PlanetGeo: The Geology Podcast
PlanetGeo: The Geology Podcast
Magnetic Sand and Other Listener Questions
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Join Chris and Jesse as they dive deep into your rock-solid questions! From magnetic sands on Lake Michigan's dunes to the ancient mysteries of plate tectonics, nowhere on Earth (or beyond) is safe from their geological curiosity. Ever wondered who names minerals or how to remember those complicated mineral formula? Tune in to this special listener Q&A episode to unearth some epic answers! Plus, find out what really rocks Dr. Reimink's boat. Don't miss it!
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And where did they move to over that 500 million years? And if they're moving in different directions at different parts of the planet, then it could be a mobile-lit planet. Welcome to Planet Geo, the podcast where we talk about our amazing planet, how it worked, and why it matters to you. Why do I work with you? Why do I do this with you? Gosh, I have I'm forced to spend time with you. Chris, we had a um I was very happy with thank first of all, thank you to all the listeners who sent in listener questions. This was we had an overwhelming response, I think, with uh a number of questions, many, many, many questions, far more than we'll be able to get to today. Um, and many of the questions are really good and uh require us to to really answer the questions fully. We thought, oh, we'd got to do a whole episode on this. So there's a bunch of questions. If you're sitting there listening to this, there's a bunch we're not gonna get to today, but you know, stay tuned. We're hoping we're we're gonna be building a couple episodes based on some of these questions that are a little bit deeper and require more thought and nuance to them. But we're gonna go through here and hit about five questions today, Chris. Were there any themes you took away from the listener questions that we got?
SPEAKER_00No, I didn't I didn't come up with any themes, they were all over the map. Um, and uh what I like about it too, Jesse, is it came from like really, really young people that have listened to our podcast to the opposite end of the extreme where they're they're old, like me, you know? And and uh so that I like that. There was no, I didn't did you see a theme?
SPEAKER_01No, no theme whatsoever. I mean a complete okay what it showed for me was there's a uh a huge range of diversity of interests amongst the listeners, right? They're not all just thinking about igneous and metamorphic rocks like you and I are a bunch of times. Um so so I'll lead off with the first one here, Chris, and ask you the question. This comes from Adley. Uh, why is some sand magnetic?
SPEAKER_00So you're giving me a chance to talk about sand again. You know how I love sand.
SPEAKER_01I know I just love sand.
SPEAKER_00Yeah, we did an episode dedicated to actually we've we've talked a lot about sand on this podcast in the five years we've been doing this, but the I had to do some convincing on you with with the like the necessity of doing an episode dedicated to sand.
SPEAKER_01Yeah, you can't it's one of my favorite episodes. It's one of my favorite episodes now.
SPEAKER_00Yeah, um, so uh I I'll give my take to this and then just jump in, Jesse. But you know, along the shores of of Lake Michigan here, we have spectacular broad beaches, we've got dunes and so on, and we also have these really dark streaks where the where the water kind of breaks back and forth and it's rolling up onto the shore and then back into the lake and so on. You get these these bands of really black sand, and it's highly magnetic. And so if you take a if you drag like a neodymium magnet through that stuff, you it'll come up just chalked full of this magnetic material, and it's it's all the mineral magnetite. And so that that's the that's the short answer to the to the question why is some sand magnetic? It has the mineral magnetite in it. Um, and it you know, so it's a pretty easy one, Christian.
SPEAKER_01And so I yeah, that's it's mag where's the magnetite coming from? Is that where you're going?
SPEAKER_00Yeah, that's where I was going. Then you got to look at well, you know, where's the magnetite coming from? Well, you know, magnetite is is a mineral that is commonly found uh in igneous rocks. And and so you look at the derivative of where where did the sand come from? The parent rock, the material for this gets broken down into gradually into sand and then carried by rivers to the lake, which is you know my reference where I'm talking about it right now. Then you come to this well, our episode, only the strong survive, right? And so along Lake Michigan, you have it our sand is really high quality sand, it's mostly quartz. It doesn't have a lot of other stuff in it because quartz is the strong. Everything else kind of broke down and weathered away before it gets to that point.
SPEAKER_01That's right, Chris and let me just kind of paint a picture here because we're we're focusing on play painting the visual of like Lake Michigan shorelines or on the east coast, United States, very similar kind of dynamic. The east coast of the United States has a bunch of these sandy beaches and these these sort of um long barrier islands that are made of sand. Um, that sand is ultimately glacially derived, so it got scraped off of rocks to the north that are are have brought all that sediment, that glacial till down uh to this Michigan and lower eastern east coast of North America. Some of it will be derived from, in my part of the world, old sediment that's been weathered from the former Appalachian Mountains and things like that. But much of the sand around here is actually it's been reworked a lot. So you look at the rivers, I look at think of the Grand River in Michigan or think of the Susquehanna River here in Pennsylvania. It's carrying some sediment. Uh, there's for sure it's carrying some sediment, but it's not really carrying a ton of sediment these days. Like it's not high mountains that are eroding a bunch of sand off. So a lot of this sand is reworked glacial till sand. So it's just been kind of moved back and forth across the landscape, up and down by wave and ocean activity for a long time. So hence this reworking, this strong survive thing. It's not just transport in the rivers or in the glacial till, it's actually moving up and down the beach by longshore current and getting hit by waves all the time. That's a chemical and physical weathering process as well. So not only does it have to survive the river transport, it has to survive that that physical and chemical uh attack that happens on the beaches as well and in the near shore environment. So what we're left with is quartz, we get some feldspar for sure, magnetite. My uh pet mineral zircon is in there too. And so I like magnetite layers.
SPEAKER_00There's some garnets in there.
SPEAKER_01There's garnets will be in there. There's a bunch of these uh more unless common minerals that are really resistant to chemical and physical weathering. Those will all be common in these layers. And so these types of layers are really valuable to people like me who are interested in, let's say, understanding where this sediment has come from. We want to look at the zircon cargo in there. And so we'll go to these really what end up being dark layers that have magnetite, which is a dark mineral, core um garnet, which is a dark mineral, zircon, which is a dark mineral. Those dark layers will be the magnetic ones, and they have a high concentration of all of those magnetic and heavy, really dense minerals. Because those minerals I just listed are really dense compared to quartz. And so they get concentrated just by wave energy into these dark layers.
SPEAKER_00And when you look at this stuff under the microscope, like I have my my geoscience students do analyzing sand samples, the magnetite and uh coupled with the quartz is very different. The quartz tends to be much, much bigger, you know, roughly twice the size of a magnetite grain. The quartz is angular, the magnetite is half the size or even smaller, and shiny. It looks it looks metallic under the microscope, and it's very, very well rounded. I mean, they're almost like spherical beads. Um, and but that's because it's not quite as hard as quartzes. Magnetite has a you know hardness around six on the most scale of hardness, six out of ten. The thing is, is uh it's not like magnetite is at all that strong in the context of only the strong survives. It's just like you said, the source material, this is glacially derived. So in in my instance, it came out of Canada for the most part, and was just kind of sprinkled over uh the Michigan landscape. It's like this glacial kitty litter that just kind of, you know, we have 200 to 500 feet of this stuff that was just kind of sprinkled out, and then rivers rework it, and then like you said, it gets reworked along the shoreline. But this magnetite, it was abundant enough to to make that journey and survive that journey. But it's on its way, Jesse, to becoming different minerals. It's on its way to becoming, you know, girtite or or uh hematite, these these other iron oxide minerals. So it's it's not it's not nearly as stable and strong as quartz or or garnet like almondine, things like that. But it's definitely there.
SPEAKER_01That's right. And and it's so in the in the in Michigan and the Michigan beaches, you're gonna have this is stuff coming from the Canadian Shield, weathered off, carried by glaciers down, then deposited there, and then that stuff was transported by rivers out to the beaches, and then over time the wave energy has reworked this stuff, meaning it has moved all the quartz and and felt spar and and all the other minerals in these sands around, and during really intense wave energy, you can get the heavy stuff gets separated from the light stuff just a little bit. It's not a lot of separation, but just a little bit, just enough to make these dark layers in the in the sand that you can actually dig in. And we did this exercise when we were down in Florida in the panhandle. Um, I was looking for some detrital zircons in the in the sand just to do some basic tests with. And so, yeah, we just dug down, found a kind of an inch or two thick dark layer, and sampled that. And it's every it's in a lot of these sand-dominated beaches all along the east and south coast of of the United States, and many any any kind of sand environment will probably have dark layers in there if you just kind of dig down into the beach a little bit.
SPEAKER_00So that's and those those dark layers, Jesse. Those dark layers are called placers, you know, those because they settle out due to density. I think you might call it a placer, right? Placer, whichever, whichever one you prefer there. Yeah, exactly.
SPEAKER_01Just those are those are this is a density separation. So some of them are more dense, uh, they weigh more, have the same the same grain size weighs more, and so it'll it'll kind of settle out uh from the water faster than the lighter stuff, the lighter quartz, the lighter minerals in there. So that's why some sand is magnetic. It's a it's a cool story, and the magnetic sand is really interesting and very and can be valuable. People in certain areas uh people mine this magnetic sand because it contains all sorts of these other minerals in it that are that are interesting and important for um society. So that's right. Next question, Chris.
SPEAKER_00Well, thanks. Yeah. Uh this next question comes from actually one of my former students, Rachel King.
SPEAKER_01Oh, is that right?
SPEAKER_00Um Yeah, she's she's now at um the School of Mines in Colorado. So Oh, excellent. Okay, there we go. And her question is her question is when do you think plate tectonics started? And or do you think we will ever be able to know without direct evidence? And then she has a follow-up to that, but let's deal with that one first. Okay. This is right up your alley, Jesse.
SPEAKER_01Um, what's the short answer here, Chris?
SPEAKER_00The short answer is give the short, Jesse.
SPEAKER_01The short answer is we don't know very well. Now, there are entire conferences that are built around this question. When did plate tectonics begin on Earth? Like there will people will sit around, people like me will sit around for three or four days, and this is all they talk about and have different presentations, different arguments back or forth. My view is that the consensus that the majority of people who work on this thing, on this topic, think that plate tectonics stump started sometime between four billion years ago and 2.5 billion years ago.
SPEAKER_00That's a huge, huge span of time. Huge span of time.
SPEAKER_01Um but I will note there are people who disagree with that, who would disagree with that assessment. There are people who think it started 4.4 billion years ago. That's there's people who think it started 700 million years ago. Um, they're in the minority, I would, I think. Um I'm I'm trying to summarize. I'm not saying what I think, I'm trying to summarize what the community kind of on average thinks. Um it's a different.
SPEAKER_00Can we get into some of those problems, Jesse? Like what why is it so such a huge span of time from like 2.5 billion to 4 billion years old? Why is that that's a big discrepancy? How how come? Let's start with that.
SPEAKER_01There's two two reasons, I think. The first one is a problem of definitions. So when you say it the question is, what do you mean when you say plate tectonics? Because do you mean the earth has to look has to operate very much like it does today, with seduction occurring at a particular angle, um, with with ocean crust getting recycled, with volcanoes, volcanic arcs? Um, do you mean what do you what do you mean by plate tectonics? There's a kind of a tricky definition. And there's a very common or highly cited, highly referenced version of this where people, I don't necessarily I don't agree with this version actually, but people think we have what what people call cold plate tectonics today or cold subductions occurring today. Back in time, it might have been a hotter form, a kind of a squishier version of plate tectonics, but still plate tectonics, not as rigid. And then before that, there was this stagnant lid planet, which is very different from plate tectonics. And I only bring that up to say that there's there's different versions of plate tectonics that some people argue Earth had this kind of middle period, which was like a squishier version of plate tectonics, still plate tectonics, but not exactly like what we have today.
SPEAKER_00Okay, so I think, Jesse, it's safe to say that when uh the derivative of this question from Rachel, I think, is plate tectonics as we think about it.
SPEAKER_01Yeah, okay. So I'm gonna So let's deal with that definition. Let me let me give you what the the definition um framing that I really like comes from a colleague of mine and his group. They they kind of say, okay, we're not gonna use the word plate tectonics, we're gonna use the word mobile lid and stagnate lid. So stagnant lid is the planet has one lithospheric lid, one plate, and it does not ever break. Or if it does kind of like what Mars has. Mars, exactly. Perfect. The moon, same thing. Mobile lid would be that you get surface material somehow gets down into the earth, and the lid has to break. So it could be plate tectonics, it could be some other form of plate tectonics, it could be something different, but the lid is broken. So mobile lid or stagnant lid, two end members, and then there's kind of subcategories with all within both of those two end members. And so I like to think of it that way because to me it's just a little bit simpler, and the evidence you the sort of geological evidence you need to say this is mobile lid versus this is stagnant lid is a bit simpler than this is plate tectonics cold, plate tectonics warm, plate, whatever, you know. So that's one thing. So let's talk mobile lid then. Mobile lid tectonics. The other the the the issue number two, or the reason number two why this is a long-standing debate in the earth sciences, and I don't see a way, a clear way to answer this question, is because Earth has been in the mobile lid regime for at least, in my opinion, at least two billion years, probably more than two billion years. And so that mobile lid regime is great at reworking and overprinting prior rocks, and we just know this from the rock record. There's like a few parts per million of Earth's rock crust that is older than 3.5 billion years ago. That stuff probably existed, it's just been recycled, reworked, overprinted. We can't see it anymore. We talked about this in our Ursul, this rocks chapter uh audiobook. Like it's difficult to work with these things um because Earth is constantly overprinting itself. So the evidence we have it gets less and less the further back in time we go. So that just means there's more room for scientific debate because there's very few data points back.
SPEAKER_00Okay, so here's the question then What would be uh the uh thing that you would want to see? What would what discovery could definitively nail this down?
SPEAKER_01Here's what people tend to look for when you think of plate tectonics. What plate tectonics versus or let's take mobile lid versus stagnant lid? What do you need to see for mobile lid versus stagnant lid? You need to see two different locations, and there's people working on this this topic. You need to see rocks in two different locations that are the same age. So let's say we want to go to three billion-year-old rocks, and we look at three billion-year-old rocks in in South America and three billion-year-old rocks in Australia. And we look at those and we say, okay, from 3 billion to 2.5 billion, we're gonna look at the geomagnetic data from those and say, where were they on Earth and where did they move to over that 500 million year period? And if they're moving in different directions at different parts of the planet, then it could be a mobile lid planet. Then it means you have two different plates moving in different directions at different rates. So we're kind of trying to do plate reconstruction back in time, and this is like a geophysical problem. All the geochemistry that I do, all the petrology that a lot of people do, it's not a plate tectonic signal. It's looking at the magma system, like how did the melt, how did a magma form, which we kind of have to rely on our modern understanding of the world to to interpret that back in time. But with geophysics, the holy grail is kind of looking at how continents moved back in time, which is paleomagnetic data, really, is what that is. So that that's kind of in my view, the the kind of holy grail um is tracing ancient continents as they moved back in time. How fast did they move? Where were they moving? Were they moving all together as a big block, or were they kind of separated out? So I don't know, is that answer the qu answer your question appropriately? Or you're you're looking at me, you're giving me a look.
SPEAKER_00I I am. I have a lot. I mean, this this question could and maybe perhaps should be an episode alone.
SPEAKER_01Okay, well let's do it. Let's let's find a place to put a pin in it and and do that because I think it fits well with our continent stabilization uh theme that we have coming up here, so we could easily tag this on, yeah.
SPEAKER_00We've talked about this. Is it uh is this an important question to answer?
SPEAKER_01Yes, it is an important question to answer. Um the reason it's an important question to answer is that we are sitting on the only planet that has plate tectonics that we know of. We know that plate tectonics provides really important habitability feedback loops, so it it draws down CO2, you know, it does all these things that that helped.
SPEAKER_00I mean we wouldn't be able to stay here if we didn't have plate tectonics. Exactly. Yeah, so it's important.
SPEAKER_01When when we're looking, when we're just thinking, I mean, it's it's important from the sort of origin of our species. Where do we come from? Why are we here? That question is related to plate tectonics. It's also really important for understanding planetary for for understanding critical minerals deposits. Uh economic geology relies on plate tectonics deeply, and so understanding how that works back in time would allow us to explore old rock terrains, probably with a more nuanced view, if we understood whether it was plate tectonics or not plate tectonic, what processes were going on. Um, it's also really important for planetary science and astronomy. The number of people they're they're looking, finding all of these exoplanets, and when the new telescopes start to come online, you know, we're gonna find way more exoplanets. And understanding how planets evolve over time, we don't really know that very well because we have a snapshot of our planet right now. We have a little bit of data going back in time. So studying the early Earth is basically planetary science, and and we need to understand why did Earth and Venus evolve very differently.
SPEAKER_00Um I yeah, I asked the question, um, not from the standpoint of me being skeptical on it. This is just something that's like that.
SPEAKER_01You know why it's important, but it's good to answer.
SPEAKER_00Absolutely, for sure. It is. Well, I mean, you and I have talked about this, um, especially early on in your research. You know, you you you kind of you had to come up with a good answer yourself.
SPEAKER_01Yeah, absolutely.
SPEAKER_00Um you know, yeah. So okay. Um and I also think, Jesse, just to tag on to what you said, that the answering a question like this is gonna lead to things that I think we haven't even thought of yet. That are that are important and and maybe answers to to problems, uh, you know, finding solutions to problems that we have here that are surficial problems, and the answers are deep.
SPEAKER_01Um, answers are deep. That's exactly right. Yes, yep, yeah, absolutely. Understanding what what's happening at depth uh is gonna be really important for society in the future and and understanding, you know, hey, I'm standing on a billion-year-old rock uh layer at the surface, what's down beneath my feet? You know, how does how is the crust constructed beneath my feet? That is a plate tectonics question, really. Um, and so uh yeah, you're totally right.
SPEAKER_00It's kind of Chris. It's it's hold on a one thing, one other thought. It's it's interesting to think about that because we have plate tectonics, it makes it exceedingly difficult to find out when it began. That's right.
SPEAKER_01I mean, it's that's exactly right, exactly right. Because we have this very valuable process to us, uh it makes it hard to know what the heck happened back in time. Absolutely. Um, so Chris, moving to more modern geology here, we got a question from Emily Rath. Do we know what rocks are at the very bottom of the deep ocean basins and how can we study them? So deep ocean basins, what's that and what are the rocks?
SPEAKER_00Yeah, so I'm assuming, Jesse, is your take on this question that we're talking about what's at the surface on the deep ocean floor.
SPEAKER_01That's right. Right, we're not talking about below the yeah, okay. That's right. I mean, I think it's probably twofold, yes, what's at the surface and what's down below it, but but uh what's out what's out there when we go out to the deep ocean basin, so we're getting off the continental shelf or off the continents that are there's continents that is that is underwater right now, we're getting off that part into the deep ocean basin. You know, we're a couple kilometers thick uh water, what's at the bottom of that, and how do we know?
SPEAKER_00What's your answer to this one? Short answer basalt is what's on the deep ocean floor, a lot of most common surficial rock on our planet. So you want to give your is short answer, uh we good with that? Can we move on then? Like how do we know or what would be
SPEAKER_01I would modify it, Chris, to say there's there's a often a uh increasingly thick layer of like in the current oceans, like silica ooze on top. That's a third of a thin skin on top of the basalt. And then when you get closer to continents, you get sediments that are coming off too. So you get this this ooze, this chemical deposition going on at the at the deep ocean bottom, too. So that's the only modification I would use to your answer.
SPEAKER_00And you're one other thing too is you do get this thickening wedge of material that covers the basalt, uh this kind of veneer, but it it's thin in the middle of the ocean and it thickens towards the edge of the continents. Uh part of that is because the you have this land derived sediment and it's going to be thicker closer to the land, closer to the continent. And and so anyway, that thin skin is covering this basalt. How do we know?
SPEAKER_01Yeah. To kind of get at the heart of it. How how how do we as juice know that?
SPEAKER_00Well, here's my take on it, and then you give your take on it. Um, my take is how do we know? We study mid-ocean ridges, which is what you know, the material that comes out at mid-ocean ridges in the middle of every ocean. You know, we study that a lot. I mean, we we can we can get down into these mid-ocean ridges, and so that material then just as it comes out, it gets conveyed, kind of like the grocery conveyor belt where you plop your groceries on and the and you know it goes to the to the cashier to get scanned. That's what happens to this basalt. It gets conveyed away from the mid-ocean ridge, and that's pushing you know the continents around and it's pushing, it's it's plate tectonics, right?
SPEAKER_01Yeah, that's right. And Chris, so so hold on. You you said this is a place that we go to, um, and and that's true. We go to this place, this mid-ocean ridge, which is deep in the ocean but is higher up. It's a ridge at the center. Um, plays things like Elven. Elvin's probably the most famous submersible since the 60s, has been used by uh oceanographic institutes to study this stuff. People go down in these submersibles. Now we send drones, uh drone ones down there. Lots of submersibles down can go grab samples. We also have drilling programs that can go down now and or have for a long time have known have drilled into the seafloor to study the rocks there and taken actually rock samples back up. So there's multiple ways to get rock samples from the modern seafloor, from the actual seafloor. People do this all the time. Every year, there's there's campaigns going out to both place instruments on the seafloor and take samples, take rock samples.
SPEAKER_00Jesse, can I interject? I have a little story about this. I went to I was at this conference once and I went to this lecture. Um, the person was from the Woods Hole Institute, and he was in a submersible going down to study the Mid Ocean Ridge system. But you know, they had all the lights off, right? They have windows in this thing, but they all the lights off to conserve power because this is battery operated. And somebody dropped something, and so they had to quick flick on the lights to find uh whatever was dropped. And they so they flick on the light, pick up what was dropped, and then turn the lights back off. And what they saw was amazing. It was all this bioluminescent biology around the submersible started to light up and responded to the lights from inside the submersible. So cool. And he he was able to show us uh cell phone footage of the the you know, because he started to record it and it just like I don't know, it made the hair on the back of my neck stand up. It was just like so, so cool to see this stuff.
SPEAKER_01I I don't I had a one of my postdoc supervisors went down in Alvin, had the opportunity to go down in Alvin uh to sample, do one of these mid-ocean ridge sampling um campaigns, was on the on the ship for you know three months or something, got to go down got to go down to Alvin for one day. I don't know. I mean, the descriptions were unbelievably cool. I don't know if I could bring myself to do it. I I don't deal with caves or small spaces. I'm not sure if I could like actually you know get into Elven or not and go down, but the descriptions are just unbelievable. So so we collect samples from the modern ocean floor. Before that, and actually what we also use is things called ophiolites. And ophiolites are okay.
SPEAKER_00Hold on, let's spell that a second. That is that's O-P-H-I-O-L-I-T-E. Ophielite.
SPEAKER_01That's right. Ophelite, yeah. And these are oceanic crust, slivers of oceanic crust that have been thrust up onto a continent and are exposed at the surface now. And these things are invaluable pieces of of scientific of rock preservation because basically these are pieces of ancient oceanic crust that have been chucked up on the sea onto the continent, and we can now walk across them. And so there are places like in Oman, there's a very famous one. Up in northern uh northeastern Canada, there's a very famous one. And you actually can walk from the surface. You can walk rocks that were on the surface, where you have a lot of these silicious oozes and things like that. You can walk through pillow basalts, you can walk through sheeted dikes that are below those, you can walk down, and in many places you can actually see the mantle. So you walk through kind of so you can see the gabbro below that, then, right? You can see the gabbro, and then you can walk into the mantle, the depleted mantle, the peridotite that's underneath of seven kilometers of oceanic crust. So in some places, they're really valuable locations because there's not that many of them, but these ophiolites are are really great examples of oceanic crust, just because we can study them better than like a drill, a single drill core or a couple grab samples from Alvin.
SPEAKER_00And if you think about an ophiolite, think about it as a um a host of rocks. This uh where you have this kind of gabbro on the bottom. Yeah, it's a package. Gabbro on the bottom. Well, gabbro and basalt are the same chemical composition, it's just rate of cooling. Gabbro uh never became extrusive, so it cooled slower. You get coarser grain, it's a beautiful, beautiful rock. I love gabbro, but not really that common because most of the time magma that's that fluid will find a way to come out onto the surface. So you get gabbro and then you have these sheeted dikes, which is where the where the basalt squirted through cracks and then became pillow lavas on top where it came out and came into contact with ocean water, and you get these beautiful pillow structures. That sequence of rocks is referred to as an ophiolite. You can see how this might happen, like at a subduction zone, where an oceanic crust is diving down below continental crust, and then slivers of that oceanic crust get kind of jammed up and thrust up on that overriding plate. And that's like you, you know, you talked about this then, you know, millions and millions of years later, you get to walk across this because then it got like elevated and you know, mountains formed, and you get to see these ophelites, you're like, oh my gosh, that means something. That opiolite is we see these, they're in the Himalayas, Jesse. You know, these ophiolite complexes where you had before the subcontinent of India collided with Eurasia, you had an ocean-to-continent convergent boundary. And so when you find these opiolites in a place like that, that marks the suture zone where these two continents were stitched together. That's right.
SPEAKER_01So exactly that's a really valuable, I mean, really cool rock. I mean, uh, exceptionally cool rocks to walk across and great things for studying all things oceanic floor and processes uh operating at the at the ocean floor. So that's uh what are we at? Number three, Chris. We've got two more. We got we gotta come pick it up. We've got a couple more. We did so let let's let's go to I think this might be a kind of a quick one. This is a great question that came to us from Facebook, uh Instagram. What is the most valuable piece of advice either of you have gotten regarding career geology, life, etc.? So why don't you take this first? I'm very curious to hear your answer to this. Yeah, we haven't talked about this. Yeah, I don't think we've ever talked about this, you and I. So what is it and uh and who gave it to you and what was the setting?
SPEAKER_00So I'm gonna go with two answers to this. One is uh just uh from my dad. Um just talking about finding your passion. And it took a while for me to find my passion, and my passion is geoscience. My pa, you know, but I didn't I had no idea until I was sitting in a class with a very gifted professor, and and he sparked my my love of uh geology, all things geoscience. Um and so just follow that passion, and then you know, like just I that's so so so important. That's that's I talked a lot about this with my own children, you know, find what what gets you going and then get after it. Now you gotta do your job.
SPEAKER_01That that's right. I I find this um this piece of advice well it reminds me of of um I think it was Angie Shaw who said this when we interviewed her was do something, pick something you're really interested in because you will work harder than other people at it and therefore be the best at it. And to me, I think this this piece of advice of like find your passion, you can't leave it there. You can't say find your passion, that's it, full stop. You gotta say find your passion, and then go was exactly just saying, go do it, go be the best at it, like go all in, because that's the only way to make a living, right? Or something out of it.
SPEAKER_00Yeah, I I I talk about this. I I find that's kind of to me like grabbing a wolf by the ears. If you find your passion, you know, when you grab a wolf by the ears, you're now you're committed, right? I've I've made the decision to do this, um, and I can't let go because if I let go, I'm gonna get bit, I'm gonna get destroyed, you know. So uh and and passion's that way too. You find it now, man, just you just gotta get after it. So it was that's one. The other one actually was um from Jenny, my wife. I came into when I decided to go into geoscience, um I real I looked at all of the peripheral classes that I had to take, and that's not easy, and it's some of them are just not fun. I had to take calc-based physics, I had to take well, I had to take calculus, then I had to take calc-based physics, and I had to all of this chemistry stuff that I had to do uh didn't excite me. And and I to be quite honest with you, I was intimidated by that. And so I'm looking at this and I'm I'm with Jenny, and and Jenny just said, Well, is is this what you want to do? I'm like, Yeah, yeah, it really is. And she said, Suck it up.
SPEAKER_01I love that.
SPEAKER_00Yeah, that's you know, just that that gets and do it.
SPEAKER_01That gets to the heart of the second of you know, find your passion and then suck it up and do it. Yeah, yeah, yeah.
SPEAKER_00And and that's exactly what she said. And yeah, but that was it was uh, you know, I was actually contemplating not doing this route, not following my passion, because it was a hard route, it was a hard path, and I needed to hear that at the time. It was such a simple thing to say. Suck it up and do it, quit being a baby.
SPEAKER_01Yeah, right. Um and and and so interesting.
SPEAKER_00But that's that's my story. What about you, Jesse? What what happened to you?
SPEAKER_01Uh yeah, well, what happened to me? There's a long question over there. But um, my the most valuable piece of advice I'm gonna this is gonna sound perhaps a little niche at the beginning, but it's been a piece of advice that has served me well in my life and career since since the time. So I was in graduate school, probably a third-year PhD student, maybe fourth year, had had certainly plugged into my my research topic, my my project, and was really excited about it and and you know wanted to continue doing it. And so I was sitting there, we were up in doing field work with just me and my PhD supervisor, Tom Jaco, and we were sitting, we were camping, and so it was one of these nights. I think we were, I don't know, we'd we'd had a long day in the field, we'd come back to camp, had dinner, we were just sitting there, and we were just talking about potential projects and kind of a little bit about what I was gonna do next, basically, postdoc, like where I what I wanted to do, a little bit stuff like that. And I made a comment about like, oh, I would really love to, you know, work at Acosta and answer these other questions. You know, when you do these research projects, you you maybe answer one question and you generate 10 more. And I was talking about those 10 more, right? I was saying, I would really like to do this, this, and this, and and look at this. And and he he kind of he stopped, he turned to me and he said, You're not gonna do that, Jesse. He said, You're gonna go off and do something different. You're not gonna work on Acosta for the next 20 years of your career, you're gonna go do something different, and you have to go do something different. And for me, at the moment, I was kind of like no, or my my instinct was no, or my instinct was that sucks. But in hindsight, it's the best advice because I I went and did a whole bunch of stuff. It just helped me, I think it helped me take my kind of blinders off and open my perspective, and also it's really helped me that that advice. I think about it often because it helps me not hold any one project that I'm doing too close, too close to me, you know what I mean? Like it I don't invest too much of me into one thing necessarily because I'm gonna work in that field for a little bit, and then I'm gonna move on to something else, and other people will come in and work in this field. Other a lot of other people have come and worked on Acosta since I did my PhD there. Um, I don't own that place. They've come up with different ideas, different interpretations. Some I agree with, some I really don't agree with, but it helped me like like kind of let go a little bit of of my expertise and and broaden and build other expertise.
SPEAKER_00So let me ask you this. Do yeah are there people in academia and in the research world that do what you thought you were gonna do? Does that happen frequently? Yeah. Um where they they do one thing their entire research life?
SPEAKER_01There are people who have a a pretty narrow niche who who you know are deep experts in one region, continue working on this one uh series of outcrops or whatever, for for decades, right? That definitely happens. I think other people who are are maybe more um have a bigger breadth are better, um, for some for lack of a better word. Um better's probably the wrong word, but um there are a lot of people who have more breath. And the advice that's generally given is have more breadth. Like don't be that, don't don't study just the one thing because you get your blinders on and you just you can't see the forest for the trees because you're too focused on your hypothesis. And I find this myself with these acos, you know, studying acosta rocks. Whenever I think about new data from there, I always think about it in terms of my work or what I did there or what we're doing there. I I have I'm not I'm not unbiased, I'm very biased when it comes to that. And so it's unhealthy. I just get stuck in a rut thinking about that one region, right? Yeah. Um it's really good to go. And the other the a similar piece of advice has been given where every five to ten years you need to reinvent yourself as a professor. And I really like that. It's like, no, go, go tackle, go into a new field, go do something different, learn a new series of things. It's really healthy to do. And the people who do that I respect a lot.
SPEAKER_00I f I find that to be very, very true. I can I can talk a little bit about that from the standpoint of somebody that's you know on the on the near side of retirement, you know.
SPEAKER_01Well, you've done this every five to ten years. Uh my father did this that you know, pick up some new you're still teaching, you're still in your career, like you're you're you have the same job, but you you modify it internally to yourself a little bit.
SPEAKER_00Well, your motivation becomes different, and it has to be. And I find that I need to be deliberate about that. Why I do things now, the why has to be different because otherwise it just gets stale, it gets old, and that's just not who I am. So, motivation for doing your career, I think, has to change as you move through your career.
SPEAKER_01And especially, Chris, for for those of us in these careers where we might work at one and we often work at one institution for a whole career or a couple institutions, but you have the same job. I mean, a lot of people don't have that. A lot of people change job to job, they change jobs, change roles, get promoted. You and I have these positions that are at a baseline very constant. I could teach the same class for 30 years, and that would get really bad for everybody involved if I did that, right? So you kind of have to internally reinvent yourself a bit. Um, so and I think that applies to to to cre other careers too. Like always be looking for something new and don't hold too tightly to what you've done the last couple years. Like that I th for me that's been very healthy. So hey, that's the answer to that one.
SPEAKER_00Moving on. That's yeah, I think that I think we did that. Well, at least we did it our justice.
SPEAKER_01Yeah, it's a great question. It and it made me think a little bit like what is the one thing that I've been given? So, next question, Chris. This is a tough one. This is this is uh we're gonna work to not get too rambly about this, but um, well, it's kind of short, a short answer, and there's a long answer too. The question comes from Cassie Wallen. Are there any tricks to remembering mineral names? She's studying critical minerals and remembering the mineral names, and composition is rough. So, Chris, when I saw this question, yeah, my response was immediately, no, there are no drakes.
SPEAKER_00No, I what do you do? I don't have any. I I mean I had the same thing. I uh you know, I I've been intimate with these minerals for the better part of my life, you know. Um, and so I I I don't know, I don't. I'm I'm old school, so I memorization is no problem for me, you know.
SPEAKER_01And here's the thing I think you know, for the for like the 10 or 12 minerals that like, for instance, we cover in our Camp Geo content of like the rock forming minerals, the ones you got to know, it's okay to mineral, you can memorize that many, right? Like that's that's pretty so. But when you you talk about dimensions, Cassie mentioned studying critical minerals. When you get into like eudiolite or basinastite and these weird minerals that are rare earth element, fluorocarbonates or whatever. I mean, I got no advice on this one. It is incredibly complicated. So here, Chris, let's walk through this a little bit, kind of two parts to this answer. We're gonna talk about mineral naming conventions, like how minerals are named, and then we have a couple keys to remembering some basic ones at the end. Just the you know, little turns of phrase that I think you found that are really, really good. So, first off, here's how minerals are named. There's uh several different ways that minerals can be named. Okay, first one chemical composition or physical property. That's pretty rare in my experience. Like a chemical composition name is is pretty rare, but it does happen. They but it's not though for groupings, right?
SPEAKER_00We're grouping, yeah. It's like the phosphates and the sulfates and the silicates and things like that, right?
SPEAKER_01When we talk about that, that's a bit easier, but memorizing the you know nim mineral formula is really hard. So, number one, chemical composition. Okay, good. Number two, reasons that have been lost to antiquity. So we don't really know why this mineral has this name. Uh people have referred to this mineral for a long time, and we don't really know why where it started. Okay. Um, number three, which is very common, is named for the locality in which the mineral was first found. So that's pretty common, right? Um, that's the same for rocks. They often have location-based names. It can be named. We can give an example on that. Like the like Andesite is named for the Andes mountain. For the Andes, perfect. So that helps you. I for me, that helps me remember the names, right? Then you can also name it for a prominent person or scientist, uh living or dead. And this is a weird one. You can't name a mineral after yourself, but you can get a mineral named after you. And so I've known I know several people who have minerals named after them. Actually, really close uh PhD supervisor of mine just had a mineral named after him.
SPEAKER_00Um, and so this can be I wonder if we will ever have a rhymingkite.
SPEAKER_01No, then there's there's no Jesseite? Basically zero chance. I think there's a better chance of a bullhead. There's a better chance of a bull high site than there is of a rhymingite. Um but this does happen and this continues to happen as people find new mineral species. They can be named for mythical creatures or deities. Okay, good. That's not helpful in naming. So the ones I'm going through, a scientist, a location, or a mythical creature, those are not helpful for memorizing the mineral names. There's no systematic nature to that. They can also be named by applying a prefix to an existing mineral, right? So that's a little bit simpler, like it kind of gives you a hint, a hint at the the kind of context. So, what are a couple examples, Chris, of of minerals and their naming origin, basically, like where the name come from? That can help us frame this.
SPEAKER_00Yeah. So the first one that jumps to mind is amphible, which is this group of minerals, you know, and horn blend is a very common flavor of an of an amphibole. Um, it comes from the Greek word amphibolos, which means ambiguous, because they're just it looks like a lot of minerals. Like a lot of those. That's perfect. That's not helpful, is it? That is not helpful to hey, this mineral looks like a lot of other stuff, so let's name it after being ambiguous.
SPEAKER_01And actually, let's use the Greek word. And so that doesn't help you memorize it any means, right? Of what it is. That's right. But I do like amphibole ambiguous. That's a really good one. I I really like that. So biotite, another example, named after French physicist, Jean-Baptiste Biot. So biotite, there we go. Doesn't help you understand and memorize what biotite is or the mineral formula for biotite in the slightest.
SPEAKER_00Here's one that does, though, for me anyway, and you kind of ripped on me when we were talking about this, but fluorite. Fluorite is named fluorite because it has fluorescent properties with with the right wavelength of of UV light.
SPEAKER_01So I I ripped on you a little bit because you I think you inverted it a little bit. It's true that fluorite fluorescence are very are intimately related, but fluorite was the first one to get named. Fluorite got named because it's it because of the right flow. And it was fluorite was used as a flux because it has fluorine in it, and fluorine. So fluorine was actually. Actually named after fluorite. Fluorine, the element was named because fluorite, the mineral, has it. And fluorescence actually derives from fluorite as well, because fluorite often fluoresces. So the root of all of this is fluorite to flow because it was used as a flux, which I find that really interesting. And that actually is helpful. Fluorite, fluorine, fluorescence, flux. Like that's all. I actually, that one's one where the name actually the the origin makes sense helps you understand the chemistry and things like that. So that one's pretty useful, I think. Yeah, you're right. I did flip that around, but you know, give me some credit. Give me a case. Yeah, no, you you got it right. I mean, at the end of the day. So, Chris, key keys to remembering some some easy ones. What uh like some minerals? What do you use? This is one I use all the time. Yeah, you how many real quick, how many how many minerals do you make students memorize now? For the or how many do they are they forced to memorize for the exam?
SPEAKER_00Uh I don't make them memorize anything, actually.
SPEAKER_01Or or mineral ID, like is it completely?
SPEAKER_00Yeah, about fifty. About fifty. Um, but I don't make them memorize anything because to me that's just not useful. It's it's not uh what what is useful for me is learn how to do the properties. You can create whatever you want of all, you know, you can have an index card or whatever you want as a cheat sheet for each mineral. You just have to be able to to like run these observations, these physical tests, manipulate the minerals, and determine this is the right mineral.
SPEAKER_01So to identify it. Okay, gotcha. So okay, for that, what do you um what do you tell them for just naming, uh helping make sense of the naming here?
SPEAKER_00Yeah, okay. I got a couple. I mean, obviously, you know, magnetite is magnetic, and we talked about that with the magnetic sand. Oh, yeah, at the top of the episode.
SPEAKER_01Hey, that actually olive easy one to remember. Magnetite, it's magnetic. That's very easy. Yeah, yeah. Okay, good. Nice one.
SPEAKER_00Olivine tends to be olive color, you know, it's it's shades of olive. It can be light, dark, whatever, but uh that's I do use that a lot. And then you know, horn blend Jesse. Hornblende has a really, really, really complicated formula. You know, it's like it's so long.
SPEAKER_01That is the band of most people's existence in in uh the undergrads who have to like memorize mineral formula. Uh hornblend's the one that sucks. Hornblend Termaline are the ones that suck.
SPEAKER_00Yes, they do. And and so you think of like the last part of Hornblend is blend, kind of like a smoothie, and it it's appropriate because of the the length, the blending of all these elements together. Uh I like that one. Okay. I don't know. I don't know. Okay, I like that one.
SPEAKER_01That's all I got, Jesse. That's that's all I got. I like that one. Okay, all right. Those are good. Those are good. I must say I don't have any useful like name formula memorization things, apart from find the ones that that make sense. You know, zircon has zirconium in it, so it's easy to kind of link those together in your mind, right? But um it uh you just you just have to rote memorize memorize these things, I think. There's very few. There are a couple that the names link, so you know, uh fluorofogophlogite is flogopite with fluorine in it, right? That so those ones are I think easy to make sense of and they're kind of obvious. And so knowing the periodic Well, hold on.
SPEAKER_00Flogopite, first of all, is a type of mica, and I think we should establish that. Okay, it's people always think of muscovite and biotite. Phlogopyte is kind of like a brown version of a mica, right?
SPEAKER_01That's right. It's got it's got a bunch of magnesium in it, right? And so this is the one I think of it as the mantle, the mantle mica, basically. Um just because it's magnesium rich, but it's part of a biotite flagopyte series. So yeah, that that's not super helpful because you got to know flagopyte before you know flag fluoroflogopyte. But things like that, those m modic chemical modifications, if you know fluorine, and you and it helps actually me think, okay, so the fluorine's in this mineral, it's got to sit somewhere in the you know, it's in the back of the mineral formula. So so maybe flagopyte has an OHF kind of group at the back side of the formula. Those types of tricks, knowing chemistry, it's just memorization. Memorize the chemistry of the basic minerals, and usually you can kind of infer the other ones a little bit when you start to get into more complicated minerals.
SPEAKER_00Sorry, Cassie. I don't have a clever mnemonic device or mnemonic way of remembering mineral names. I'm just I'm not that clever, so I got nothing for you.
SPEAKER_01No, that's exactly right. I it's a really it's a really tough one, man. I and I and I think with this, this is something I've kind of struggled with a little bit is the critical minerals part is really interesting because the critical minerals are crazy compositions. Like, you know, the the lithium-bearing minerals, minerals that have lithium as a major constituent in their crystal structure are really complicated and they have these weird names. They're not common rock-forming minerals. The rare earth elements are the same, right? They're they're kind of they're very similar in this regard. They're they're like weird minerals that you only run across, you don't learn. The only thing I can say is that a lot of rare earth in the critical minerals world, many of the rare earth-bearing minerals were found and discovered in places like Sweden and Finland and places like that, Greenland. So they often have names that are similar, that are kind of in that linguistic category. So they'll have like unlauts or the AE, the AE um letter in there linked together. I forget what that's called, but they'll have the like words with an unlaut on it, an A with an Unlaut, or things like that. So if you see that, you might think, ooh, this might be a rare thelma mineral because it's probably discovered somewhere in the Nordic countries and it's derived from those languages. So anyway, that's the only uh the only help I could possibly provide. So complicated questions. All right. Memorize flashcards.
SPEAKER_00Yep, I guess. Yeah. Yeah. So this brings us, Jesse, to our last question, which is my favorite. Um, comes from Tim Phobes. I think I'm I hope I'm saying that correctly. Um, Tim, one of your questions we're gonna deal with uh in a later episode. We didn't have time to deal with everything today, uh, which is you dealt with rate of cooling, what we were referring to, you know, when we say fast cooling, you know, was this uh we talk in like seconds with something hitting water, and then what do we mean by saying slow cooling? That's a we'll we'll address that later on, I think, in a in another episode. But we're gonna take on your first question, because you gave us three. Your first question is is it okay to call Jesse Jesse? Or should I call him doctor or professor or doctor professor rhyming? So this is my favorite. I laughed my I laughed really hard when I read this question, because there are so many things that I think we should call Jesse. Um none of them are Dr. Rhyming, right? None of them are Dr. Professor Rhyming.
SPEAKER_01So that's very funny. Chris, we often get we get some when we do get some emails. This this one comes up too. I'm not sure how to refer to you. And actually, you get you get a little, every once in a while, you say people will say, Hey Dr. Ryming and Dr. Bohois, so you get the extra little doctor in there um every once in a while by people. Um, I don't exactly know what to call you.
SPEAKER_00Yeah.
SPEAKER_01All right, Chris, what's your answer to this question?
SPEAKER_00Jesse is fine. That's the way I'm gonna that's the way I'm gonna say it. Um I'm gonna be nice. I'm gonna be nice to my little friend over there that I'm looking at right now. Um Jesse is 100%. He is all right, I'm just gonna be 100% honest. Jesse is one of the least pretentious people that I know. Um, and so it you you do not have to give him a title. It's okay. It's okay. He doesn't he doesn't expect it nor does he require it.
SPEAKER_01That's right. I rarely expect to be called Dr. Radick or Professor Rennick, only very rarely. The only time when it's uh I think it's a little odd when people call me Jesse to start with, is in when I'm teaching like an undergrad class and it's the first time they talk to me, or if you send me an email and um you you you I mean it's fine to send me an email to start with Jesse as a listener, but that that's fine. But when some people come up and say, Oh, hi Jesse, I'm like, uh maybe I uh if you say hi Dr. Remick, I will very quickly say it's Jesse, just Jesse. All the undergrads I insists come with Jesse and graduate students too. So yeah. Although Chris, I don't know. I like director, Dr. Professor Rhyming. That's pretty good if you go with that one.
SPEAKER_00I think oh I know you do. I know you do.
SPEAKER_01Yeah.
SPEAKER_00What to call Jesse? That is the question of the day, right there. Such a good one. It dep well, Tim, it depends upon how I'm feeling in the moment. What to call Jesse. Sometimes I have other things. Other words get used. Other words, yeah, yes, lots of adjectives.
SPEAKER_01All right. Well, hey, Chris, this is a very successful um listener question episode, I think. We're gonna do more in the future. So um send in your questions. We'll uh we'll get to them eventually. We're gonna keep this as a a more regular um occurrence because we get such amazing questions and they lead us spawn. Hey, sometimes we get long valley of caldera questions and we spin out a whole audiobook on a long valley caldera. So that happens, you know what I mean? That's true. Uh that's true. So send us questions. We you can send us questions on our social media, we're at Plangeeocast, our email. Uh, there's a contact us link on our website, planned geocast.com. You can follow this, get this episode, and also all of our other content, including a bunch of visual podcast series with a bunch of images on the Yellowstone National Park, Grand Canyon, Grand Detox, Gettysburg Geology, all sorts of stuff on our Camp Geo Mobile app. First link in your show notes. Check that out. Cheers. Peace.