Dr. Jesse Reimink: So I, you, so, you [00:01:00] know, my dear wife knows that I hate Geology puns and this is a very Geology pun shirt. And every year for my birthday, she gets me a Geology Pun shirt. And that was yesterday. So, this shirt is a birthday shirt from her that I had to wear all day yesterday.

It's actually kind of a good one though, because it actually. has educational value a little bit like usually Geology puns are like, oh, nice schist or whatever, you know, something stupid like that. This one's like

Chris Bolhuis: You know what, you

Dr. Jesse Reimink: a fault in pressure.

Chris Bolhuis: one of [00:01:30] mine. That is a good one,

like that nice one. I like the, the one that says Nice church.

Dr. Jesse Reimink: Uh, but still there's no connection to it. It's just kind of stupid. there's no linking of the geological ideas. This is, this one says a fault. It ruptures because of the pressure. That to me is, is kind of nice.

Chris Bolhuis: ones I've seen. I like it.

Dr. Jesse Reimink: Yeah.

Chris Bolhuis: too.

Dr. Jesse Reimink: it's very colorful,

Chris Bolhuis: Like it's busting with

Dr. Jesse Reimink: very bright.

Stands out in the crowd.

Chris Bolhuis: Well, you already stand out [00:02:00] in a crowd. You big giant,

Dr. Jesse Reimink: it's true.

Chris Bolhuis: don't, you don't need all

Dr. Jesse Reimink: Now I'm wearing this

extra large shirt that's very brightly colored that says it's, it's my fault. what else am I fired up about? Oh, uh, well, just more publication stuff. I, we had a publication re, uh, rejected again, uh,

morning. So it's just a frustrating thing to wake up to.

Chris Bolhuis: Send me the names.

Dr. Jesse Reimink: Okay, we're, gonna go out and bust some heads for this.

Chris Bolhuis: You're right.

on [00:02:30] my guy. Uhuh Uhuh.

Dr. Jesse Reimink: You know what's funny? that was my wife's response too. I woke up this morning and I was just cranky. 'cause you know, these emails inevitably come in at like 3:00 AM or something. Right. So my grad student, who's the lead author, farted it to me.

And, uh, I was just in a. Cranky mood because of this this morning, and anyway. And she, she did the same thing. She got into real attack mode. Like, screw these people. Who should we, who should we go talk to about this? You know?

Chris Bolhuis: Yeah, I'm, well, I'm not gonna do any talking, Jesse. I'm gonna bust some heads, like you said here. I'm gonna [00:03:00] take care of business.

don't mess with my people,

Dr. Jesse Reimink: mess with my team, man. I love it. I love it.

Chris Bolhuis: Um.

There was something else that I wanted to ask you about. So tell me about the misspelling though. How did that happen?

Dr. Jesse Reimink: I have no idea. I think she, this shirt, the, the couldn't with a no LI think, I don't know if it's meant to be that way or if, you know this is just a shirt she found in some random corner of the internet, uh, made by people who don't know how to spell. Couldn't for some reason. I don't know. I don't know if it's [00:03:30] intentional or not.

I don't really know where she finds these ridiculous, complicated, punny shirts, but she's managed for like eight years to get one, a new one every year.

Chris Bolhuis: I have one that says, never help a geologist move.

Dr. Jesse Reimink: that's a good one. I like that one. I saw something.

Chris Bolhuis: And it's got a bunch

piles of box piles, you know, and they're all just full of rocks. So,

Dr. Jesse Reimink: Yeah, I think that's a, that's a really good end. I, um, I had one recently, well, I've seen this before, but there's this, uh, I [00:04:00] think it's like a, you know, newspaper, cartoon one person says, oh, I'm a geologist. And the other person says, oh, that's not a real thing.

That's just alcohol and guessing.

Chris Bolhuis: That's, that's pretty

Dr. Jesse Reimink: It's famous among Geology circles. I saw that again the other day. I was like, that's quite a good, inaccurate but funny.

Chris Bolhuis: It's It's, um,

Dr. Jesse Reimink: Anyway. How, how are you?

Chris Bolhuis: on a minute though. I feel, I feel really bad a minute. yesterday was your birthday?

Dr. Jesse Reimink: That, that's [00:04:30] the last reason I'm worked up, Chris, is I,

Chris Bolhuis: I am a bad friend. Oh my gosh. Are you serious?

Dr. Jesse Reimink: but it's okay. It's to the point. We don't celebrate the number anymore, so, you know,

Chris Bolhuis: Well, I know, I know all about that. I I totally get that. But still, I mean, I, I could've at least texted you and said some snide remark about whatever, and recognized your birthday

Dr. Jesse Reimink: uh, it's okay.

Chris Bolhuis: you are a funny guy though. You have no social media presence at all.

Dr. Jesse Reimink: I try and avoid it.

Chris Bolhuis: just,

do.

I don't get any [00:05:00] reminders about, Hey,

Jesse's birthday or anything like that. Right. So I guess as soon as we're done here, I have to just put it in my phone as a recurring

Dr. Jesse Reimink: You know, that's what I've taken to, to be doing because

Chris Bolhuis: Andy call you?

Dr. Jesse Reimink: we played phone tag yesterday and uh, we talked this morning. So,

but you know, the family, the family's really all that matters for this purposes.

But, um, so Chris, how are you doing? I mean, it's not about you. It's about me, really. So I

Chris Bolhuis: know. Um, so I'm just [00:05:30] gonna wrap it up by saying I'm doing

Um,

we're, we're kind of hunkering down for a blizzard

so it's, uh, yeah.

Dr. Jesse Reimink: A big one. It seems like a, it seems like a big one. Hitting Michigan bullseye on Hudsonville, Michigan, uh, the map that I saw.

That'll be good. That's, I mean, it's kind of fun to have those once every, every little bit so.

Chris Bolhuis: it is. It'll be nice. I just gotta get my house all like there's some things I have to do yet, because I don't know how long we're gonna be socked in,

Dr. Jesse Reimink: Oh yeah, for sure, Well, Chris, the, the last reason I'm fired up is because this [00:06:00] is a fun episode. This is a really, I really like this kind of stuff. Um, and I know I'm,

Chris Bolhuis: do

Dr. Jesse Reimink: I know you do too. 'cause you know, the,

educator in you is just very excited for this episode, right.

Chris Bolhuis: Why don't you tell everybody what, what happened and how this all came about?

Dr. Jesse Reimink: so a listener of ours, Kat, who is a teacher at the Bronx Little School in the, in Bronx, New York, has a fourth grade class, And they were working on a unit on sort of the natural wonders of the world and the Grand Canyon came up.

And [00:06:30] so, Katt reached out to us and said, Hey, can I, can I send you some class questions? If I have my class put together some questions, can I send 'em to you? so we got a, a list of questions from Kat's fourth grade class from the Bronx Little School about the Grand Canyon. And so we're gonna go through these and this is a really.

Well, Chris, you and I, we just got done, well we just published the Grand Canyon audiobook on the Camp Geo app, so it's a great time for these questions to come up because we've thought a lot about the Grand Canyon recently and put together a lot [00:07:00] of cool stuff and have these answers, you know, readily at forefront of our brain.

So that's the structure here. We're gonna answer those questions, we're gonna go through those and these are really good questions. So really well done. Kat's fourth grade class. Really well done on the questions. These are great, great questions, and some of 'em are quite deep.

Chris Bolhuis: And just to be clear too, when I wrote this out in terms of what we wanna talk about, I kept the questions as they asked them. I, I kind of maybe tweaked the order of a couple of them,

the questions are the same and we're gonna [00:07:30] tackle all of them

Dr. Jesse Reimink: That's right. That's right. and so I think we should just dive in, Chris. I mean, let's work through them. There's kind of

four or five different themes to these and, and also, I must say class well done on writing the questions down. I mean, that was really nicely structured. You had really nice introductions.

I mean, this was a, a, a well formatted

Chris Bolhuis: I

Dr. Jesse Reimink: I would say.

Chris Bolhuis: it was awesome. It was cute.

Dr. Jesse Reimink: it was great.

Chris Bolhuis: And so, Jesse, now listen. Hey, our [00:08:00] audience right now is we're answering questions that came from fourth grade. So you can take your doctor title and put it on that shelf right behind you. Kay. Now we're talking,

Dr. Jesse Reimink: that's right. We're, we're gonna stay outta the weeds.

Chris Bolhuis: good job here.

Okay? Uh.

Dr. Jesse Reimink: we're gonna stay outta the weeds if you want some of the weeds. Not the class necessarily, but you listening. If you want some of the weeds, you can go to our audiobook on our Camp Geo app. We've just published in the last month, we published a Grand Canyon audiobook.

So this is the geological story of the Grand Canyon with great images that we've produced that really drive [00:08:30] home the geological story of the Grand Canyon and what I think Chris is a really beautiful way. So you can head there. That's the first link in your show notes. You can head there, if you're interested in, in more of the weeds.

So, Chris,

Chris Bolhuis: I wanna throw one thing out too. And we didn't really talk about this, but I have an idea too that I would really like to, if you and I can maybe find the time to zoom in with their class a little bit, maybe for like 20, 30 minutes and, and just talk

maybe about education and, and kind of a q and a kind of thing.

I, I don't know. I. didn't really [00:09:00] discuss this, so I know this is like just kind

Dr. Jesse Reimink: Yeah. I.

Chris Bolhuis: in your lap here, but what do you think about

Dr. Jesse Reimink: Oh yeah, totally. You know, Chris, I, I, at least I haven't done the last year or two, but I used to zoom into your class a lot and I think it's a, I don't know what it's like to be on the receiving end of Zooms actually. You know, I had this in my entrepreneurship class we had people come in via Zoom, um, geoscience entrepreneurs to my class and, you know, just discuss and

actually.

It's not that bad. You know, you would kind of think it's, it's not fun to zoom in or, or not fun to not be there in person or to not [00:09:30] interact in person, but it does a pretty decent job, you know? Um,

Chris Bolhuis: Yeah. I mean, we're all in the same time zone. So, Kat, if you're

reach out to us if you're at all interested in this. I think, we'll do our best to try to coordinate something if, you're down for

Dr. Jesse Reimink: Yeah, yeah. And so how about we start, Chris, with Kind of a basic one. I mean, really like you're, look at the Grand Canyon. It's spectacular. It's one of the natural geological wonders of the world. How deep is it? It's a great question. With several different points to it, I think.

Chris Bolhuis: right. So in an, [00:10:00] we're not just gonna answer these questions point blank, we wanna kind of set this up a little

Dr. Jesse Reimink: set the stage.

Chris Bolhuis: when you talk about the depth of the Grand Canyon, I think it's, which is impressive. It's really important to note that the Grand Canyon, the rim of the Canyon is 7,000 to 9,000 feet above sea level.

Because it's so high. That's what allowed the river to cut so deeply through this. So that's something that I don't think a lot of people realize. I mean, even though we're in Arizona, the rim [00:10:30] of the Grand Canyon, either the north side or the south side is significantly high above sea level and it's, it actually gets cold.

I mean, they get snow up there. that's something that I think a lot of people don't realize too. You think of snow in Arizona, but it, it, it. It's a common

Dr. Jesse Reimink: yeah, exactly.

So Chris, that's a really great point, and I think this is why it's a little bit misleading. Or at least the elevation is not obvious because we think of high elevation places, we think of jagged mountains and stuff.

But when you're standing at the rim, you're on the [00:11:00] plateau, which is the rocks are flat all around you. And usually when we see flat land, we're close to sea level. That's not the case here in, in Arizona, in the Grand Canyon. So that's why it's, why you said it's kind of surprising and, and I think that's why is 'cause you look around and everything's kind of flat, um, but you're high.

So it's a plateau is what we call that. Anyway.

Chris Bolhuis: So this high elevation makes the river what you kind of term hungry, Jesse. You say the the Colorado River is a hungry river, so

means. Why is the Colorado so

Dr. Jesse Reimink: This is not a term [00:11:30] that, uh, you and I came up with. It's obviously one we've adapted, but I love the term hungry water. And you think of it as rivers like to, well, they're usually cutting something. They're cutting, they're either cutting down or they're cutting out. we're talking to the Bronx little school students. So you're sitting there, think of, you know, one of the rivers around New York City, you're very close to sea level in New York City and right around there, all the rivers are very close to sea level. So they actually can't cut down anymore.

They can't cut below sea [00:12:00] level. Sea level is a term we call base level, but can't cut down anymore.

Chris Bolhuis: quick. So those, those rivers are slow. They're lazy. They're sluggish, you know, so they're not actively eroding.

Dr. Jesse Reimink: Exactly.

Chris Bolhuis: the opposite.

Dr. Jesse Reimink: not hungry anymore, Chris.

They're not

hungry. They're totally satisfied. They're, they're right near their home, so they're not hungry. Now the Colorado River in the Grand Canyon is seven to 9,000 feet above sea level, or at least it used to be before it cut down. [00:12:30] That's hungry.

There's a long way. Over a mile between that river's where it's flowing and the ocean. So it can cut down a lot because it's at high elevation. And so we think of rivers that are hungry are ones that can cut down. They don't have much sediment. They're not very close to what we call base level or the ocean There's a long ways that they can cut down and that's really why the canyon is so deep here is because the river, the Colorado River is. Hungry in this situation. So that kind of [00:13:00] brings us full circle to answer the question, Chris, how deep is the Grand Canyon?

Chris Bolhuis: Okay, I'll, I'll take it. Okay. So the canyon is anywhere from 4,000 to 6,000 feet

Dr. Jesse Reimink: Oh, amazing.

Chris Bolhuis: in other words, and you just alluded to it, it means it's about a vertical mile. And I, I wanna just say like, I'm looking outside right now, outside my window at my house, and it's kind of

this is. know, in New York it's, it's cloudy season as well. basically on any given day, if you look out and [00:13:30] up at the clouds, they're about a mile high. And so that's what we're talking about. from the rim of the canyon down to where the river is, about the same difference as how high the clouds are.

Does That,

Dr. Jesse Reimink: that, works Chris. It's about four Empire State buildings stacked, bottom to top.

Uh, if we wanna put it in New York terms, um, you know, it, it's a lot. This is tall, this is deep and it's stunning to sort of look at, and I [00:14:00] don't think it's at all obvious that it's a mile deep when you're looking there.

Just 'cause the scale of the canyon is huge.

Chris Bolhuis: and you know, you and I have both been here. I've been down to the very, very bottom of the canyon and where we started at the rim and walked our way all the way down, me and my, my wife and my two kids, and it was awesome. We spent four days down in the bottom of the canyon. so different when you talk about that, you know, what is it like to be a mile apart, right

the bottom of the canyon versus the top.

You have two totally different [00:14:30] climates going on there.

of the canyon in the summertime is scorching hot. I mean, it's, brutal. It can be 120 degrees, but on the rim. It can be a very pleasant 80 degrees on that same day.

it's almost two different worlds.

Dr. Jesse Reimink: and we touched on this in the, in our, our book on the camp Geo app is that, native peoples would use this difference in climate seasonally, right? So in the winter, you'd want to go down into the canyon, you'd stay warmer down there in the summertime, you'd move up to the rim [00:15:00] where it's cooler.

And I think also, Chris, it's important to point out when down in the bottom of the canyon, a mile is a long way to walk back up. You know, like that, that's a serious hiking endeavor to, to go up a vertical mile.

Chris Bolhuis: It absolutely is.

Dr. Jesse Reimink: So, just to to reiterate, you know, the rim of the canyon, seven to 9,000 feet above sea level.

The canyon is over a mile deep from there. So, the Grand Canyon, the river, at the bottom of the Grand Canyon is not yet at sea level. So it's still hungry and it's still cutting.

Chris Bolhuis: Alright, so Jesse, [00:15:30] let's move on to the next question. this one is interesting and this is I think what everybody sees when you go to the Grand Canyon. The question is why are the rocks orange, red, and black?

how are the rocks made? I think I combined the two

How were the rocks made?

Dr. Jesse Reimink: Two different questions. They're, they're intimately related.

Chris Bolhuis: They are though. They're intimately related. So let's go ahead. Let's start off, Jesse, with talking about the rocks that we see. I think we have to start with that,

what are the rocks there? How are they made? Then we'll talk about the colors, because I think that's the [00:16:00] only order that makes sense in in tackling this kind of

Dr. Jesse Reimink: No, I agree with you, Chris. And, and the color is to sort of level set here color's a, there's a bunch of different rocks that have very different formations that have the same color, so. There are a lot of ways to form a black rock, and so black rocks don't mean that it's, you know, formed one way.

There are three types of rocks really, generally in Geology. We have igneous, metamorphic, and sedimentary, and in the Grand Canyon we have all three of them. The [00:16:30] igneous and metamorphic ones, and this is really common on Earth, are. Deeper. The ones right down at the bottom of the canyon, right down at the river level are igneous and metamorphic.

So igneous is a category that means they came from lava or magma. They crystallized from liquid rock. So we had a magma that was molten rock and it cooled and crystallized into form an igneous rock.

Chris Bolhuis: if you look at the word igneous, it's very similar to the word ignite.

and you, you associate ignite with [00:17:00] fire. Right. And igneous rocks then are thought of as born of fire. And so we're

red lava, red magma

Dr. Jesse Reimink: to point out though, we think of lava as like red. When it cools, it usually forms either black or tan or gray. Sometimes it's a little bit reddish, but it forms rocks that are not red. and in the Grand Canyon, the igneous rocks that we have are either, some of them are reddish and some of them are blackish, but they're all down at the bottom of the canyon.

[00:17:30] So the igneous rocks are. Magma that intruded in it kind of shoved its way. You describe it, Chris, as shouldering its way through the rocks and the earth, and then it kind of gets frozen in place. And that's what we look at from the igneous side.

Chris Bolhuis: Alright, Jesse. The metamorphic rocks that we see, they only occur again down in the deepest parts of the

to get up close and personal with these, you have to actually go from the rim down to the bottom at river level to see these metamorphic [00:18:00] rocks. But metamorphic rocks. The word meta means change, and morph means shape or form.

so these are changed rocks. In other words,

a rock that existed and then stuff happened to it. It got subjected to geologic stuff, right? And heat and pressure, which changed the rock. It altered the rock

so you and I often refer to them as metamorphic rocks are [00:18:30] tortured.

they kind

to us, they look like it.

Right? Can you describe that? What does that, when we talk about a tortured rock, what do we mean?

Dr. Jesse Reimink: Yeah, taking a rock and heating it up and squeezing it and putting it under pressure. So when you heat rock up, it can become a little bit like Chris you described as hot plastic. It can kind of flow. It's like putty. If you squeeze it. It'll flow out through your fingers. And that's kind of what happens.

And, and you can imagine like toothpaste, when you [00:19:00] push it out of the tube, if you have that sort of classic striped toothpaste with like blue and white and green stripes in it, if you squeeze that, it'll change that banding, that pattern, that sort of banding pattern will kind of flow in whichever way you want it to or whichever way you squeeze it.

And so these rocks have what's called an internal fabric. We can tell that they have been squished. In order to form that fabric, it has to be squished at high pressure, high temperature. They also, this is super in the weeds, but they have minerals in them. They have little garnets that we can use to [00:19:30] calculate the pressure.

So the,

I, I can't help because it's cool, Chris, this, this stuff, these rocks were metamorphos miles deep in the crust, very deep down in the earth, so very deep down in the earth, and they got kind of buoyed up.

Chris Bolhuis: And the most common metamorphic rock that we see down there, that black colored rock with these kind of whiter and different colored toothpaste veins running through it. It's called a schist

That's S-C-H-I-S-T sch.

Dr. Jesse Reimink: That's right. and Chris, let me just, [00:20:00] the, the colors, so we talked about the igneous rocks can be red or black depending on if it's a basalt, the black one, or if it's a Granite, the red reddish kind of one. the schist is usually pretty dark colored. It can be dark colored with little white streaks in it.

It'll be kind of banded, a little bit banded. that's what you think of. But generally dark colored. Now we're gonna move into the sediment layers because above that we have this. Huge package of sedimentary rocks. Very flat lying. The ones when you look at the Grand Canyon, it looks like horizontal stripes.

[00:20:30] These are all sedimentary rocks, which is the third category of rocks and sediments are formed by water. Water depositing stuff out of it. There's kind of a couple different categories, but generally these things are, are being deposited by water in an ocean. So an ocean is dumping sediment out and that stuff's being compacted and then forming rock from it.

And these have massive color variation. The sediments are just,

I don't particularly love sediments to study, but they make the Grand Canyon spectacular. The [00:21:00] sedimentary rocks here.

Chris Bolhuis: Jesse, you can't say that anymore. Come on With all the stuff that we've done with the Grand Canyon, you're not allowed to say that you don't love sedimentary rocks more, right?

Dr. Jesse Reimink: Okay. Fair enough. Fair enough.

Chris Bolhuis: I'm calling you out on it. So look. Sediment, they look different. Sedimentary rocks look different from the other two that we've already described.

I mean, I always say that it's kind of simple and kind of dumb, but you know what? If it looks like dirt, tastes like dirt, it's because it's

sedimentary rocks are made of this loose sediment that got [00:21:30] compacted together.

Dr. Jesse Reimink: that's a great way to put it, Chris, because these rocks, They're not as well put together as the ignition metamorphic ones. They're easy to break apart. and there are some that are harder to break apart, some that are really easy to break apart. So that's why we get the cliffs and then we get slopes and they kind of occur in patterns across the canyon.

But these have a ton of color variation and In general, the color variation comes from the amount of iron in the rock. And the way to think about this is rusting. when something rust, we think of rust turning red. If you [00:22:00] have a, a steel plate and it gets rusty or a steel utensil, it gets rusty.

It turns kind of a dark reddish, right? The same thing will happen in rock and it doesn't take a lot of iron in the rock to form this rusty color to kind of have this iron staining to it. and it.

Chris Bolhuis: It's shocking. I mean, j not very much iron at all, as, just as little as 3%

in the rock can make the whole rock be stained a different color,

Dr. Jesse Reimink: right. And so the white rocks typically [00:22:30] have no iron in them. some of the ones at the top of the canyon typically have no iron in them. the sort of the greenish to grayish. Rocks will have iron in it, but it will not be rusted. It's kind of unrested iron, if you think of it that way.

That's kind of the, the green rocks there and then orange is a little bit rusted and red is very rusted. You can kind of think of it or d, different types of rusting, different types of rusting reactions, I guess. How about that?

Chris Bolhuis: proud of you right now. I am proud of you, Jesse.

you really took your [00:23:00] geochemistry funny little brain over there, and you, you kept it. I love it real quick, Jesse. Something that. an analogy or something that they might be able to tie into in terms of iron stain in a rock, right? walking down the sidewalk, we often see these brown stains. In a sidewalk, they resemble the, kind of the way a comet looks, if you will. You know, you got the, the head of the comet and this like

streaks away. We see these all [00:23:30] over the place in roads and sidewalks and, that's a perfect example of iron staining a rock, because

those brown streaks that we see on a sidewalk that's from an iron bearing mineral. That is a part of the material that makes up the, concrete or the

So that little tiny bit can bleed into, a much larger part of the sidewalk.

really what happens with this kind of iron [00:24:00] staining that we see all over the place. And that makes the Grand Canyon so absolutely

Dr. Jesse Reimink: So beautiful. I mean, these sort of pastel reds and oranges and whites and grays and greens, uh, so beautiful. So, that's a great analogy, Chris. I, I like that one. And it's kind of really drives it home that it's mostly about iron. That's going on in, in the, that's giving the color to these rocks.

So Chris, the next question here is, why is the Grand Canyon so steep? And there's kind of [00:24:30] two parts to this. Let me take the first one, Chris, and then you, maybe you can take the second one. the first one is. Fairly simple. We've talked about it before, the river's hungry. And as we said before, a hungry river is one that's like way above sea level, so it wants to cut down.

It's really wanting to cut down. And so if a river's hungry, it cuts down first before it starts cutting, like outside to side. So it cuts down first, which kind of makes steep sides if you kind of envision. I guess the way to think about this is you, if you cut down, the only way the [00:25:00] sides are gonna move is if they kind of collapse in on themselves and all those sediments in the Grand Canyon, they form cliffs. So we end up having a really steep sided canyon when we have a hungry river, because the river's cutting straight down. Think of a mountain valley stream, it cuts straight down, which means you have really steep sides to it.

Chris Bolhuis: There's a common saying with the Grand Canyon the saying goes like this, old rocks Young Canyon.

you have a hungry river hasn't been down cutting [00:25:30] for very long. Now, geologically it hasn't been very long from a human standpoint. It's been going on for a long time. But we'll touch on that as we wrap this episode up. But canyon is young, and you were to come back to the Grand Canyon in a million years. It would look really different than it does today. It would be much, much wider. And I think actually Jesse, probably less impressive. I think one of the things that makes the Canyon so beautiful is the [00:26:00] fact that it is very steep from this aggressive,

actively downcutting Hungry River, right? But. Now that the river is, getting closer to sea level, it's beginning to change its dynamics a bit. And what that means is now it's also going side to side more than it has in geologic past. And so as the river goes side to side, it's undercutting other rocks.

you have then, what this creates is what's called rockfall,[00:26:30]

occurrence.

Dr. Jesse Reimink: just describe it in an analogy here. Like, you go to the beach and you know, you're making a sand castle, let's say, and the water is kind of coming up you build it right on the edge and as the tide moves in and out, the water starts coming up and kind of hitting your sand castle a little bit.

but it's. Calm day, so the waves aren't crashing into it. They're just kinda lapping the edge of your sand castle. The water is gonna hit the base of your sand castle, and it's gonna start to move some of the sand from the bottom, the sort of bottom edge of the wall of your sand castle, [00:27:00] which means it's gonna.

Erode right there. And then you get to a point where the wall of your sandcastle, the top, you have like some turret, let's say you've got like a, a nice turret up top. It's gonna be unsupported 'cause the bottom has been eroded out from underneath of it and it's gonna collapse down. And then the water can start to erode that collapsed material and start to eat away at that collapsed material.

is that a good analogy for the process that we're kind of describing?

Chris Bolhuis: that was worthy of an interruption, Jesse.

Dr. Jesse Reimink: Okay. Thank you.

Chris Bolhuis: nicely done.

Dr. Jesse Reimink: I like [00:27:30] that.

That was a good way to phrase it, Chris. Worthy of an interruption. You have to have something very important to say to interrupt Chris

Bois.

Chris Bolhuis: you better? better. Um, so when that collapse happens in the Grand Canyon, called a rockfall. And these are spectacular things to witness and to to hear because it's just this loud, thunderous crashing, yet awesome event if you're fortunate enough to, to, you know, to witness one of these [00:28:00] things, but. and when that happens, then it results in the canyon becoming just a little bit wider,

over geologic time, it's gonna get wider and wider and wider and a little bit deeper. So it's widening now more than it's deepening,

makes sense. You

Dr. Jesse Reimink: river's getting less and less hungry, less and less hungry, and so it's cutting out instead of cutting down. So it starts, as it gets less and less hungry, it starts to cut out a little bit more. So

Chris Bolhuis: now, Jesse, you can stand on the South Rim of the Grand Canyon and you can pretty [00:28:30] easily see across the canyon, to the north rim, to

the plateau. come back in a million years and you probably will not be able to see across from one rim to another.

it'll widen that much.

Dr. Jesse Reimink: It is gonna widen a lot,

which brings us very nicely. I think. Chris, we're starting to talk about time to really the last question here, which is how old is each layer of the Grand Canyon? And I think I want to. As a way in, as a way to describe this, Chris, you have a really nice analogy or [00:29:00] nice visual for this.

But before we get to that, I want to come back to our question about the rock colors and talk about the different packages of rocks that we have. 'cause we talked about how the igneous and metamorphic rocks, the really hard rocks are down at the bottom of the canyon really far down there near the river level.

So that's kinda one package we're gonna talk about, the igneous and metamorphic rocks, what we call the quote unquote. Basement, way down at the river level, there's another package of rocks, of sediments, and these are tilted sediments They're sitting right on top of the igneous and [00:29:30] metamorphic rocks, but they're below the main sequence of rocks, so they're kind of in the middle there.

They're set of sandwiched in the middle. And then the third package of flat lying sedimentary rocks is what you see from the rim, the, the sort of rim of the canyon. You can kind of see all the way down to, what's called the Tonto platform, this sort of big platform that you can easily see that kind of hides the river when you're looking down at.

So most of what you see in the Grand Canyon is this last package of rocks, but there's three in there and you can see [00:30:00] all three of them just depending on where you're standing.

Chris Bolhuis: we can't talk about the ages, or at least we, we could, but it wouldn't be really appropriate here to talk about the age of each rock layer because

a hundred different well-known rock layers that

up the Grand

divided it into three categories instead

Dr. Jesse Reimink: And let me interrupt real quick, Chris, there, because this, uh, this is an important point, this is really complicated. We are oversimplifying this and [00:30:30] there's a lot of really interesting unanswered questions about the Grand Canyon and about these rocks. It's, You could spend a long time studying the Grand Canyon. There's a lot of detail. The Grand Canyon Geological story that we're not talking about. So I, I think that's inspiring. Like, I think that's inspiring, especially for students to be like, whoa, there's more to learn here. And I just wanted to double click on that and say there's a lot more to learn here.

Chris Bolhuis: So In order to do this though, Jesse, I think we need to talk about age a little bit.

it's always fun. I don't care where you are. If [00:31:00] you're listening to this, where you are in your geologic background, you have a really deep background or whether you have almost no background to wrap your mind around geologic time.

is a fun exercise, I think, for everybody because it's,

impossible to, yeah, it is. It's nearly impossible to comprehend. So here are some analogies. Let's, should we do that?

Dr. Jesse Reimink: Yeah, I, Chris, I love, I love this analogy. You've got, so, yes. Take it away.

Chris Bolhuis: Okay. geologically the earth is [00:31:30] 4.54 billion years old, which is a number that is very difficult to comprehend. So let's first talk about a million, because to me, I have a hard time with a million and we

around it all the time in Geology,

Hey, come back to the Grand Canyon in a million years and it's gonna look really different than it

Dr. Jesse Reimink: Oh, casual. Yeah, casual.

Chris Bolhuis: Yeah.

Dr. Jesse Reimink: What does that mean?

Chris Bolhuis: I'm chucking that around like no big deal. Right. Well, so let's, let's try to like do this a little. I have just one analogy. [00:32:00] I, I a million, if you were to count to a million. Counting once per second with no breaks at all, no naps. You didn't go to sleep or anything like that. It would take you 11 days and 14 hours to count to a million. that's, that's

Dr. Jesse Reimink: It's a long time.

Chris Bolhuis: But counting to a billion would take you a same way.

No breaks one every single second, no naps. It would take you 32 [00:32:30] years. To count to a billion.

Dr. Jesse Reimink: Just amazing.

Chris Bolhuis: no human. Jesse, not even you. you like to think of yourself as superhuman sometimes. Not even. You could count. To 4.54 billion years, you couldn't do this because you're not gonna live to be 147 years old, which is how long it would take you 147 to count to 4.54

Dr. Jesse Reimink: Amazing. I, Chris, I just wanna, I [00:33:00] just wanna reiterate that, restate that because it, it, it really nicely shows the difference between a million.

A billion.

Chris Bolhuis: you're superhuman? Is that what you're restating?

Dr. Jesse Reimink: Yeah. Yes. That part. Exactly. Uh, so just so everybody knows, uh, no, counting to a million would take 11 days and 14 hours. that's okay.

We can conceive of that. A couple weeks counting to a billion would take you 32 years. I think that really highlights the difference between a million and a billion very, very nicely. I like that one a lot. and Chris,

say. This is a really hard thing for [00:33:30] everybody to comprehend. Like even practiced seasoned geologists like ourselves,

we throw these words around a lot, but actually comprehending it is, is still very hard.

At least for me personally.

Chris Bolhuis: are so many cool things that you can do with

You know, like, alright, you can string how many paperclips around

Dr. Jesse Reimink: Yeah. right.

Chris Bolhuis: paperclips, how many times would they wrap around the earth? And, you know, you can

There are so many cool exercises that you [00:34:00] can do in education to, to mimic what geologic time looks like and how vast it is.

like you said, it. I don't care where you are in your geologic, background doing this is always fun and I think a valuable exercise.

Dr. Jesse Reimink: Absolutely. Okay, so how old then Chris? We've kind of thought about deep time. what the, these big numbers mean. let's frame it. How old each layer is. Let's go back to the three rock layers again. The, the old stuff at the bottom. Young stuff on top. frame this for us? How do [00:34:30] we think about this?

Chris Bolhuis: so the oldest suite of rocks, what you termed the basement rocks, and I just, I, it's a term that we use in Geology all the time, and I love it

it just makes sense. These are the bottom bedrock hard rock stuff, right? These basement rocks in Grand Canyon are 1.84 to 1.66 billion years old

again, so Jesse. Should we do the our our year

Dr. Jesse Reimink: Yeah, I like this. Chris, let me [00:35:00] just let, so you said 1.84 to 1.66, and the Earth is 4.54 billion years old, 4.56 billion years old. If we think of Earth Time as a year, so January one, earth started. December 31 is you know, today

Chris Bolhuis: and 59 seconds.

Dr. Jesse Reimink: is today, if we think of, the Earth time as one single year, where does 1.84 and 1.66 billion fall in a calendar year of [00:35:30] earth history?

Chris Bolhuis: Yeah, that would be from August 6th to August 21.

about it that

So that means that there isn't a record January, February, March, all the way into August. There's no record of rocks in the Grand Canyon for that whole part of the year.

they're not there.

Dr. Jesse Reimink: And this is a good little lesson to pay attention to here. There, there's a lot of missing time. There's a lot of missing time in the Grand Canyon. There's [00:36:00] a lot of rocks. There's a lot of beautiful record preserved, but there's a lot missing as well. So that's the oldest suite, right?

August 6th, August 21. That's 1.8 to 1.6 billion years ago. This. Layer of tilted rocks. The second series, these are sedimentary rocks, what's called the Grand Canyon Supergroup. These are 1.1 billion years, 1.2 billion years, and then it also, there's some that are 800 million years old, so right around, we're kind of closer to a billion years in this, on our calendar year is [00:36:30] end of September.

To early October, and then end of October to early November. So we're kind of, we're in the fall season here, you know, September 22 to October four, and then again October 28 to November two.

okay, so Chris, that's layer one, two. What about the big stuff? I mean, the stuff that dominates the really spectacular rocks at the Grand Canyon. Where are those on our geologic clock?

Chris Bolhuis: Yeah, they're, it's called the Paleozoic Strata. It's what everybody sees when you go to the Grand Canyon. And, [00:37:00] you know, geologically the numbers on them are, a little over 500 million years old to 270 million years old.

in a calendar year, that's November 19 to like December nine.

Dr. Jesse Reimink: so this is relatively recently compared to you know, the start of earth, it's crazy.

Chris Bolhuis: it's not even a month, Jesse. The, this vast volume of rocks in a, year timeline doesn't really like a lot,

it's,

it's shocking.

Dr. Jesse Reimink: Crazy, crazy. So those are few hundred million [00:37:30] years old and there are some rocks. They're relatively minor and you're not gonna see them unless you head to the western part of the Grand Canyon. but you see them on the drive to the Grand Canyon, or if you're kind of in that region, there are young volcanic rocks that are a few hundred thousand years old.

And so these would be, I don't know the calculation. These are like end of December type rocks, like, you know, the last day of December kind of rocks here.

Chris Bolhuis: Eve? Yes.

Dr. Jesse Reimink: Exactly right. Um, so these are pretty young in geologic terms, a couple hundred [00:38:00] thousand years old. but you're not gonna see a lot of those. The bulk of the Grand Canyon is that August 6th to August 21, then end of September, basically to early November. And then another, series from November 19 to December nine. That's kind of the big bulk of the rocks that you see if you're standing on the rim.

Chris Bolhuis: So, Jesse, before we wrap this up, and we're getting a little bit long in the tooth here, but there was one question that they didn't ask that we can just touch on real quick,

how exactly did the Grand Canyon get cut?

Because this is a, [00:38:30] we devoted almost an entire chapter to this in, in our audio visual book of the Grand

the reason why this is a big deal is, is what Jesse, and this, this bothers me and I get on you about it sometimes, but

Dr. Jesse Reimink: Yeah, it, it bothers you and it, it excites me and I think it, it should excite students, I think, is that we don't know the answer to that. Like, really? Okay, the river's hungry, but how did it get so hungry? How did it do the cutting? Like we don't actually understand that as a scientific community. So there's more yet to [00:39:00] discover, which I think should be inspiring to.

People who are in classes are asking really good questions. So, this, this class, fourth grade class at Bronx Little School signed their letter, the Epic Earthlings. And so the Epic Earthlings great questions, really well written letter to us. And there's more to learn, so keep asking questions 'cause there's

Chris Bolhuis: Maybe one of them will figure out

got cut.

your story right there.

Dr. Jesse Reimink: Exactly. It, it, [00:39:30] I, I think it should be thought of as inspiring that there's more to learn about the Grand Canyon, which we know a lot about already. So, I don't know, Chris, uh, that was fun. That was good. And if, you know, we stayed outta the weeds, I think we did a pretty good job. If you want more of the weeds, you can go to our Camp Geo app and you can get access to our Grand Canyon audiobook, which is the full geologic story of the Grand Canyon, and in like 10 chapters with all the images you need. If you want to send us an email, if you have more questions on this, please send us an email, planet Geo [00:40:00] cast@gmail.com.

You can hit us up on all the social media. We're at Planet Geo Cast, and you can head to our website, planet your cast.com.

Chris Bolhuis: Cheers.

Dr. Jesse Reimink: Thanks for the questions. Peace.

Jesse Reimink

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