Only the Strong Survive - Sand

Jesse Reimink: Welcome to planet geo the podcast where we talk about our amazing planet, how it works and why it matters to you.

Chris Bolhuis: Good, good guy.

Nice. Hey you. Yeah,

Jesse Reimink: I can hang

Chris. I can

Chris Bolhuis: I have not, I haven't thrown you a curve ball in a while. Have I?

Jesse Reimink: Chris every day with you is a curve

Chris Bolhuis: I, uh, I know, I understand. How are you doing Dr. Remick?

Jesse Reimink: I'm doing well, Chris, how about you?

Chris Bolhuis: Doing all right. You bet. Hey, it's summertime. it's awesome. Love

Jesse Reimink: could, it could be a lot worse. Let's do some introductions. It's been a while you are Chris. Bohi my former high school earth science geology field, geology teacher. You taught me what? Three classes. I think four classes probably in high

Chris Bolhuis: well, we gotta throw in the independent study because I had so much to do.

Jesse Reimink: Yeah, I was, yeah, I did a. I quote, unquote did a lot on that independent study, but yeah, that counts four classes. you're a nationally recognizer science teacher from the great state of Michigan. You teach a whole bunch of classes, including astronomy, geology, summer field class, which you are probably back from by now. and yeah,

Chris Bolhuis: And you're Dr. Jesse Reimink. you went to hope college to get your undergrad degree in geology. And then you went to the university of Alberta and got your PhD in geoscience. And now you work at Penn state university, one of the most prestigious geology programs in the country, and you teach some classes and you do some research. You do actually a lot of research on really old rocks, right?

Jesse Reimink: Yes, love the old stuff. Old grimy rocks, really ugly ones. Hey, so today, you kind of brought this to the table. You're like, Hey, you know, we should do something on sand. It's really cool. Most people don't pay attention to it. And. I must say, Chris, this was a stroke of genius. This is really

Chris Bolhuis: Let's not go crazy. No, I think so.

Jesse Reimink: yeah. So give us the pitch here, here. Give us the, the sales, the, you know, the elevator pitch for this episode.

Chris Bolhuis: okay. , I really struggle with the pitch though. I don't know, like, honestly, cuz I, I wrote this script for this and, and this was my idea, like you just said, but I didn't sleep well last night knowing that we were gonna record today because I wasn't sure, like how are you gonna react to this? I, I didn't know if you'd like it, the idea or not, but then I don't know. I just, I think sand is awesome. I use it a lot in my classes. Like we have a really long elaborate lab on sand that takes us, it takes us at least a week,

Jesse Reimink: Well, first of all, this gives us a really interesting insight into the dynamics between you and that. Cuz I do the same thing when I'm writing a script. Oh, is Chris gonna like this? Oh, Chris is gonna criticize me for this part, this, this other part. but. Coming from Michigan there's sand dunes everywhere in Michigan. So you kind of know sand, right. But most people, in the world, I think have they know what sand is, but we as geologists have a very specific definition of sand. And so let's just get that out like right away. Let's start with that. And the definition of sand is unconsolidated grains that are. Greater than one 16th of a millimeter and less than two millimeters. So there's a very narrow, well, it's not super narrow, but a very specific size designation for sand.

Chris Bolhuis: that's right. And below that, if it's smaller than a one 16th of a millimeter, we call that silt. And then one step below that smaller than silt, we call that clay, which is comparable to dust sized pieces or, fragments. Okay. Above it above two millimeters, we call that just gravel. I mean, we, right. Is that good enough? We don't need to get into. The nuances of

classifying this stuff,

Jesse Reimink: no,

Chris Bolhuis: So we're talking about a grain of sand that fits in between that, parameter there. And that's actually quite heavy, terms of the way that sand is moved by running water usually then, it's too heavy to often be carried in suspension. In the middle of the column of water.

Jesse Reimink: That's a really important point. Chris sand is a high energy thing. I mean, wind can blow sand, but it can't really pick it up like dust. You can have dust storms where, dust is carried really high up sand doesn't ever make it up that far. When wind blows sand in sand dunes, you know, if you're walking a sand dun it's really windy day, you can usually feel sand, like hitting you in the foot or the ankle, maybe, maybe in your shin, but not much higher. Right. Cuz sand doesn't actually blow up that much higher. It can't carry it. The same goes for water as you're describing. Right.

Chris Bolhuis: that's right. Hey, we need to back up though. Cuz we jumped right into it. I don't think we did a good enough job of like why in the hell are we gonna spend this episode and talk about sand? I think everybody out there is probably like what really they're gonna talk about sand. sand is amazing like it, if you look at it under a microscope, The world just blows up. I mean, it's, it's absolutely amazing. And what you can learn about sand, the minerals that are in it, the sorting that it has the angularity or rounding of the clasts or pieces, you can determine a ton about. The sand where it came from, how far it, went. Um, what the energy of deposition was. I mean, there's just really a lot that you can do. The whole world just comes kind of comes alive.

Jesse Reimink: And sand is not one thing. Sand is really diverse. There can be individual mineral grains, they can be quarts or other mineral grains. They can be rock fragments. They can actually be Biogen. They can be classs of fossils or shells that are in sand. so there are lots of different types of sand out there and they all tell us something very specific about the geological environment that, that sand was created and deposited.

Chris Bolhuis: in my intro and the intro that you gave for me, you've talked about my geology class. And, uh, so it's a bunch of high school juniors and seniors. And every year we do a, what is called the sand lab and I get really excited about it. Cause I think it's cool. I have,

Jesse Reimink: Chris, you get really excited about everything. So let you know,

Chris Bolhuis: Well, that's, that's true. I, I'm not gonna deny that, but I have eight different samples of sand that I've prepared. I put 'em on these clear plastic dishes. We've brushed out the microscopes and we look at the sand and, I ask like kind of leading questions. Right. And, and they come to conclusions based on what they see and all it's, it's really neat. But I also ask my students, Hey, if you go somewhere. Bring me back a bag full of sand. You just need a Ziploc, and bring it to me. And we'll write on there with a Sharpie where it came from, , who brought it in the date on it. And so on. I don't know. I probably have, over the years, I've collected 250 to 300 different samples of sand from students, uh, over, over the whole world. I mean, I have a student that went to Iraq. Um, he was in the army and he brought me back a Ziploc full of sand from downtown Baghdad. You know, it's just, I've, it's, it's all over the place. And, and so when I, it is, it's really cool. So we use it,

Jesse Reimink: So one thing that we just started touching on as we were building the script and it kind of shocked me is that sand is really important to society in a way that I had no idea about before this. So this is a massive industry, sand mining and sand uses. And I guess upon reflection, it makes some sense, but as a society we use. 40 pounds of sand per person per day, just in the society.

Chris Bolhuis: Okay. Hey, when you first said that I'm like, No that prove it. prove it. Like we ,we've delayed our recording so we could talk about this. And, and we had to verify that that is the case. How in the hell Jesse, are we using that much sand what are the uses? How's this

Jesse Reimink: Yeah. Yeah. It's kind of amazing. So that, that equates to 50 billion tons per year, more or less. And that continues to grow very rapidly because concrete is made up of about 25% sand. So concrete is the main. User of, of sand actually. And it's actually a very specific type of sand that they're after the concrete industry. So we'll come back to that. I think at the end, Michigan, our home state is the number three sand producer in the us. And part of that is because there's a lot of sand deposits, but also it's because the auto industry, they use sand for casting. Metal parts for the auto industry and it's used in ceramics a lot. It's also used in the fracking industry. So in hydrocarbon fracking, you drill down into a shale. Does not allow the oil , and natural gas in there to get out, cuz it's impermeable, you frack it, pressurize it, and you create these cracks, but those cracks need to be held open with something so that you inject sand into those cracks to hold it open. And the sand is porous and permeable allows the hydrocarbons to flow out. So

Chris Bolhuis: That's right. It kind of props those cracks open it's it's called a prop and it's like, you know, opening a door and the door slams shut. That's what would happen to shale if we just fracked it and didn't use sand. So we gotta open the door and put a rock in the place to prop the door open. And that's what the sand

Jesse Reimink: Oh, that's a great analogy. Wow. That's a perfect analogy right there. So just to put this into, you know, a little bit context, it takes 18, roughly 18,000 tons of sand to build a mile of highway, which. Is amazing 200 tons to build an average single family house. And this means this is kind of amazing. So to put that 50 billion tons of sand into context, that equates to 40 pounds of sand per person per day. unbelievable. 7 billion people or however many. There are now 40 pounds per person per day is unbelievable. That would be a wall around the planet. 27 meters high by 27 meters. All the way around

Chris Bolhuis: Oh, my gosh.

Jesse Reimink: It's an incredible amount of

Chris Bolhuis: like it is. Um, yeah, so I don't really feel good right now. Um, not seriously, uh, you know, 50 billion tons of. That we use annually. That's the same amount of greenhouse gases that we put into the atmosphere by mass. Okay. 50 billion tons, every single year. Sand is actually the second most important resource behind water. It's the Second. Most used resource?

Jesse Reimink: exactly. Yeah.

Chris Bolhuis: That's crazy.

Jesse Reimink: That's unbelievable. Unbelievable.

Chris Bolhuis: and if you want to go back and listen to our episode on water and like this kind of water crises, we have an episode in season one that deals specifically with this, because this is again, a huge, huge issue that humanity's facing.

Jesse Reimink: Sand is very much the same way we are facing a crisis here. Much of that sand, much of that 50 billion tons per year is not mined in a sustainable ethical manner. And. There's a, a problem and there's a growing problem and it needs to be fixed. So it's something that we should all be paying attention to. And we're not gonna get into that too much anymore, Chris, cuz you're right. It's a little bit scary and a little bit outside our breath, cuz we should talk to some mining experts in sand. That would be very interesting. But we're gonna talk about the, geology of it and like how does

it

Chris Bolhuis: Hey,

Jesse Reimink: the different types?

Chris Bolhuis: sorry. I want to interject Jesse. so I'm looking at something here that you actually put in the script that you said the 50 billion tons that we use a year, , most is coming from rivers and inland lakes. , and that desert sand and ocean sand is too rounded to be used in concrete or fracking. Why is that? Do you.

Jesse Reimink: So the. Desert sand in ocean sand. You can think of this as it's being blown around all the time. So in the desert that sand is being blown back and forth. It gets really rounded and it gets made smaller. And the same goes in the ocean. You know, that sand on the beautiful white Sandy beaches, that's being washed up and down, up and down, up and down. Whereas a river comes in it dumps sand during a flood stage, and then that sand just kind of sits there. So it, gets transported a little bit. Sometimes a long ways, but it doesn't get rounded to the degree that desert sand

Chris Bolhuis: but I don't see how, what that matters. What, who the hell cares, whether it's rounded or angular. Uh, how

Jesse Reimink: what you're saying. So the surface roughness is really important for like concrete. It's the binding, how well it binds to other stuff, really round smooth stuff is not very good at binding or for fracking, not very great at propping open rock, crack. So you so that's really what we're after. So exactly. Exactly. So. Sand is really important as we've highlighted. So let's get into some of the details about the different types of sand, cuz there's a lot of different sand out there and it's formed in a bunch of different ways, which means. When we look at the rock record, we can look at a sandstone and sandstones all can be very different. And we can look at the sandstone, look at the sand and say, what kind of environment existed on earth when that sand was being deposited. So where do we start, Chris?

Chris Bolhuis: one of my favorite things to do when I. Students out in the field is to bring like these field microscopes put 'em together right out there in the field and look at sand. And then, alright, what can we determine about this? What's so not only is sand really, really, really important. It's also very cool. you said, where does it come from? Right. where does sand come from? How does sand form sand comes from the chemical and physical weathering of rocks? And then we've talked about this before, chemical and physical weather, and it's been a part of our episodes we haven't done like a specific episode on that, but we've done, done it in context. Right. What do you think is the most important process in terms of forming sand? Do you think it's the physical weathering or the chemical weathering? What do you think?

Jesse Reimink: I mean, this was a hard one for me. I talked about it before. I it's like unclear. I think both are important because the physical breaks down the rocks and then the chemical kind of helps to sort them a little bit. So I'm not which, which one would you say Chris?

Chris Bolhuis: I would say definitely chemical and there's a thought process that's involved in, this like answer. First of all, what is the most common rock that is continental and origin? What, what is the rock made of? What's continental crust made

Jesse Reimink: grant.

Chris Bolhuis: and granite is loaded with. Okay. Now, most sand , it's derived from soil. So you get this veneer of soil that forms over the rocks. Okay. And it's being chemically broken down. It's being physically broken down. But the thing is why did I pick chemical weather and is the most important process because what happens to Felds bar with chemical weather? What does Felds bar turn into

Jesse Reimink: Phelps bar really easily goes to clays.

Chris Bolhuis: that's right.

Jesse Reimink: And

so it gets broken down. Yeah.

Chris Bolhuis: Yeah. So the Feld spars actually change into a different mineral. and that gets carried away. Now what this does though, is it frees up the quarts that's in the granite.

Jesse Reimink: mm-hmm

Chris Bolhuis: Okay.

So not only did the feldspar change composition become a different mineral. The quartz now is loosened up free from its matrix and now can be moved. Now the physical aspects of it come into play, but it wouldn't have happened that way. If it hadn't been for the chemical weathering, that's why I kind of think that's why I go with chemical weathering being the most dominant process.

Jesse Reimink: makes complete sense, Chris, and really you're talking about sort of take a rock. It has a whole bunch of different minerals in it. The chemical weathering. Wears down a whole bunch of the minerals and leaves some behind. So we're left with this. Like skelet, if you took a granite, you just let it chemically erode really aggressive chemical erosion. the quarts would be the only one that's left. So that's a great analogy. I really like that, Chris, that's a, that's a good one. And then this transport, , the physical weathering, once it's broken apart, and once you have this sort of chemical separation, then the physical weathering takes over. And so. It's important to point out that felt spars breaking down and turning into clays. It's not just felt bar that chemically weathers quickly, most other minerals in the rock actually do the same thing. Olives, puric scenes anals Mica's. Most of them will break down and turn into different clay minerals or different other minerals that are lower temperature. And so. basically quartz is the only one that doesn't. And so if we look at a sand where we have quartz grains, plus other stuff, quartz and Feltz bar, and maybe some Amal in there, kind of a dirty sand, what we would call dirty, quote unquote, what does that tell us about the source of the sand? The rock from where the sand originally was?

Chris Bolhuis: so the title of this episode, Sand only the strong survive. Right. And you said it that quarts, nothing really happens to courts. Quarts can get broken down into smaller and smaller and smaller pieces, but really it's, a very stable mineral, whereas all the other common minerals are not nearly as stable. So if you have a. A sand that you just described that has a bunch of other stuff in it. It's got some quarts in it. It's got Felds barn in it. It's got, some horn blend in it and all these other things. That's an immature sand. In other words, the source of that sand is not very far away

Jesse Reimink: Absolutely. So that means that there hasn't been enough time. Time is distance here during weathering. So if you have a river, that's right at the base of a mountain and the mountain is all the granite, that river is probably gonna have quarts and felt spar and a ball and stuff in the sand. That you grab in the bottom of that river. Now, if that river is like the Mississippi thousands of miles away from the mountain, it's probably not gonna have Phelps bar and a bowl. It's just gonna have quartz for the most part in a bunch of clay minerals in it, maybe, but we're talking about sand size grains. So the sand is gonna be mostly quart sand. So it tells you how far cuz time is distance, distance equals time for this weathering process. Uh, so farther away is more chemically weathered and actually more physically weathered as well, which means that. The grains we are looking at will be more rounded. The further they travel, the more rounded they become. And this is really easy to imagine. Think of your sand grain. It's just bouncing along the bottom of the river bed. Every bounce has the potential to knock off any sharp edges. So more of those bounces means you get more and more rounded, really tiny little beads of quarts when you're really far away from the source, if you're really close to it, there might be more edges.

Chris Bolhuis: And so those two things together, line up to tell you a lot about where the sand came from. Right round. Long ways. And the more pure the sand sample is, it doesn't have a lot of other stuff in, it came also from a long ways. So\ rounding and this kind of, it's sorting, right? I mean, this is a term that I don't know. I use it. You use this term a lot in, in your, you know, intro geoscience classes, Jesse sorting? Sort of, Yeah. You know, it's like if I gave you or I gave anyone a jar full of Skittles, which, you know, I love Skittles. It's one of my favorite candies.

Jesse Reimink: you do.

Chris Bolhuis: just love 'em. They're so good. Um, anyone you give, 'em a jar full of Skittles, they sort about, they know what to do. Right. You're gonna sort it according to color, you know, five different piles and there you go. Right. But that's one way of looking at sorting is like, The different colors, equal different minerals, right. so if you have a well sorted sample, that means it's only gonna have mostly one color and maybe a couple of other colors sprinkled in there. Right, But if I gave you Skittles that, , are different sizes and said, now sort these out again, you know exactly what to. and so sorting can mean mineral content and it can also mean mineral grain size or the density of the minerals. They're all gonna be deposited in the same kind of environment. So what are you grinning about? You're

Jesse Reimink: I'm just picturing you. I, I can't get over the image I have in my head of Chris. I sitting on his porch on a hot summer day. Just a handful of jar Skittles. You got sticky, colorful fingers, just chomping away at your Skittles. I call you sticky now on

Chris Bolhuis: that's

Jesse Reimink: a good nickname. but, but, it's a, it's a.

Chris Bolhuis: call me that.

Jesse Reimink: Okay. Alright. Well, it's a really good analogy. The, that this sorting. Yeah. I use sorting all the time in class. I mean, it, this is a classic, like sedimentological, , process that the further away from a source for the most part, the more weathered and the more rounded these grains sort of get.

Chris Bolhuis: And water is really, really good at sorting minerals out. Right? It's very discriminating glaciers. They don't do that. Glaciers don't care. They don't have to discriminate according to mass or size or all that kind of stuff, but water does, it can only carry what it's capable of carrying.

Jesse Reimink: And we use water in our lab to separate out zircons from quarts and pals bar and all these things. So we use water. It's basically like what we call it. A water table. It's think of gold, panning gold panning is using water to density sort and size sort. We do the same thing in the lab rivers do the same thing naturally.

Chris Bolhuis: Question. Most people are familiar with the, minerals. Muscoy and biotech. They're the two common ones. Right? What do you think those minerals, first of all, Jesse, describe what they look like a minute. And I'm gonna ask the question.

Jesse Reimink: Mu cite and Micah. Yeah, they're little tiny flakes. Very, very, very thin flat flakes. So actually Muscoy, if it's a big piece of musky, it's flat, you can peel the layers off. And that, that small form is very small. Flaky has little shiny edges to it.

Chris Bolhuis: If you have ever taken an earth science or geoscience class you've seen and held probably Muscoy and bioTE in your hands and you can't resist the urge to peel 'em into their thin little sheets. right. My students just destroy it all the time. So would you expect to find mu cyte or bioTE in a well sorted, rounded sample of.

Jesse Reimink: No, you would not. And the reason is. That behaves very differently in water, right? rounded quartz grain is gonna be bounced along the, the surface. And it has a certain density to it. Mu cite is actually much less dense and it has this flat pattern. So it'll kind of float in the breeze a little bit more if you will, as it's going down the river system, so it could get carried. In much lower energy water than a quartz grain can. And so you kind of wash all that stuff off of the quarts and what's left behind are these quartz grains that are kind of dense and kind of bounce around on the surface. So this is this sorting phenomenon that, that you end up getting. so Chris, we've been focusing a lot on courts and, you know, really focusing on courts, which as you can imagine makes up really white Sandy beaches for the most part. But everybody is probably familiar with black Sandy beaches. You see these pictures on Instagram or online black or green Sandy beaches, you know, those are different minerals. And so how do we generate those types of beaches that have different sand, not quart sand in them? have to address that. I think.

Chris Bolhuis: so first of all, when you have black sand or green sand to, us that right away signifies, this is MEIC in composition. This is these minerals. The whatever's making this stuff up is gonna be rich in iron and magnesium. That's what tells us. So whenever you see this, these are usually beaches that are derived in a volcanic setting, but. It's not just any kind of vulcanism, it's like the may kind of Hawaiian type vulcanism that I think most people are used to seeing. So, and the reason is because like Mafi magma, if you go back to our episode on Bowen's reaction series, these experiments. We're really designed to explain why certain minerals only occur with other minerals. And, and really what we're saying is minerals like the really dark colored minerals, Aine, calcium merch, PLA place, uh, purine, these minerals, they don't often occur or they don't occur with quarts. Okay. So if you have Mak mag. You don't have a lot of courts, so you're not, you can, you can transport this a long ways and you're still not gonna get quarts. Right. You're gonna get, you're gonna get something that's reflective of what the parent material was. The proli.

Jesse Reimink: That's exactly right Chris and those beaches. So black sand would be mostly little fragments of basalt or maybe black pyroxenes in there. Green Sandy beaches would be mostly olivine. The mineral Aine, where a beach is, you know, mostly sand size grains of Aine. And the G gala islands, I've been to the Glo coast islands and there are some Blackish, Sandy beaches and some greenish ones. There's also these really interesting red ones and the red ones are. Basically this dark iron rich basalt that gets weathered. And so you get little pieces of basalt, but then those get oxidized. So the iron rusts basically. So you get this dark reddish Blackish sand, which is the basalt. And I remember there's this, there's this little Imus, like little peninsula coming off of one of the islands where one side of this really narrow it's like, you know, Maybe 70 to 80 feet, wide beach with a little dune in the middle. Right. And it's a couple hundred feet long or something like that. And on one side of the beach, it's black, or this Blackish red, the other side of the beach, it's white. And this was really interesting because the reason is because the black side, that's all volcanic. Pieces pieces of volcanic rocks that form the black, the white side is actually shell fragments. And the reason that they were there was cuz the wind direction was blowing inland from there. And so it was blowing all the shells and broken down organism bits inland and blowing it up onto the beach, which made this white Sandy beach on the other side where the wind was blowing offshore. Mostly it blew all the shell fragments out into the deep sea. And so it's just a good example of. The beaches really reflect. the geology of that area. They can tell you, oh, the wind was blowing, you know, dead creatures back up onto the beach. And on the other side they weren't, and it's all volcanic sand. So, these types of sands, a lot of these volcanic sand, black and green, well, they're not common. The reason they're not common is because this chemical weathering process breaks them down really easily. So one single sand grain on those black beaches will not be around for a long time. It'll get chemically weathered pretty quickly. So they have to be replenished a lot, whereas a pure quart Sandy beach that sand grain could be moved up and down around for years and years and years breaking down too much.

Chris Bolhuis: it won't break down. You're right. It won't break down. But if the wind direction is wrong, it can take that quart sand that was deposited and blow it into the lake or into the ocean. And then you're back to square one. If you want the beach, you have to replenish it. But I do wanna talk about like Hawaii, for instance, we're talking about an island nation of black rock, so do they have any natural beaches? Natural means not imported sand. How would it be possible to have natural beaches that are more white, more normal looking beaches? Like what you just described?

Jesse Reimink: yeah. So these beaches are mostly gonna be shell fragments, you know, carbonate pieces of carbonate, and you could get both old shell fragments and also the carbonate reef parts and sort of chemical deposition of carbonates in these shallow laal settings that get kind of blown up. You can get carbonate mud that gets bigger and bigger grain sizes. So it's either biochemical or. Deposition of carbonate and that gets blown up and made into this white Sandy beach. So yeah, that's absolutely to, to do this.

Chris Bolhuis: That's right. And the other thing is back in the early part of the 19 hundreds, Hawaii started importing sand, like literally by the shipload, , and dropping it off because, people are accustomed to white touristy looking, typical beaches, you know, so they have that too, but that's a constant, project that needs to be revisited again and again and again, through beach nourishment, because the wind blows the sand and the erosion takes it away and off it goes.

Jesse Reimink: So Chris, the other type of sand that we've talked about briefly before was lithic fragments or rock fragments. So this is sand that, , actually, if you picked it up and looked at it under your field microscope, you'd see that each little grain has a whole bunch of different mineral grains as a part of it, it's actually a miniature rock. So it's a small piece of rock that is made of multiple different minerals. And you see this in places like. And the, the Japanese beaches, a lot of them are lithic fragments. , because the volcano is right there. You have a volcano that's making new rock. That rock is broken down. It forms the beaches. You can see this off the coast of Oregon and up in British Columbia as well. And so the thing is, is these are what we call immature. You're so close to the source rock. It's literally, you can see the volcano and the volcano is being broken down and depositing it. Cuz those lithic fragments, they break down really easily. So it's very easy to take one of those little sand grains and sometimes you can do it between your fingernails and crush it and break it into the three or four different mineral grains that make it up.

Chris Bolhuis: do it between my fingernails, but I don't think you could.

Jesse Reimink: no, you're probably right. I probably couldn't. become a little bit of a weakling need to get out there in the field and do some smashing of again.

Chris Bolhuis: professor hands. You

Jesse Reimink: That's right.

Chris Bolhuis: professor hands

Jesse Reimink: right. I stick to my lab, work, fixing machines and stuff. You know, it's not, not nearly as bad ass as breaking rocks. But they're easy to break down. And so they won't last long, again, just like Aine beaches or the black beach. Those grains don't last very long. So they're quote unquote immature. And if we take this style of thinking, we're talking about a very modern earth oh, there's the volcano then there's lithic fragments. Great. how does this carry back into the rock record, Chris? When we look at old rocks, do we see evidence of this, the same kind of process?

Chris Bolhuis: Yeah. One of my, favorite places to take students, , on like , an intro to Pierce's geology in the field is pictured rocks, national lake shore in the upper peninsula of Michigan. It's on the lake superior side. one of the cool things about it in this beautifully, layered sandstones got lots of cross bedding in it, lots of sedimentary structures and so on. It has Garnet almondine Garnet minerals in it, in the sandstone. And that's important because. That tells us that the Garnet is like a, you can trace it back to its source. Where did these minerals come from? And they came actually from the Canadian shield. And so we know the source of where the sediment was coming from, where it was. Transported and then where it was deposited. , so stuff like that, the mineraly of old sand that turned into sandstone can tell us a lot about the geologic history of that area.

Jesse Reimink:

Yeah. And Chris, this is something that people do all the time. To study ancient sedimentary rocks. So there's quarts a lot in these ancient sandstones. There's also zircon and zircon is of mineral I'm particularly interested in cuz it's great for endocrinology. We can analyze individual Zeon grains. They're very resistant. They're as resistant, if not more resistant than quarts and they occur in granites in intermediate rock. But they're very small percentages. Like quartz is very abundant. 40% of the rock. Xons like far less than 1% of the rock. So little tiny grains, but they get included in these sandstones. And so we can go pick up ancient sandstones, look at the zircon and analyze a whole bunch of the different zircon and tell the age of the crust that was being eroded into. The sand that then formed the sandstone. So we can kind of do this sort of tracing, like you described with, the garnets, we could do this sort of, you know, I don't know what it's called genetic tracing of the sandstone and say, oh, what was eroding into this basin? And people do

Chris Bolhuis: that's exactly what I was gonna call it. Yeah. and it's important also to note that when you do that, you're dating the age of the grain. You're not dating the formation of that sedimentary rock or when it was deposited as sand you're, you're going for something else. You're, You're,

going back to the source material. So, yeah.

Jesse Reimink: Right, exactly. Right.

Chris Bolhuis: All right. Well, Jesse, I think we're, we're getting close to wrapping this whole thing up here, but I wanna , just for a summary standpoint, stand forms from three different broad sources, right? It forms from individual minerals. It can form from lithic rock fragment. and it can also form biologically like, you know, calcium carbonate, , organisms that lived and they died and their shells got, blown up onto the beach and that kind of thing. So I want to just use that last one, the Biogen sand, as an example of something that I do in my classes, when I have this, sand lab, first of all, looking. A Biogen sand underneath a microscope is absolutely amazing looking at the, the, the diverse colors and the, the patterns that they have on their shells. And keep in mind too. This is calcium carbonate, which is the same mineral as calcite. So it's pretty soft, right? So Biogen sand is really, really, really smooth and round. Okay. The shell fragments, the edges and corners round off a lot with this because of the softness of it. . But I have a, couple samples from this place that I love in South Carolina. It's called Edo island and two sand samples from the same beach. One of the samples has all Biogen, all shells, very little sand in it, And I say sand, I'm talking about grains of quarts in it. It's all shells. Then the other one from the same beach has maybe a 50, 50 split shells and Deri grains. You know, grains of quarts. This is like, , how could this be? What, you know, this is one of the things that I want my students to, to like, begin to understand. Well, where does the Biogen sand come from? And I'm asking you, like, where, where would that come

Jesse Reimink: So it'll come from the ocean, the organisms in the.

Chris Bolhuis: Where would Therial quartz grains?

Jesse Reimink: They would come from presumably the mountains nearby or the rivers bringing those from insure they're being deposited into the beach from ins.

Chris Bolhuis: They're coming from rivers, right? So , how would you have on the same beach then a sample taken two different locations. One that has no Deri cord screens in it, and one that has a lot of it in it. Well, like what kind of conclusion can you make from that?

Jesse Reimink: Well, I would probably say that these are two different times of beach deposition. One where a river, maybe a big flood happened and it deposited a whole bunch of sand into that beach environment. and, you know, brought more to TRID grains into the system, whereas the Biogen sand was sort of always being deposited there in the background. Would that be a assumption, Chris?

Chris Bolhuis: Yeah. I, I'm not talking about a vertical, like, you know, one on top of another, there are two different lateral locations but you're right. It has to do with proximity to a river, right? , the sand that had the Coch grains in it was taken very close to the mouth of a. Whereas the sand that had no quarts in it, , we were just walking on the beach for miles and we were a long ways away from any mouth of a river, any, source for, that kind of sediment. And so it was just nothing but Biogen sand. So it's like, I don't know. I just love that kind of stuff where you can make conclusions that are pretty simple. They're not very complicated, but they tell a lot,

Jesse Reimink: Yeah, they tell a heck of a lot. That's a great one and a great way to kind of summarize the variability that you get in sand, even from one beach. And we've talked about how much variability there is in sand, around the world in different locations, in different geological provinces. And I just kind of want to come back to the importance of sand here and say that, you know, a lot. Mining that we talked about. Mining of sand, people were interested in industrial uses of sand are interested not in sand from deserts because that's getting blown around and reworked and smoothed out. And again, not in sand from oceans because that's kind of doing the same thing in the beach environment, but rivers move a lot of sand. Because they're this perfect grain size to be moved by water bounced along the river in the bottom in normal times, and then carried in a large quantity during a flood. So rivers and lakes are very important for sand, given the, energy that it requires to move sand a little bit. So sand's important. Sand's interesting. Uh, what if this was really fun, Chris? Great idea. . It's stroke. A genius. I'll I'll say it .it . was awesome.

Chris Bolhuis: go that far. I don't know if it was a stroke of genius, but I, I don't know. I

Jesse Reimink: Really fun to talk about sand super important. And it tells a lot sand's not boring. Just like geoscience rocks are not boring. Sand is amazing.

Chris Bolhuis: Well, it's, you know, here's, here's a thought, right? That you, you take a, just a simple thing of, Hey, let's take a bunch of different sand from a bunch of different places. Let's throw it under a microscope and let's see what we can deduce. Right? This is how geologists think. And I think it makes us a little bit different. Don't you? Like, we think about things a little bit differently. We have a, a skill set that I think we have to develop as we live our lives, thinking, looking through the world through the lens of a geologist, you know, I don't know.

Am I wrong on

Jesse Reimink: no, you're right. I've talked to several, um, you know, employers who hire end up hiring geoscientists, both in geoscience fields, geoscience, adjacent fields, and in different fields, like venture capital. , and they. Are of the opinion that geoscientists have a different style of thinking. You're exactly right. It's very observational. It's very data rich. And we have to think in four dimensions, we think in these huge time scales and huge length scales, but also we have to think about time. We have to think, oh, how does a tectonic plate deform and move, but then how does it do that over millions of years? It's a very visual and, sort of complicated three or four dimensional field and things that are ultimately underpinned by very simple observations at the end of the day, which makes it really fun. Very very, very fun. And you get to picture, you know, oh, there's Garnet in the sand or you get to picture like what an ancient sand beach looked like when it was eroding from the Canadian shield. I mean, really cool. Just amazing stuff. sand is great. Well, I think that's a wrap, Chris, and, uh, you can follow us all the social medias we're at planet geo cast. Send us an email planet, geo cast, gmail.com. Give us a like or subscribe and a review. The reviews in particular, really help the algorithm and make us more discoverable. And we really appreciate that.

Chris Bolhuis: That's right. We also appreciate it when people share our podcast with people that you think would like it.

Jesse Reimink: Absolutely love that. All right.

Chris Bolhuis: Yeah. Cheers.