47:17
  SPEAKER_02: I mean, the the I think probably one of the most cited studies about the origin of banded iron formation, the the most one of the maybe not the most cited, but maybe the most known is one of the earliest studies by a guy called Cloud.
• 47:33
  SPEAKER_02: Um he was a prophet at um Harvard.
• 47:38
  SPEAKER_02: Um and so he said in his original work that banded eye formations are probably related to I mean the the production of oxygen uh in the oceans uh by bacteria uh cyanobacteria.
• 47:56
  SPEAKER_02: These are these are photosynthesizing cells, essentially, like the photosynthesize light and they produce oxygen.
• 48:04
  SPEAKER_02: And so this oxygen then goes into the ocean.
• 48:08
  SPEAKER_02: The ocean at that time before there was a lot of this uh photosynthesizing material, they were anoxic.
• 48:15
  SPEAKER_02: There was no no free oxygen.
• 48:16
  SPEAKER_02: So if you have anoxic without free oxygen oceans, those oceans can actually dissolve huge amounts of reduced iron.
• 48:27
  SPEAKER_02: So iron can be in two different reduced iron, two plus iron, not three plus iron.
• 48:31
  SPEAKER_02: Two plus iron, two plus three plus is oxidized iron, two plus is reduced, and so two plus reduced iron can dissolve uh huge amounts in water that does not have free oxygen in it.
• 48:45
  SPEAKER_02: So the cloud hypothesis was that if you start to produce oxygen by cyanobacteria, this oxygen uh then can be used up by the iron to change the iron from two plus to three plus.
• 49:03
  SPEAKER_02: Okay, because the idea originally was that the back the cyanobacteria that produces the oxygen, probably the oxygen was toxic to them.
• 49:13
  SPEAKER_02: So actually it was quite lucky that there was a whole bunch of iron around to use up that oxygen.
• 49:19
  SPEAKER_02: Yeah, so it was a waste product from the cells, it goes straight into iron oxidation.
• 49:26
  SPEAKER_02: So iron changed from 2 plus to 3 plus.
• 49:29
  SPEAKER_02: When iron is in the 3 plus state in the ocean, it becomes insoluble.
• 49:33
  SPEAKER_02: Okay, and precipitates out.
• 49:35
  SPEAKER_00: So it means it precipitates as a very as a as like an iron oxide mineral.
• 49:39
  SPEAKER_00: Okay, perfect.
• 49:40
  SPEAKER_00: So in this model, we've got cyanobacteria in the ocean, we've got an anoxic ocean, which is great because cyanobacteria don't want oxygen around, but they produce oxygen.
• 49:49
  SPEAKER_00: Um, and the uh the ocean is loaded with iron two plus, and they these cyanobacteria produce oxygen, that oxygen gets used up by oxidizing the iron, going from two plus to three plus, in which case the iron precipitates out, form bonds of the oxygen, and uh and forms some mineral substrate on the sea floor, which ultimately becomes the banded iron, the iron in the banded iron formation in this case.
• 50:12
  SPEAKER_00: Exactly.
• 50:13
  SPEAKER_02: So that's the original model for the origin of banded iron formation.
• 50:17
  SPEAKER_02: And so based on that model, I mean there's a period in Earth's history where we think that the oxygen rose like significantly in Earth's history, uh like in the atmosphere, there's anoxic atmosphere, and then there was kind of a more oxygenated atmosphere, which kind of suggests that there was a lot of cyanobacteria around, producing a lot of oxygen.
• 50:38
  SPEAKER_02: So they would oxidize the oceans first and then the atmosphere.
• 50:42
  SPEAKER_02: But if you have a lot of cyanobacteria oxidizing the iron, you essentially should precipitate out, you should crystallize the iron essentially, very quickly from the oceans.
• 50:57
  SPEAKER_02: This is where this idea that basically the banded iron formation should have been formed, you should be able to do uh like a hundred meters per million years.
• 51:08
  SPEAKER_00: Oh wow, that quick.
• 51:09
  SPEAKER_00: A hundred meters per million years.
• 51:10
  SPEAKER_00: That's that's the model.
• 51:12
  SPEAKER_02: I mean, it that it's that that's that was the original idea from from the original model.
• 51:17
  SPEAKER_02: And that's been kind of carried through.
• 51:19
  SPEAKER_02: Even to today, people are still suggesting that.
• 51:21
  SPEAKER_02: Wow, okay, so that's extremely fast.
• 51:24
  SPEAKER_02: I mean it's crazy fast.
• 51:26
  SPEAKER_02: Crazy fast, right?
• 51:27
  SPEAKER_02: Because they think that basically the if you have a lot of cyanobacteria, you're just just dropping iron out of the ocean like crazy.
• 51:35
  SPEAKER_02: I mean, that the means the ocean must have been really turbid, I sp I imagine, just like full of iron oxide just falling out of it.
• 51:43
  SPEAKER_00: I mean, that's insane.
• 51:45
  SPEAKER_00: I I'm uh because I I'm I'm having trouble calibrating here, because aren't normal like background sediments on the order of a few meters per million years, like your average shale or system or something?
• 51:58
  SPEAKER_00: I I don't actually know.
• 51:59
  SPEAKER_02: If we're talking about ocean sediments, I mean it I mean it we can even yeah, meter per million years is a reasonable kind of meter for deep ocean stuff, which is what this is, this is what we're talking about here.
• 52:14
  SPEAKER_02: Um yeah, we're yeah, we're this kind is probably shelf.
• 52:17
  SPEAKER_02: I mean, maybe not super deep, but a shelf.
• 52:20
  SPEAKER_02: I mean uh but still that kind of rate would not be crazy.
• 52:24
  SPEAKER_02: I mean, 10 meters per million years is also not crazy.
• 52:27
  SPEAKER_02: But they're they they were suggesting 100, which is I mean at least an order to two orders of magnitude more.
• 52:33
  SPEAKER_02: Extremely fast, yeah.
• 52:34
  SPEAKER_02: Okay, all right.
• 52:35
  SPEAKER_02: Which is like really fast.
• 52:37
  SPEAKER_02: Okay.
• 52:37
  SPEAKER_02: And so And this is I mean it this is the whole ocean.
• 52:40
  SPEAKER_02: It's not this is we're not speaking about a lake.
• 52:42
  SPEAKER_02: Okay.
• 52:42
  SPEAKER_02: We're speaking about the whole earth, essentially.
• 52:47
  SPEAKER_00: It's just a m just the the scale of these processes is just an uh unbelievable to think about.
• 52:53
  SPEAKER_00: So all right, so you've got this this this banded air formation sequence that you've mapped, you've looked at the thicknesses, the cliffs, and the shelves, and you've you've qualitatively estimated those.
• 53:02
  SPEAKER_00: You've got a now a pattern, a sort of a uh a wave function through the the log of this thing that says, okay, is it a cliff on one side, is it a shelf on the other side, and it's somewhere in but in between there.
• 53:13
  SPEAKER_00: Then how do you get these numbers?
• 53:17
  SPEAKER_02: Yeah, I mean um we were really lucky.
• 53:20
  SPEAKER_02: I mean, there is there is actually basically small tough horizons, I mean uh which is like a volcanic ash layers inside these banded iron formations.
• 53:32
  SPEAKER_02: They're kind of hidden inside shales.
• 53:35
  SPEAKER_02: Or I mean, because these rocks they're deposited in the ocean, and there's I mean it's all kind of weird rock types that you don't have nowadays.
• 53:44
  SPEAKER_02: And so there's shales deposited inside the banded iron formations, and some of these shales, they contain zircons.
• 53:52
  SPEAKER_00: Okay, right.
• 53:53
  SPEAKER_00: Um this is really fortuitous.
• 53:54
  SPEAKER_00: And actually, correct me, Josh, but I think isn't this a isn't this fairly common that there are I mean, we have these in central Pennsylvania.
• 54:01
  SPEAKER_00: We have uh the the intra-level class that I I I used to teach takes a field trip and we look at bentonite layers, which are bentonites are just volcanic ash that's been weathered, and they're maybe millimeters to centimeters thick in a package of um well, they're in carbonates and shales, but they're they're layered in there, and you can kind of see these things, and they're they're bentonites, they're they're a volcanic ash layer, and the ash will have zircons in it, and the zircons date the the timing of the eruption.
• 54:28
  SPEAKER_00: Is that the same thing you're finding here in this weird disaggregated shale, or is it different than that?
• 54:33
  SPEAKER_02: Well, essentially it's the same in that apart from the fact that the bentonite, I mean, in Pennsylvania, or I mean a lot of young younger rocks.
• 54:43
  SPEAKER_02: Yeah, you have the same bentonite up in Keba.
• 54:45
  SPEAKER_02: Yeah.
• 54:46
  SPEAKER_02: Yeah, yeah, we we do.
• 54:47
  SPEAKER_02: But you can kind of see a layer that's kind of clay, maybe, or maybe it's got a weird colour or something like that.
• 54:53
  SPEAKER_02: In the banded iron formations, it's kind of like a black shale.
• 54:57
  SPEAKER_02: So it doesn't look like a normal bentonite at all.
• 55:00
  SPEAKER_02: Not at all.
• 55:01
  SPEAKER_00: So how do you identify it in the field?
• 55:03
  SPEAKER_00: Or how did you get zero?
• 55:06
  SPEAKER_02: Well, what we did what we did, we were lucky, is that the Dutch people they got enough money with their funding.
• 55:14
  SPEAKER_02: I mean, the Dutch um Science Foundation funded a drill core.
• 55:19
  SPEAKER_02: Oh, okay.
• 55:20
  SPEAKER_02: So we actually drilled our own drill core through the Bedai Formation.
• 55:25
  SPEAKER_00: Wow.
• 55:26
  SPEAKER_02: Um yeah, we we did about um I think it was about 200 meters of shell core through through the BIF.
• 55:34
  SPEAKER_02: And so with that, what we did is we found the shale unit.
• 55:38
  SPEAKER_02: So we we tried to do it in the field, but the shales are recessive, essentially.
• 55:43
  SPEAKER_02: They're in these kind of shallowy, shallow sections, um, and they've been mostly weathered away and it they're covered in grass.
• 55:50
  SPEAKER_02: It's it's very difficult to get at it.
• 55:53
  SPEAKER_02: Actually, see, yeah, sample and really see it.
• 55:55
  SPEAKER_02: You can't sample it, and you can't can't you can't like target it.
• 55:59
  SPEAKER_02: And so without the drill core, we'd have been lost, really, really completely lost.
• 56:04
  SPEAKER_02: We were really lucky that the the Dutch group they um they got a drill core funded, and so we drilled through it through this banded eye information, and we we like chose the location, we spoke to the farmer, so we were drilling on somebody's land, obviously.
• 56:19
  SPEAKER_02: Yeah, we got some really crazy stories about this.
• 56:21
  SPEAKER_02: I mean, the the guys we were in South Africa.
• 56:25
  SPEAKER_02: The the the farmer who had the land that we used for the drilling, I mean, he had a game reserve.
• 56:31
  SPEAKER_02: So we were actually driving through, I mean, a a game park essentially to go to the drill site.
• 56:38
  SPEAKER_02: I mean, seeing all these different antelopes and I mean deer and zebra and stuff um really cool.
• 56:45
  SPEAKER_02: I mean, uh really, really cool.
• 56:47
  SPEAKER_02: And so uh from the drill core, we were able to do things like XRF measure.
• 56:53
  SPEAKER_02: Uh we were able to kind of measure different elements in the different units, and we can kind of show that there's uh higher amount of zirconium in this particular horizon, and we could sample it, sample it, then we could try and separate zircons.
• 57:07
  SPEAKER_02: And so that's what we did.
• 57:09
  SPEAKER_02: We separated zircons from quite a few different layers inside the banded iron formation, and then like visually, we could separate the visually looking at the zircons, they looked really pristine.
• 57:21
  SPEAKER_02: Like you know, when you look at zircon from ashes, um volcanic ash, they're really well formed, essentially.
• 57:28
  SPEAKER_02: They look really, really nice.
• 57:30
  SPEAKER_02: Zircon that have it's in a sedimentary rock, they're often rounded or eroded.
• 57:41
  SPEAKER_02: Okay, gotcha.
• 57:42
  SPEAKER_02: Whereas these these ones looked kind of with sharp points.
• 57:45
  SPEAKER_02: Gotcha.
• 57:46
  SPEAKER_02: That's always a good sign to show that maybe you've got more ash type zircon.
• 57:50
  SPEAKER_02: And so then we we basically dissolved those, did high precision dating on them.
• 57:55
  SPEAKER_02: I mean, actually, I mean it's much more annoying, much, much more annoying than it sounds.
• 58:00
  SPEAKER_02: I mean, I probably dated about I don't know how many, about 160.
• 58:05
  SPEAKER_02: Probably took me two years.
• 58:06
  SPEAKER_02: Yeah.
• 58:07
  SPEAKER_02: Um but in the end just a monumental amount of work.
• 58:11
  SPEAKER_02: Well, I mean the huge, huge amount of work.
• 58:14
  SPEAKER_02: But in the end, we got some really good results.
• 58:17
  SPEAKER_02: And so we could really be confident that we had ages of we had reasonable ages for all of the different ashes that we tried to date.
• 58:26
  SPEAKER_02: And with these ashes, we could kind of calculate uh deposition rate.
• 58:31
  SPEAKER_02: Okay.
• 58:32
  SPEAKER_00: So in the the line to line formation.
• 58:34
  SPEAKER_00: The visual here, I think, for people is that you've got 200 meters, let's say, drill core, where you've mapped all these sort of cycles throughout that that sequence, but and you have what, five data points, eight data points?
• 58:45
  SPEAKER_00: How many do you have?
• 58:46
  SPEAKER_00: Four data points of officers.
• 58:48
  SPEAKER_00: I think probably four.
• 58:49
  SPEAKER_00: Four, okay.
• 58:50
  SPEAKER_00: Four data points.
• 58:51
  SPEAKER_00: So four data points that have ages.
• 58:53
  SPEAKER_00: And is this the one that's like two point five billion year old, Biff?
• 58:57
  SPEAKER_00: Or is this the one that's Yeah, well, it's two point, I mean it's well, if if we we have to get back to our preceding.
• 59:04
  SPEAKER_00: God, okay, let's be precise, Jess.
• 59:06
  SPEAKER_00: Yeah, what is it exactly?
• 59:07
  SPEAKER_02: Well, I mean uh two point four eight.
• 59:12
  SPEAKER_02: Down to around about two point four six.
• 59:14
  SPEAKER_02: Okay, so that kind of time.
• 59:16
  SPEAKER_00: So you have a a 20 million year range, but you have you have basically tie points, and those those tie points have uncertainty on them.
• 59:23
  SPEAKER_00: So you can say, oh, the top point is two point uh 2.46 plus or minus something, and the bottom is 2.48 plus or minus something, and the middle is 2.473 plus or minus something.
• 59:35
  SPEAKER_00: And you can kind of fit an age model through there with uncertainty, it's kind of the key point, right?
• 59:41
  SPEAKER_00: Like you can get a depositional rate plus uncertainty at every point in that history in that full 200 meters with four tie points between it.
• 59:48
  SPEAKER_00: So you're kind of interpolating between data points, and there's this big cool Bayesian statistical model that people use for these types of things now.
• 59:56
  SPEAKER_00: Um, but what's the depositional rate?
• 59:59
  SPEAKER_00: You were talking about the the original model, the cloud model, um, the famous Preston cloud cloud model that's sort of a hundred mil a hundred meters per million years.
• 1:00:07
  SPEAKER_00: Per million years.
• 1:00:08
  SPEAKER_00: Very fast.
• 1:00:08
  SPEAKER_02: We got ten.
• 1:00:10
  SPEAKER_02: Ten, okay.
• 1:00:11
  SPEAKER_02: Okay.
• 1:00:11
  SPEAKER_02: Ten meters per million years.
• 1:00:13
  SPEAKER_02: And so I mean, ours is based on data, real data.
• 1:00:16
  SPEAKER_02: We're the hundred meters per million years is is a is a model, not actually based on on any data, to be honest.
• 1:00:23
  SPEAKER_02: And I mean other papers have tried to um speak about that.
• 1:00:27
  SPEAKER_02: Uh but they they've kind of discussed it and then made kind of little cartoon sketches.
• 1:00:32
  SPEAKER_02: And then Yeah, yeah, yeah.
• 1:00:34
  SPEAKER_00: But this is real geochronology.
• 1:00:35
  SPEAKER_00: This is real this is real zircon uranium-led.
• 1:00:37
  SPEAKER_00: So the real stuff.
• 1:00:39
  SPEAKER_00: I mean, all facetiousness aside, this is the gold standard of geochronology.
• 1:00:44
  SPEAKER_00: We cannot do better as a field than uranium, zircon uranium-led geochronology like this.
• 1:00:48
  SPEAKER_00: And so you're getting 10 meters per million years through this package rocks, so much slower.
• 1:00:54
  SPEAKER_00: Then bring us full circle to the the cycles now.
• 1:00:57
  SPEAKER_00: What is that these five-meter cycles or whatever, 20-meter cycles, whatever they were, what does it mean in for Earth-Moon distance and what does it mean for precession?
• 1:01:07
  SPEAKER_02: So the five meters is that it's not exactly five, it's a little bit less than five-meter um cyclicity.
• 1:01:13
  SPEAKER_02: That actually converts with our depositional rate to uh about four hundred thousand years.
• 1:01:22
  SPEAKER_02: And the longer cycle that converts to about uh 1.6 million years.
• 1:01:28
  SPEAKER_02: 1.6 million.
• 1:01:29
  SPEAKER_02: And so actually, 400,000 years is exactly the time period you would expect for eccentricity.
• 1:01:40
  SPEAKER_02: So on the modern Earth, I mean, the eccentricity, which is the I mean the the orbit, whether it's more elliptical or more circular, those have um principal periodicities of 400,000 and 100,000, actually.
• 1:01:54
  SPEAKER_02: So we found the 400,000 one and the 1.6 is actually another longer period eccentricity signal.
• 1:02:03
  SPEAKER_02: I mean, it's not unusual to find that in a in a long scale record.
• 1:02:07
  SPEAKER_02: So the scale that we were logging at is at the kind of maybe 20 centimeter resolution.
• 1:02:15
  SPEAKER_02: We were not doing high because we were looking at the slope or how steep the cliffs were, we were not able to identify cyclicity at higher frequency.
• 1:02:25
  SPEAKER_00: Higher frequency, sure.
• 1:02:26
  SPEAKER_00: Gotcha.
• 1:02:26
  SPEAKER_02: Which you which is what you need for like the looking at a procession.
• 1:02:31
  SPEAKER_02: Modern procession is is what like 24,000 years.
• 1:02:35
  SPEAKER_02: Sure, okay.
• 1:02:36
  SPEAKER_02: Um so our logging was not like 400,000 years, which is uh an eccentricity time scale, is that's kind of the limit of the the time period we can see with that kind of logging.
• 1:02:49
  SPEAKER_02: Yeah, yeah, yeah.
• 1:02:49
  SPEAKER_02: Okay.
• 1:02:50
  SPEAKER_02: So we actually found it.
• 1:02:51
  SPEAKER_02: But I mean, what we've I mean, we were really impressed because it's it's crucial.
• 1:02:56
  SPEAKER_02: I mean, we people think that the eccentricity, which is 100,000, 400,000, and then there's a few longer time periods, that's kind of considered the Earth's metronome.
• 1:03:05
  SPEAKER_02: That's what it's kind of called.
• 1:03:07
  SPEAKER_02: People think that the eccentricity signal, this hundred thousand, four hundred thousand, that's kind of consistent over all of Earth's history.
• 1:03:15
  SPEAKER_02: And so that that's actually what we were we needed to find that.
• 1:03:19
  SPEAKER_02: So if you find that, people can be more convinced that you've really got Milankovich cycles.
• 1:03:25
  SPEAKER_00: Yeah, yeah, I see.
• 1:03:25
  SPEAKER_00: Okay, yeah, because those should be back up.
• 1:03:27
  SPEAKER_00: Those should be there.
• 1:03:28
  SPEAKER_02: Those should those should be there.
• 1:03:30
  SPEAKER_02: Okay.
• 1:03:30
  SPEAKER_02: And so we found it.
• 1:03:31
  SPEAKER_02: Yeah, yeah.
• 1:03:31
  SPEAKER_02: And so that we were really, really, I mean, we're super happy with that.
• 1:03:35
  SPEAKER_02: But I mean it that that was the first study we did, was just proving that there is Milankovic cycles there.
• 1:03:41
  SPEAKER_02: And after that, we kind of wanted to go a little bit deeper.
• 1:03:44
  SPEAKER_02: We wanted to try and find this precession thing, because that's like I mean, that was the real that was the real Which is the now we're we we have to map it the sort of centimeter scale and look at the case.
• 1:03:53
  SPEAKER_02: Yeah, now we need to really go more precise.
• 1:03:55
  SPEAKER_02: Okay, gotcha.
• 1:03:56
  SPEAKER_02: We need to we need to look at things that are cyclicity on a like a more centimeter scale, exactly.
• 1:04:01
  SPEAKER_02: Gotcha.
• 1:04:02
  SPEAKER_02: And we could not do that in South Africa.
• 1:04:04
  SPEAKER_00: Okay, because the rocks don't allow us to.
• 1:04:07
  SPEAKER_00: Yeah, I see what you're saying.
• 1:04:08
  SPEAKER_00: Okay.
• 1:04:08
  SPEAKER_00: So the first thing in South Africa is I don't I hadn't really appreciated this, is is kind of confirming Milankovic cycles because you needed to see this 450,000, 460,000 year cycle, and and you saw it with the the mapping that you did and the in the the sort of as you described, the relatively simple mapping and the geochronology, the two years of work geochronology.
• 1:04:28
  SPEAKER_00: So then you decided to go to is this where we go to Australia?
• 1:04:31
  SPEAKER_00: Is this where we go to Hammersley?
• 1:04:32
  SPEAKER_00: Yeah, exactly.
• 1:04:33
  SPEAKER_00: It's when we go to Hammersley Basin in Australia.
• 1:04:35
  SPEAKER_00: Okay, which is a famous huge iron mining district.
• 1:04:38
  SPEAKER_00: I mean, these are the this this is an astronomically big um no pun intended iron deposit there in the banded iron formation, a very, very famous location.
• 1:04:48
  SPEAKER_00: I mean here you have really big cliffs of of Banded Iron Formation exposed.
• 1:04:54
  SPEAKER_02: What you have there, which is um really important for us, I mean, is these gorges.
• 1:04:59
  SPEAKER_02: I mean, it it's a bit like the Grand Canyon, it's not quite as impressive as the Grand Canyon, but it I mean it's uh it's that kind of style.
• 1:05:06
  SPEAKER_02: There's these rivers flowing through, I mean, arid desert in in northern Western Australia, um right on the edge of the Pilbara Kraton.
• 1:05:16
  SPEAKER_02: So I mean these these are old rocks, there's sediment sitting on the side of these very, very old rocks, and there's rivers going through that, cutting really beautiful cliffs through spectacular.
• 1:05:28
  SPEAKER_02: I mean, really it's really, really spectacular.
• 1:05:32
  SPEAKER_02: Um, cliffs through these rocks.
• 1:05:34
  SPEAKER_02: And so there's actually like the Grand Canyon, there's kind of paths down the cliffs.
• 1:05:38
  SPEAKER_02: Okay, yeah, so you can kind of walk next to the rocks, and they're they've just been polished by the water, and and and really, really cool, really beautiful.
• 1:05:50
  SPEAKER_02: It's a it's a national park.
• 1:05:51
  SPEAKER_02: Uh, it's it's so nice there, and we were so lucky to just kind of we I mean, we're doing field work there, camping in a national park, being paid to.
• 1:06:00
  SPEAKER_02: just go and hang out.
• 1:06:03
  SPEAKER_00: That's spectacular.
• 1:06:04
  SPEAKER_00: So I mean really, really nice.
• 1:06:06
  SPEAKER_00: So in this place you did the more precise logging, I'm guessing here to to kind of get you know more precise logging and then the same kind of geochemical sampling the or geochronological sampling, targeting zircon bearing beds basically or yeah we did the same we did more hyper resolution logging.
• 1:06:21
  SPEAKER_02: I mean really centimeter scale we tried to like measure the concentration of different elements using a XRF like a little um like a machine that we took into the field and it kind of gives you the chemical composition of the rocks.
• 1:06:34
  SPEAKER_02: It's not super precise but we did that um to try and get a like a kind of a record through the rocks.
• 1:06:41
  SPEAKER_02: We did logging and for the geochronology sampling we were also again really lucky the Geological Survey of Western Australia they have drilled drill core well I don't know if even they've done it but they've got drill core in the geological survey that goes through all of these units.
• 1:07:03
  SPEAKER_02: Oh right so we didn't have to do it ourselves.
• 1:07:05
  SPEAKER_02: It's also in a national park and so they they were really against us sampling and they would didn't really want us to definitely not bring drill rigs and stuff like that.
• 1:07:14
  SPEAKER_02: But the so they that there was already drill core available and so with collaborators in the in the geological survey they allowed us to sample the drill cores and so we had this exactly the same stuff.
• 1:07:26
  SPEAKER_02: We found the same kind of layers as we did in South Africa with the zircon bearing things and we also dated them in the same way and we found exactly the same depositional rate.
• 1:07:37
  SPEAKER_02: Exactly the same.
• 1:07:38
  SPEAKER_02: I mean the rocks are deposited at essentially the same time periods I mean precisely at the kind of million year level back at 2.4 billion years I mean it was quite crazy.
• 1:07:51
  SPEAKER_02: So that the the depositional rate is exactly the same there's also small inflections in the depositional rate that happened at exactly the same time in the two uh the two areas Australia and South Africa so we were like we were super happy really impressed by the rocks by the results and so that the this 10 meters per million years is consistent.
• 1:08:12
  SPEAKER_02: Matches across these two packages of rocks okay matches across the two continents essentially um so it gives you extra confidence that it's kind of correct the cyclicity we found again the 4000 years but now with our with this cliff section we could find the 1000 years which is the next time period the next periodicity of eccentricity and then we could also find another signature another cyclicity that was being modulated by eccentricity and so modulation that's when uh that's this interference pattern okay yeah yeah yeah where it's either making it go bigger you know making it go making the it's it's sort of if you have a uh it's something it's oscillating up and down up and down up and down every once in a go too far up or once once in a while it won't make it all the way up because it's either being in interfering positively or negatively with something else right so so that's the modulating effect it's either it's sort of suppressing it.
• 1:09:07
  SPEAKER_02: The modulating effect yeah yeah exactly so when you see the the like the 400 or the 1000 year signature really well expressed this other signature is is also super well expressed at that same time.
• 1:09:21
  SPEAKER_02: Gotcha okay when the hundred so what I mean by that is kind of when it's well expressed it means that in the cliff we're looking at the shaley units are really obvious.
• 1:09:33
  SPEAKER_02: Okay as you were saying yeah yeah yeah and so that that means that the this hundred thousand year cycle is really well expressed then there's really obvious uh other layering at a higher frequency inside that area when the hundred thousand year cyclist cycle is less well expressed it means that kind of the difference between the the steep cliffs of the biff and the kind of more shallower slopes of the shaley stuff it's it's less distinct.
• 1:10:03
  SPEAKER_02: And at the same time the small layering is also a little bit less distinct.
• 1:10:08
  SPEAKER_02: Okay.
• 1:10:09
  SPEAKER_02: So so subtle differences matter a lot for these things yeah but this combination of of both of those two things was super important.
• 1:10:18
  SPEAKER_02: Really really important because it shows that there's this link between this the higher frequency cyclicity and the lower frequency the the the hundred thousand year.
• 1:10:28
  SPEAKER_02: And so we could use that as evidence that we have procession because we know that eccentricity and procession are linked together and on the modern earth because we the Eastern Earth have that same yeah exactly okay interesting so that that allowed us to be confident because I mean you we don't know the periodicity of procession because we don't know the Earth moon distance.
• 1:10:52
  SPEAKER_00: Right, right so yes this is so we're you're trying to again to go back you're trying to calculate we know that the Earth moon distance we're going 2.46 billion years ago this is a period where I think continents are stabilizing for the first time or just a hundred million years before that they stabilized actually for for really the first major time and you're going back there we don't know the earth moon distance we know it cannot have been moving away from Earth at you know three centimeters per year as it is today.
• 1:11:18
  SPEAKER_00: But we don't really know where it was so you use this precession you you don't know the the cyclicity of precession you don't know the whether you know on the modern earth it's 24, 26 thousand years, something like that.
• 1:11:29
  SPEAKER_00: You don't know what it is back in time.
• 1:11:30
  SPEAKER_00: It's a free parameter but you are calculating it now you're showing it in relation to a hundred thousand year cycle and what is it?
• 1:11:37
  SPEAKER_00: What is the precession that you measured and and what is then the earth moon distance that you calculate from that.
• 1:11:42
  SPEAKER_02: So I mean it it's it's a little anticlimatic aspect I guess I mean we're speaking about these fancy like uh like oh we're speaking about solar system processes and now I'm gonna say oh procession was 11,000 years.
• 1:11:55
  SPEAKER_02: Well that's different great that's half that's exciting it's half it's half it is yeah we we calculate it to be about 11 to 12000 years something in that kind of range um base I mean which is completely different to the modern yeah it's a bit basically half and so if you put that into the calculation for how you can work out earth moon distance that shows that suggests that the moon was about sixty thousand kilometers closer to the earth than it is now.
• 1:12:27
  SPEAKER_00: Okay and the Earth moon distance right now is three hundred and eighty thousand kilometers and so you're saying it's three hundred and twenty thousand kilometers roughly it was about three hundred and twenty thousand kilometers plus or minus two several thousand kilometers probably somewhere in there.
• 1:12:41
  SPEAKER_00: Yeah um but but you're saying okay it's significantly closer 6000 kilometers closer so earth was a lot closer it'd be a lot bigger in the sky and also the uh I want to let's come full circle here as we kind of wrap wrap this story up because I mean it's just amazing to me that you can do this with gyrochronology.
• 1:12:57
  SPEAKER_00: This is the the cutting edge gyrochronology that if we did not have the tools and and instruments and the techniques that you and your colleagues in your your field have developed over the years we could not do this work.
• 1:13:07
  SPEAKER_00: We have to have ultra precise geochronology in order to do this type of work that you're doing.
• 1:13:11
  SPEAKER_00: But 2.5 billion years ago Josh how long was a day well we calculated it and it was about 17 hours.
• 1:13:20
  SPEAKER_02: 17 hours 17 hours so that means the earth was spinning much much faster than it does now.
• 1:13:26
  SPEAKER_02: Yeah I mean crazy.
• 1:13:28
  SPEAKER_02: I mean you know what I've I'm just completely because for me I'm I'm a geochronologist right so I I've lost a little bit of that awe from dating things because it's my job yeah and it's what I do.
• 1:13:42
  SPEAKER_02: Yeah yeah yeah yeah that's what I do every day.
• 1:13:45
  SPEAKER_02: So I mean I it's I I find it cool.
• 1:13:48
  SPEAKER_02: But I was so amazed that we could come up we could speak about solar system processes from just making very simple measurements in the field.
• 1:14:02
  SPEAKER_02: We measured the thickness and how steep these cliffs were yeah I mean how steep is it one to ten Josh you do it and then I do it and then we compare notes.
• 1:14:12
  SPEAKER_00: Yeah yeah it's but it's it's true it's it's basic it's basic uh I mean it is really you're right it's an amazing story making geological observations basic fundamental geological field observations with a very high-end geochronology technique that's been developed over decades and generations to get to a precision level that allows us to this so the you yeah the the the fanciness of your geochronology high precision geochronology world is not lost on me yet um and so just being able to do this geochronology I mean you're getting data points that are spectacularly precise you're getting ages that are 2.4 billion years ago and it's plus or minus 600 000 years and that's like not the best data point you have that's that's moderately good that's a spectacular precision on these ages so it's not lost I mean although it is simple the power of of of that geological intuition geological simple observations um and then some pretty advanced physics to to to calculate these things I'd imagine but um it's such a cool story man it's a cool story but for me that's the that's the kind of that's what gets me excited about geology is the fact that you can you can speak about these like global or maybe even solar system scale things by having an interesting thought experiment.
• 1:15:34
  SPEAKER_02: Yeah that's it's a lot of actually you can just test models about global processes.
• 1:15:43
  SPEAKER_02: Relative I mean with uh with with with fancy tools for sure but what you need is to have a a a like an innovative idea that's that's basically it that's that's it.
• 1:15:57
  SPEAKER_00: And there's the good news about our field is it's a pretty young field um comparatively to other fields of science and there's still a lot to be explored and we have a huge amount of time we have a lot of earth process we do not understand.
• 1:16:12
  SPEAKER_00: I mean I've talked about this before I'm super excited to be a geologist and geology professor at this point in time.
• 1:16:17
  SPEAKER_00: There's just so many problems to solve that are so interesting.
• 1:16:21
  SPEAKER_00: So I I I think this is a great example of some of the really cool science that that can get done.
• 1:16:27
  SPEAKER_00: So real quick what's the reception been on this this work?
• 1:16:31
  SPEAKER_02: I mean I know I know from talking to you offline that's it's some of it's been very positive um and some maybe ho hum but but uh what do you what's in aggregate what do you feel so I would say the the main positive thing that's come out well I mean that the actually the I mean this work is getting quite well cited so I mean it means that people are at least reading it.
• 1:16:52
  SPEAKER_02: Yeah which is good.
• 1:16:53
  SPEAKER_02: That's great.
• 1:17:02
  SPEAKER_02: Or like people studying like um the evolution of the earth doing models and trying to calculate how the earth moon system has evolved over time based on modeling.
• 1:17:14
  SPEAKER_02: This is really really complicated because um the earth moon system there's this there's I mean as we know that the moon and the earth are related in the tides a little bit and so there's a link between the tidal um system on the earth and the moon.
• 1:17:32
  SPEAKER_02: That's actually what's controlling the earth moon distance and that's kind of making the moon move further away over time.
• 1:17:41
  SPEAKER_02: But to model that back in time to to look at how this tidal influence has affected the earth moon distance you actually need to know the structure of the continents because you need to know the ocean basins.
• 1:17:56
  SPEAKER_02: You need to know the structure of the ocean basin we we really have no idea like when you go back uh into the Cambrian um which is five hundred million years ago we don't fully know exactly what the ocean basins were like and then when you go back into the pre-Cambrian like two billion years ago we don't really have any idea.
• 1:18:19
  SPEAKER_02: Right or what volume were there or where they were yeah yeah where they where they were we don't we don't know.
• 1:18:24
  SPEAKER_02: And so that that actually plays a huge role in what the ocean is doing.
• 1:18:30
  SPEAKER_02: Right?
• 1:18:30
  SPEAKER_02: I mean because ocean currents are really related to where the continents are on the earth.
• 1:18:36
  SPEAKER_02: I mean if you have a big like if you have all of the continents kind of stretching like in a thin line from the North Pole to the south pole that's a massive effect on ocean currents.
• 1:18:45
  SPEAKER_02: Right, right, right.
• 1:18:46
  SPEAKER_00: Whereas then okay so I see we're going to the oceans and the oceans have a big influence on the moon and so therefore are people reverting your model or taking your data point as a calibration point for their models of of of um cycles back in time they're what they're they're plotting our data on their models.
• 1:19:04
  SPEAKER_02: They're not I mean the physics the astrophysicists wouldn't use our data as a calibration point.
• 1:19:09
  SPEAKER_02: No no no but actually but our data is in like perfect agreement with the most advanced models.
• 1:19:21
  SPEAKER_02: It's not that they are um perfect in any stretch of the imagination because we just don't know.
• 1:19:26
  SPEAKER_02: No no no we just don't know exactly what the continents are all models are wrong just how wrong are they is is the question right so maybe we're also wrong but we are matching exactly with what the best estimates are at the moment.
• 1:19:38
  SPEAKER_02: And so I mean for me that's the kind of the coolest thing.
• 1:19:42
  SPEAKER_02: I mean it it's kind of all aligning I guess that's great to that's great to hear.
• 1:19:46
  SPEAKER_00: Yeah.
• 1:19:47
  SPEAKER_00: Well Josh I mean okay we we've we've we've talked for many hours uh about science and we've talked for a long time already on this um but I think we're gonna be keep talking about geochronology and go into the weeds certainly deep deep deep into the weeds in geochronology but I don't know the answer to this question either which is our traditional closing question which is what has been your best day as a geoscientist it's a difficult one.
• 1:20:11
  SPEAKER_02: I mean uh it's difficult it's a difficult one because I mean I I've I've worked on loads of cool projects you've been all over the place including with me up to Acasta uh you were yeah yeah I mean I mean you with you and your dad yeah yeah that's right that was I can't forget Ron I mean catching massive pike in a casta I mean that's a pretty special moment I have to say on a fly rod I mean with a can.
• 1:20:40
  SPEAKER_02: That's right.
• 1:20:41
  SPEAKER_02: Anyway For me it's it's gotta be these like these views these kind of like when I I've had a few times when I've been in the field I mean I've been recently in Namibia when you're just you you're kind of hiked to the top of a a kind of a lookout or a mountain and you're sitting on these really cool rocks I mean that are telling you about the the kind of the development of complex life and then you're looking out over the desert in Namibia and there's kind of ostriches just running across the desert and you're just thinking how how am I paid to do this?
• 1:21:20
  SPEAKER_02: Yeah yeah you know you think how lucky am I yeah but how amazing is is just the earth and being able to kind of study the earth and go to these really cool places.
• 1:21:29
  SPEAKER_02: I've had this quite a few times I mean in Acasta it's just spectacular and just sitting there and looking out over the landscape or just chatting in the evening to you and your dad I really loved it.
• 1:21:43
  SPEAKER_00: And I mean Namibia South Africa I mean all sorts of you have been to some of the most classic geological locations in the world to do to do geology not just for fun but to do the actual work which I think I agree it adds another layer when you're when you're there working quote unquote working and it doesn't feel like work it's spectacular you know you're you're you're standing there you're like I know about this area you you've it's not just you're not just rocking up to some national park that you don't know much about and just looking at the landscape and saying oh it's a pretty view you actually have done the re you've done the reading about the place you understand the rocks you know the questions you know what you're there for and what you're there after and and you're after something you're passionate and interested about it adds like a another bunch of lenses to the the view of the landscape and it just makes the landscape kind of pop in your mind a little bit of of the importance of it and the history of it.
• 1:22:35
  SPEAKER_00: So I mean it's why geologists tend to do to I think tend to look up the and spend time reading about the places they're gonna go and the rocks they're gonna see before they go places because it adds that layer of appreciation to it.
• 1:22:48
  SPEAKER_00: Except it's it's this on a on a monumental scale so well that's a spend way too much time on uh Google Earth yeah looking at satellite views of the beautiful locations we're gonna go see.
• 1:22:58
  SPEAKER_00: Absolutely absolutely well it's a bit of a cop out Josh you didn't really actually give the answer a single day but we'll we'll take it because it's a pretty good one.
• 1:23:06
  SPEAKER_00: I mean it's a pretty good theme.
• 1:23:08
  SPEAKER_00: So maybe next time we can you can think about a little more and have have have a day that there must be a day in the lab right when you get a data point you're like ooh that's exciting that's an exciting data point as well when things are working.
• 1:23:22
  SPEAKER_02: I would say more when I came to Geneva not to came to when I came to Montreal I mean it's more like I had to do it all on my own.
• 1:23:32
  SPEAKER_02: You know I had to set up a lab and when I started measuring I mean it it's not very exciting when I start to measure standards and I got the right age I mean I was just so happy you know yeah and I I measured blanks yeah and they were really good yeah yeah that's or even just the first time I got the beam on the mass recovery line oh look at this this is great it just feels so good actually things are working I mean it's it's it's not it's not necessarily just I measured this great point just the fact that I got it to work you know and I things are working as I hoped and uh I mean all of the um previous work has actually you know come to fruition a little bit with with some really cool stuff we've done but just just making it work I was really impressed yeah by you know when things work it's amazing oh I feel yeah I feel you on that one that's definitely that's a good one too all right well uh Dr.
• 1:24:42
  SPEAKER_00: Josh Davies Professor Josh Davies Joshua HFL Davies if you're looking him up on Google Scholar that's it exactly um and um uh my good friend uh josh davies and colleague and and co-author we will have many more discussions like this in the in the coming year years here um focused on geochronology and all things deep topics and deep time but um the earth 2.4 billion years ago uh the day was 17 hours long so that's a pretty cool visual that's a pretty cool visual based on the work you've done there so awesome hey man thanks for the story uh look forward to to talking next time