Rocks Rock: Geology 101 and How Our World is Built

In this episode of Wildly Curious (formerly For the Love of Nature), Katy Reiss and Laura Fawks Lapole take listeners on a deep dive into the fascinating world of geology. From the origins of Earth's rocks during the chaotic Hadeon era to the formation of towering mountains like the Appalachians, they break down complex geological concepts with humor and clarity. Learn how plate tectonics shaped our planet, what makes rocks like granite and pumice so unique, and how geology impacts every aspect of life on Earth. Whether you're a geology novice or a rock enthusiast, this episode will leave you in awe of Earth's ancient foundations.

Transcript

Hello, and welcome to For the Love of Nature, a podcast where we tell you everything you need to know about nature and probably more than you wanted to know. I'm Laura.
And I'm Katy, and today we're talking about rocks and, well, how they rock.
Yeah.
So, geology is what we're gonna be talking about, and it's a field of study that really is foundational to understanding how our world operates and exists today. And normally, when you think of geology, it's not as interesting sounding, but I promise Laura and I will make it fun.
Well, I think it totally depends on like who's telling you about it for sure.
Yeah, oh, definitely.
And how much of a nerd you are, because I've always been into geology. I actually went on a geological tour of my county with my mom before.
That's intense.
Like, I'm into geology.
I, okay, for me, it's very similar to genetics. I'm very interested in it, but only to an extent. Like, tell me the cool stuff.
Don't give me an over, like, just don't give too much. Then it just gets boring. But anyway, so, I mean, it is Laura and I, so we're gonna make it as interesting as possible.
But if we think about it, you know, because of how geology happened and how it is happening, it really does play a vital role in everything and everything else nature-wise that we talk about. Because without geology, we really wouldn't have any other nature and how geology formed and everything.
Right, we wouldn't literally have Earth.
Yeah, so we're probably gonna be doing multiple geology episodes moving forward, I can imagine. But for-
Totally, at some point, I wanna talk about gems.
Yeah, that would be a cool one. All right, before we get into rocking about rocks, do we wanna do nature news? I have a nature news.
Yeah.
Oh, first though, I wanna say, guys, you need to download, if you haven't already, it's By News Fusion, which is a company that they just put out these various apps that fuse the news. And there's a science news app, By News Fusion, and it is amazing. Download it right now.
But you can go in there, and you can go by topic. So if you wanna know space stuff, I'm subscribed to space, conservation, nature. I forget, just a ton of them.
I literally went through tons of stuff, and just started clicking on everything. And it gives you all one easy app, and then you can just scroll through. So I am never gonna have problem finding nature news again, because it's literally in one.
And I get the updates of the cool topics I really wanna know about. It pings to my phone, so that's really cool. And so this one I actually found on the app, and I was like, using it.
So researchers have recently discovered that octopus ancestors lived before the era of dinosaurs.
Of course they did.
Exactly. I mean, they're intelligent enough. So scientists have found the oldest known ancestor of octopuses, an approximately 330 million year old fossil unearthed in Montana.
Dang.
Yeah.
Which, I mean, I guess we'll kind of talk about in our geology episode, why was Montana in the ocean?
Yeah, right, because it was, so this one that they found was a 4.7 inch fossil that had 10 limbs. Of course, an octopus today has eight, so I guess they were just like, you know what, 10 seems a bit excessive, let's just lose a few, lose a couple. Eight's a good number.
And on those limbs, there were two rows of suckers and they think it lived in shallow tropical ocean bay. And so the scientists were talking about, yes, it is very rare to find tissue, because again, it's an invertebrate.
Well, right, and when you listen to our fossil episode, you know how hard it is actually to form a fossil, especially with soft tissue stuff.
Yeah, nearly impossible. So for them-
That has to be absolutely the perfect conditions.
The perfect conditions. So it's for them to find an octopus, which is all soft tissue. That's pretty amazing.
So anyway, so yeah, so that one, let me see, what was, that was physics.org. Or what is it? Yeah, physics.org, I think.
Anyway, but yeah, News Fusion app, download it. It's amazing. It is gonna change your life.
It has certainly changed mine, but kind of informational-wise. So, all righty. Are you ready to dig into this Jology episode?
I am ready to rock and roll.
All right. I will be saying as many rock puns as possible in this episode. So, that's how I'm gonna keep myself entertained.
It won't be hard.
But, all right, so what is geology? And that's what we really wanted to backtrack here for one second. Laura and I are gonna start doing some episodes because a lot of our audience is nature novices.
We are gonna start grabbing different sections of science and kind of breaking them down. And so, this is one of them. So, we're gonna start with some Geology 101 and then just dig a little deeper into each area, just to go, like just to scratch the surface and then kind of start those cracks down through it so you guys can learn a little bit more.
All right. So.
I feel like literally everything we're going to say is a rock pun. Like you don't even mean it.
No.
Scratch the surface and then cracks.
Oh no, I didn't mean it.
Okay, okay, good.
Yeah. Cause I even say like that I too have been at fault for thinking geology is just.
All right, all right.
It's so, it's so good.
Tell the people what geology means.
So, well, I have been at fault for thinking geology is just three basic types of rocks, and that's pretty much it. But most of what I love about nature and the natural world really does have an element of geology to it. Anyway, I'm just going to keep doing rock puns.
Not as many though.
Please do.
I heavily rock pun the beginning of this because I thought it was going to be boring, that I found some interesting stuff. So anyway, so what I love about nature can be traced back to geology, like I said earlier. So we're going to break it down.
All the stuff you learned way too long ago in elementary school, but probably have a greater appreciation for it now. At least I think I do.
I definitely remember specifically learning about the rock types in sixth grade because I cartooned them as we learned them.
Pause, you cartooned them, like drew them, or you like gave them life and animated them?
Oh no, not animated, just like made them into-
I was like, do these have plot lines and everything?
It was like a rock band. Of course, they were all dressed up as their different types, but like, yeah, it just helped me remember and I loved doing it. I was really into cartooning in sixth grade.
And rocks, apparently. All right, so geologists classify rocks of the Earth's crust into one of three categories, igneous, metamorphic, or sedimentary, based on how the rock was created. And Laura is gonna-
I'm just gonna say dig deeper into those three.
I'm gonna crack that subject in.
Yeah, right? So, but even though there has to be certain conditions for each of these rocks to form, these conditions change their original minerals of the rock into new minerals. Popular metamorphic rocks are pylite and marble.
I'm trying.
I'm gonna help you guys out when in my section.
Okay, good. Sedimentary rocks. Let's see here.
Sorry, I don't want to give too much away of what Laura was saying. But anyway, okay, let me just skip through some of this because I don't want to give away too much of what Laura said. So then the sedimentary rocks too.
Let's see here. All right, so what I totally forgot about. So you have your sedimentary rocks, your igneous rocks, metamorphic rocks that Laura's gonna tell you more about.
But there's a thing called the rock cycle, and each of those rocks can turn into each other. So like sedimentary rock is exactly what it sounds like. It's made up of sediments.
And by melting and cooling, it can change into igneous rock. By weathering, an igneous rock being broken down can be a sedimentary rock, of course. And by the same way, a sedimentary rock can increase the temperature and pressure and turn into a metamorphic rock and so on and so forth.
All right, which again, I feel like I forgot that they can change to one another.
I definitely did forget that one. It's pretty cool that they're all...
Like it makes sense, but...
Right, because they're all made up of their...
Each other.
Same parts, but the fact that, yeah...
You're not always the same Rocky were.
And if you guys look up like the actual picture of the cycle, it's pretty cool because it's not like the recycle symbol. It's not one leads into another. It's like all diverted around.
Yeah, depending on what happens. And again, I think it'll make a little bit more sense whenever Laura tells you the breakdown of them. But anyway, so I totally forgot.
And so that is very important. Thinking of it that way is knowing that once you're one type of rock, it can change into another type of rock. I feel like that's very important to remember just based upon things like weathering and stuff that we're going to get into later because things change, especially over time.
All right, so something else that people often forget about is plate tectonics. Basically, we're all just chilling on floating rocks, slowly floating around the earth. I mean, not exactly, but basically.
So, again, to get into the 9th grade accelerated science program, over the summer, you had to write a paper to get in, and I had to write a paper on tectonic plates entering into 9th grade. What a summer project! I was not thrilled.
No, right? That's a horrible summer project. But so, I mean, Laura could probably tell you too, then, in her 9th grade form.
So plate tectonics make up the outermost layer of the earth. And that's what we'll mostly be focusing on for these episodes, because that is, for the most part, what everyone can see. Kind of.
Alright, so what are plate tectonics?
That's so big! We'll pretty much focus on that, because it's mostly what you can see.
Kind of. Depends on where you are.
It's earth. It's the land.
Yeah, and the stuff under it. So a plate tectonic, think of a plate floating on a rock island that butts.
I kind of think of icebergs.
Yeah, and each of those icebergs, or plates, butt up against one another. And you can't see this, listeners, but I wrote out butts, B-U-T-T-E-S, because it's a type of rock formation. So when these plates collide, they give us reactions like forming mountains or giving us earthquakes.
So beautiful landscapes or death, one or the other. So, and there are several... It's like, you know what?
We're gonna collide, and it's either gonna be beautiful or deadly. Like, there's no in between. Alright, so there are several types of plates in the world, but to keep it simple, there are seven major plates.
We here in the US live on the North American Plate. Again, these plates give us the land masses we see today. But those plates are always moving just really freaking slowly, which is everything in geology, just really slow.
Well, right, it's on a different time scale.
A whole other different time scale.
We talked about how trees are on a different time scale.
Trees, no, this is a whole other. This is way slower. So most of us with the plate tectonics have heard of the term or place of Pangea, or how all the earth's current continents used to be one giant landmass.
But this didn't occur, Pangea, until the early Jurassic period.
Yeah, yeah, which I actually mentioned later too.
Perfect. So there were eight supercontinents before Pangea, though. And I think we just hear about Pangea more because it's associated with dinosaurs and who doesn't like dinosaurs.
Right. Probably more fossil evidence too.
Exactly.
Because I know that there were different plates for their back, and I'm sure they've constantly changed.
So the ones that were before Pangea were Valbarra.
Whoa.
Yeah, it's V-A-A-L-B-A-R-A. But the AA, Valbarra.
Val-barra. It sounds like some Viking word.
Ur-can-or-land, Columbia, Rodinia, Pan-ta-Pan-o-sha, or Russia, and Euro-America. Like, all right. So Valbarra is the first supercontinent, which existed about 3.6 billion years ago.
That's a long time.
But what was before Valbarra, you ask? Because I did. This existed in the Hadeon era, and it was just really freaking unstable back then.
So before we had land, it was just chaos because we didn't always have land. And again, I feel like people forget that.
Yeah, like that's something you never think about. I always think, like, if I go back in time to the beginning of the world, it's the ocean.
Yeah.
But of course, that can't be the way it was. Something had to be before that. All this crap flying around, solidifying a little bit, turning into, like...
Yeah, I just imagine it's just a flaming ball of magma.
Pretty much. So in the Hadeon era, throughout that part, there were impacts from, like, comets and ash stories, which released enormous amounts of heat that likely prevented most of the rock from solidifying at the surface.
Gotcha.
As such, the name of the interval is a reference to Hades, the Greek translation of the Hebrew word for hell. So back then, Earth's surface was incredibly unstable, like I said. The heat in the mantle brought molten rock to the surface and caused coaling rock to descend into magmatic seas, and it just kept going and going.
So it's making... it's that cycle again.
It's the cycle, but it's just, like, hot, and everything's...
The civilified version.
Yeah, and everything's just melted.
Hot cycle.
Yeah, just a hot cycle. So heavier elements such as iron descended to become the core, whereas lighter elements such as silicon rose and became incorporated into the growing crust. So it either sinks or it floats, for the most part.
Although no one knows when the first outer crust of the planet forms, some scientists believe that the existence of a few grains of circon dated to about 4.4 billion years ago confirmed the presence of stable continents in liquid water and the surface temperatures were probably less than 212 degrees Fahrenheit at that point.
That is crazy that we found maybe the first ever rock.
Yeah, and it's just like a tiny fragment of it.
Yeah, well, it makes sense. Holy cannoli, so long ago.
Yeah, so since I've seen some stuff, since Hadean times, nearly all of this original crust has subducted from the movements of tectonic plates and thus few rocks and minerals remain where it's visible, where we can get to them.
What is subduction for our listeners?
It's sideways and downward. I knew there was something more than just downward, but it's sideways and downward. So yeah, it's just moving.
So those early surfaces, because of the plate tectonics, pretty much they just started going under one another.
And then they turn into magma.
So it wasn't until after Haitian Eon that rocks started forming and life and rocks existed. Before that, everything was just too hot, except lava.
So, which is an interesting place, that those are the first three places that we found some stuff, which I found some mind-blowing facts in this one.
Oh, I can only imagine.
So the ages of the rocks are generally, in these three locations, Canada, Australia, Africa, are between 2.5 and 3.8 billion years old. And so this is what we can actually see. These are rocks that we can get to.
The approximate ages have a margin of error of millions of years, which is also insane, that it's like, oh yeah, it's just millions of years. Yeah, it's fine. So in 1999, the oldest known rock on Earth was dated to be 4.03...
I think it was... million? Yeah, million, and is part of the Acosta...
No wait, it would have to be billion.
It would have to be billion.
Yeah, it is billion.
Okay, okay. There's just like a word missing. Okay, the Acosta of the slave Crayton in northwestern Canada, which oddly enough, a lot of early rock formations were found in Canada.
It just so happens that the Canadian Shield is one of the oldest found on Earth. Yeah, and so you know like the northern part, and I'm talking like the northern part of Canada, like with all the islands. Like there's a reason it has all those islands there.
That's the oldest part. Oh. Because it didn't always look that way.
It used to be filled with huge, very active volcanoes. The change of this area to what we know it as today was caused by the erosion of glaciers, which I knew the glacier part, but not everything else.
Not the volcano part.
No. It's so old, in fact, that while the actual age of this area is highly debated, many believe that the oldest rock formations in the world are found here dating to be, yeah, 3.8 to 4.28 billion years old, which means this could be some of the first rock formations before any supercontinents actually existed. So it's like the OG of rocks.
So the formation and area of these, like, possibly original rocks is the, gosh, the Nauvaquig Greenstone Belt on the coast of the Hudson Bay in northern Quebec, again, it's like right as you start to enter into all those islands, is where this is found. So again, while scientists still debate over some things like the age of rocks, we do know that rock formations, plate tectonics, and geology in general, they are the foundation of understanding how our world operates and exists. So hopefully that gives you an insanely brief overview of at least some of the more interesting side of the history of geology.
And 101.
Yeah, yeah, yeah. We'll keep going with the timeline of the whole thing. I've got a little bit of extra, so Katy was just talking about the beginning of all rocks.
Which was hell.
Right, literally. From there, we get into some other eons, and the geological timeline, you can look it up. It is broken into a million different pieces.
It really is, yeah.
There's eons, and then eras, and then all sorts of things. But after the Hadeon, it was the Archeon, which was, again, billions of years ago. And that comes from the Greek word of beginning, because this is the beginning of the rock record.
And everything.
Yeah, right. This is when things were being able to be created. So rocks started forming in the Archeon era.
Or era, eon. And then from then, it was the Proterozoic eon. Proterozoic is when things like oxygen started happening.
So the rocks allowed there to be room for things to grow.
And see, that's what I like. Like, I like learning about, again, it's still the biology side of all this, that I always go back, but that's what I like. I love learning about the different eons and everything.
So this one goes from 2.5 billion to 541 million years ago. So it's a pretty big, more recent eon, in the grand scheme of things. And during it, there was what was known as the Great Oxygenation Event, which sounds pretty cool.
But basically, so this is when plants started producing photosynthesis. But what happened was, which I had no idea, that the minerals that existed at that time sucked up the oxygen and didn't let it go out into the atmosphere.
This is mine.
Yeah, it was sucked up in particular iron, and so this is huge bands of iron were formed and held on to that oxygen. And then finally, they were so saturated that it bubbled up into the ocean and then bubbled up from the ocean into the air and allowed the atmosphere to kind of be created the way it is. This is also the formation of when these supercontinents started really happening that Katy was talking about.
So nobody really knows exactly how many. But the best known one, at least during the Proterozoic Eon, is Rodinia. And basically, we know how it was formed because we can put it back together like a puzzle by looking at mountain chains.
Because when these, like Katy said, when these big plates smash into each other, think about two cars crashing and their hoods crumple. It's the same thing. So they crash, they crumple, and they form mountains.
And they form mountains in different ways, too. And that's what, like, the subduction that we were talking about. Did you go into that a little bit more at all?
Because, like, okay, because I don't remember all the names, but there's different ways that these are formed, too. So it's either, like, the plates both go up, one goes down, one goes up, they, like, subduction where one goes sideways, one goes down. So, and you can see that, like, the different types of collisions, apparently, and the different formations.
And, like, how the rocks are angled and, like, things like that. It's pretty cool. It's almost like art.
Yeah. So then, and then this is where I've never even heard of these before, I don't think. Have you ever heard of stromatolites?
I don't think so.
You'd really like this, okay. Or you will really like this, I should say. Okay, so this is the first evidence of life on Earth.
So it's basically a fossil, but it looks just like a rock. And if you look it up, there's a ton of them in Australia. They're also in different parts of the world.
So what happens is at the time, this rock is forming, the oxygen is forming, and then this allows water to form. So in this water, cyanobacteria, which is kind of like, we talked about it in our symbiosis episode when we talked about lichen. It's kind of like a plant bacteria, kind of.
So they grow. And then because of the stuff they're secreting, that causes calcium carbonate to form, which is like a hard substance. Think of calcium.
And then that falls down on top of them. And then other sediment, like mud and stuff, falls on top of them. And it's sticky.
The cyanobacteria are creating this sticky substance. So it gets sticky, and then it hardens, and then it goes up another layer, and then it hardens, and it goes up another. So it's kind of like the concept of coral, but it doesn't look like coral, because it's really just layer on layer on layer on layer on layer.
And they form these really weird, almost look like rock mushrooms.
Yeah, they do.
And so that is the first evidence of life on Earth. So we can kind of know like, boom, this is where it all started.
Which again, you said Australia. I mean, that's...
You're right, that totally tracks, because I didn't know that.
Yeah, Australia, Canada, and Africa.
So then finally, we go into what we're in now, which again, I thought it was kind of weird that there aren't that many eons. There are just tons of eras. So we are starting 541 million years ago.
To the present is the Phenerozoic eon, which means visible life. And that is when Pangea was formed. So that supercontinent Pangea that we've all heard about at least at some point, formed up by a whole bunch of different plates, but in one giant mass.
During this time is when the Appalachian Mountains were created, which is...
Shout out to the Appalachian Mountains.
So the Appalachians formed when these things rubbed together. And the whole mountain thing, I don't go into a ton. I feel like we could do a whole other episode on just mountain.
Because I feel like, okay, so I feel like the comparison, like you said earlier, it looks like artwork. I really feel like it's, you can tell, it's almost like how you can read a river. You can read mountains versus about how they look.
So knowing about the history and how they're forming, you can kind of read the mountains to tell a story behind it, just like you would read a river, which I'm phenomenal at reading rivers. Not bragging, not to hit my own horn.
Not to brag.
I'm just amazing at reading rivers. Continue.
Well, so the Appalachian Mountains, which is the oldest mountains, at least here in North America, they formed during Pangea. And what I learned not that long ago is the Appalachians, or what we call the Appalachians, are the exact same mountain range that formed the Scottish Highlands. Then we just broke apart and drifted away from each other.
But our mountains are the same. They're sister mountains, which was blowing my mind. Sister mountains.
Can we refer to them more often as sister mountains?
Yeah, I just made that up. We can totally just call them that.
That needs to be a thing, sister mountains. I'm pretty Scottish. I mean, not as much as I am German.
No, I got Scottish, too. We'll call it sister mountains. And then this is also when basically all fossils come from, because this is when mostly visible life happens.
So besides those stromatolites, all the other fossils formed in all these different types of rock. This is kind of the timeline of how all these rocks and stuff formed. But as they did, as land started to form, so did different types of rocks.
So it's not just a rock is not just a rock, as much as a lot of us look at a plant, and people are like, a plant's a plant, a rock's a rock. But there actually are different types. As Katy mentioned in the very, very beginning, there are three main types.
But it's not just rocks, it's also minerals. So really quick, what is the difference between a rock and a mineral? Well, a mineral is something that is naturally occurring, so it's not man-made.
It's inorganic, means it's not living, element or compound having an orderly internal structure, usually that's formed into crystals.
Usually.
Yeah, usually. And it has a very characteristic chemical composition. Everywhere that mineral occurs, it's the same.
And it has certain crystal formations and physical properties. But basically, minerals are like the building blocks of rocks. So common minerals that you probably listeners have maybe have heard of before, quartz, that one's the most common mineral on earth.
And it's made from a combination of oxygen and silicone, which I think is crazy to think about.
Yeah, right.
Oxygen?
Yeah.
But that's a gas. But yeah. And depending on what other minerals are mixed in or not what other elements are mixed in with it gives quartz its different colors.
Most of what we see is white, but there is like pink and gray and all sorts of colors. There's also feldspar and mica. We have tons of mica at work.
Calcite, all sorts of things. In all, there are over about 4,000 different minerals that cover our earth. And we actually use these minerals in our everyday life.
So we can utilize just the mineral or we can utilize the rock. And a rock is an aggregate of one or more of these minerals.
It is solid. So it could be a combination of one or more minerals, a body of undifferentiated mineral matter, so just like all the same mineral kind of, or solid organic matter. And that would be coal.
So the aggregate of more than one mineral would be something like granite, so like your granite countertops that you've got at home. That is a mix of quartz, feldspar, hornblend, and mica. So a whole bunch of crazy words, but basically all together they make that granite.
Something that is all the same is obsidian, which, oh, so beautiful.
It really is.
Also known as volcanic glass. It is melted silica, so you can't see the grains anymore. It is literally just like a hardened liquid.
Freaking gorgeous.
I was going to say, which is probably why it's so pretty.
Yeah, yeah, exactly. And then coal, like I said, is that solid organic material, which is still considered a rock, which I don't think I knew that. I don't think I knew that coal was considered a rock.
I don't know what I would have considered it, but...
Really?
Yeah, I don't know. I don't know.
You can't be a rock. You're soft.
And you can burn it.
And you can burn it. You can burn... You can be burned and you're soft.
You're clearly not a rock.
Not a rock. But yeah, coal is compressed plant matter from millions of years ago. It's just fossils.
So now that we know what a rock is, what are the three types that Katy mentioned? They are the igneous, the sedimentary, and the metamorphic. And I don't want to bore anyone to tears, but I do think it's kind of cool, so I'm going to go a teensy bit deeper.
Believe me, guys, there is so much more on this.
Well, I mean, there's a whole field of study on it, so...
Yeah, yeah. Um, so the igneous rock. What are they?
Those are rocks that form either above or below the Earth's surface from molten rock material, so they are what comes from being super duper hot. They're typically the hardest and the heaviest of rocks, and there are over 700 types. Um, the texture of that rock depends on what minerals make it up and how quickly it's cooling.
So, like, if it cools really fast, they're gonna have really tiny little grains that didn't have time to grow. If they cool really slowly, they're gonna have big large grains and big crystals. And so some examples of igneous rock is, again, that granite that I mentioned just a second ago.
So granite forms under super duper heat. And pumice, that really weird, like, holy porous stone. The holy...
The holy... The holy porous stone! But yeah, pumice, it's what, you know, like, they can sell them so you can, like, scrub your feet with them, right?
Isn't that, like, a thing? Um, yeah, so, igneous, super hot, and then, of course, that... things can be broken down even further.
There's, like, the extrusive igneous rocks, which are ones that explode from volcanoes, which who doesn't think... I mean, come on. That's pretty sweet.
And then, the intrusive igneous rock, and that's what forms underneath of the ground when magma cools down there. Huge big crystals. Okay.
Then, we have the sedimentary rock. This is rock resulting from the consolidation or forming, like, compaction of loose sediment that accumulates in lots and lots of layers. So think about this as, like, when the dust settles, basically, then that hardens, and then it hardens, and then hardens, and then hardens again and again and again.
So these rocks actually are really cool because they give great clues to the past. For example, sandstone is a type of sedimentary rock, and it's made up of, you guessed it, sand.
It's sand.
And that's probably where most people would leave it. But if you think, hmm, what environment do we find sand in today? The beach or a desert?
So that's how you know this used to be a beach or a desert here. And so we can kind of piece together how the world used to look based on these sedimentary rocks. There's a couple of different types of sedimentary rocks.
There's conglomerate, so that's just a whole bunch of fragments of older rocks forming together. Limestone, which Katy and I are really familiar with because in our part of the country, most things are made of limestone.
It's freaking everywhere.
Yeah, and that is, it actually consists of the remains or secretions, terrible word.
Yeah, right?
Of marine plants and animals. So a limestone, again, is very fossil-like. It's just the remains of dead stuff.
But because it's made of that dead stuff, it erodes very easily, and so that's where your caves and stuff are coming from, our limestone. And please, let's do an entire cave geology episode.
Dude, that would be awesome.
Yes.
But I want to go to the cave to do it. I will meet you at Mammoth Caves. I feel like that's halfway.
Me too. I feel like that's halfway, almost, from me to you. That's probably about halfway.
I'll meet you in a cave.
And that will be our... Just crawling through.
That would be such a funny episode. Just you and me going through a cave. We need to make this happen.
I don't care where. I will fly anywhere to make this happen. We have tons of caves up in Pennsylvania.
I will fly to make this happen. That would be so funny. But no, us splunking...
Okay, we're going to revisit this. Continue, because this has to happen.
We'll have our little GoPros on the front.
Just the audio alone would be hilarious, because...
Katy, move your butt out of the way.
My boobs are too big. They're smushed. What touched me?
We're making it happen.
I seriously don't care if I had to fly up to see you. We are making it happen.
We got a ton of them here. Some other sedimentary, sandstone and mudstone, which I didn't know was a thing. Real original names there.
Scientists, sandstone, mudstone.
They're geologists.
Yeah, that's true. Mudstone is literally just made from old mud. And then shale is actually a different type of sedimentary rock.
I thought that was mudstone, but it's not. Shale is its own thing. But shale is famous for having fossils in it.
Again, where we're from.
Talking about, yes, for sure there, because I definitely find trilobites in that area. But also the Marsala shale, which is in Canada, which again, you're talking about very, very old. Yep, that is where some ancient fossils are found, and so freaking many of them.
And the Marsala shale, that goes down into Pennsylvania because that's where all the fracking and everything, all the natural gas is in there.
And then of course, and also in our part of the world, is where tons of coal is found. So we live in a very geologically rich area, is the Northeast in general.
I do miss some aspects of it. I mean, I love Texas, don't get me wrong, but yeah. The difference of geology and things like that up there, I guess it's just a little bit more evident.
Yeah, and it just seems so old. But we also know because of all the limestone and the sandstone and things like that, again, we can read these context clues to know that we were part of that, a great inland sea back in the day. So back in Pangaea, when things started to split apart, very shallow oceans were formed in there where Katy's octopus probably lived.
And that would be where all the, like we can see evidence of, yeah, we used to live in the ocean.
Yeah, tropical no less.
Yeah, that's crazy. Okay, and then last type of rock is the metamorphic rock. And so this is a rock that is modified by heat, pressure, and chemical processes, usually while buried deep below the Earth's surface.
So this one's like the most complicated one because it's just formed like, well, the sedimentary one's pretty complicated because there's all different types of sedimentary, clastic, biologic, chemical.
Yeah, but it's how this one forms, I think, is weird because it's like either increasing temperature and...
Yeah. It doesn't seem as straightforward.
Yeah, no, it's definitely not.
So there's two different types of metamorphic rock. There's foliated, which means that's pressure, squeezing real hard, and forms like big plates of stuff. Like the crystals are formed into plates.
And again, Appalachian Mountains, that's a rock called like Gneiss. It's G-N-E-I-S-S, which is weird, but it says Gneiss. And then the non-foliated, they've got plenty of like different minerals that form different crystal structures.
And that's where you get marble and soapstone. So again, that's a soapy stone. So their crystal structures are just super, super different.
And that's actually that type of rock is what is under like DC.
But yeah, so that is all the different types of rocks, the difference between a rock and a mineral. You guys can dive way deeper into that if you'd like to. It's really cool stuff, so I highly encourage you to do it.
And if you're interested, there are different geological maps of different areas of the world. And you could like specifically look up what is the geologic profile of the area that you live in.
And not only that, but once you look at the geological profile, then you can start to look into the fossils that are found in your area and what era and where. And it's just, yeah.
Yeah, and the end, and you can start reading the landscape, like Katy talked about and is probably going to talk about next, because knowing what types of rock, that rock affects everything that grows there. The way the landscape is formed and fashioned, it dictates nature.
It really does.
If you know your rocks and your geology, you know what you actually should be able to find there, because it affects the type of soil and acidity. Everything. It all comes back to rocks.
To rocks.
Geology, which is definitely one of the most picked on.
Yeah, underappreciated science.
By the other science fields, for sure.
I feel like it's not glamorous, other than the gem aspect.
True, true. All righty. So after my Getting to Know Hell 101 class, Haiti on Crash Course, and how geology kind of affects everything, I'm going to do sort of like a flashback to our river episode.
So in Season 3, Episode 3, titled How We Influence Waterways, I talked about the Colorado River. So yet again, digging deeper into some of this, like what Laura talked about, how stuff affects other things, from a geology perspective, I'm going to talk about a river's role within geology, the importance of it, and how this does affect us. And this section once again has stuff in it.
I had no clue, which was a lot of the 101. I went down a deep rabbit hole for Geology 101 that I couldn't get, it was just too deep to get into for here.
Well, right, and I'm sure you had to choose what's actually relevant and what's just extra.
It was like, I'm talking like a 2 a.m.
rabbit hole.
So I was deep in the abyss of a rabbit hole. Alright, so first, let's backtrack a little bit. So what is a river?
I know this is ridiculous, but just hang it with me. Alright, so a river forms from water flowing from a higher elevation to a lower elevation, all due to gravity, of course. When rain falls on the land, it either seeps into the ground or becomes runoff.
And again, seeps into the ground, that's very negated. Yeah, on geology and where you are. So when rain falls on the land, it either seeps, like I said, into the ground or becomes runoff, which flows downhill into rivers and lakes on its journey towards the seas.
In most landscapes, the land is not perfectly flat. Of course, it slopes downhill in some direction. Flowing water finds its way downhill initially as small creeks.
As small creeks flow downhill, they merge into form larger streams and rivers. Rivers eventually end up flowing into oceans. So, geology tie-in.
Let's do this. All right, water, pulled by gravity, forms rivers. We just went over that.
If it's pulled by gravity, it's always going to be looking for the lowest point wherever it is, whether at the top of a mountain or the flattish plains. Other times, it's a little more hardcore. So, rivers and the systems they make up are called fluvian systems.
In Latin, fluvius just means river, which is one of the few Latin words I can pronounce. When talking about fluvial systems, this means river systems, which are the most important geomorphic agent or the study and origin of the evolution of topographic and... What is bathymetric?
I didn't even look this up. Anyway, it's features that are created by physical, chemical, or biological processes operating at or near the Earth's surface. So, geological processes happen slowly over time, and water has a huge role in this process.
But it's not the only thing that plays a role. Ice, wind, and just natural gravity also help in the movement, breakdown, erosion.
I always think of, is that from Liar Liar? Something about, he's talking about, like, he's like, erosion, erosion, it's that race, Ventura. It's definitely one of them.
Yeah, it's definitely one of them. I can't remember. So anyway, there's the movement, breakdown, and deposition of sediment, and what are made up of sediments, rocks, sedimentary rocks.
It just takes a really long time for wind, let's say, to break things down, or for water to carve through something like the Grand Canyon. So let's take a look at the Grand Canyon because it's an extremely visible example of the relationship of geology and rivers. And thank you, National Park Service, for your perfectly interpreted information on the Grand Canyon.
I was going to say, and they have so, they have killer information on the Grand Canyon. On all rock stuff.
Dude, that's what I'm saying. If you want a very basic, good presentation. I've never been to the Grand Canyon, but just even their online information, as far as geology goes, Grand Canyon.
They have an entire rocks and minerals section on their website.
Yeah, they killer. Anyway, so about two billion years ago, the canyon area around the Grand Canyon started to form with the formation of igneous and metamorphic rocks of the inner gorge. Now remember, as sediment is laid on top of old rocks, lowest, oldest is at the lowest, newest is near the surface.
Above these old rocks lay layer upon layer of sedimentary rock, and each of the layers can tell us about what happened around that time in history. So between 70 and 30 million years ago, with the help of plate tectonics I talked about earlier, the whole region was uplifted, resulting in the high and relatively flat Colorado Plateau. It wasn't until 5 to 6 million years ago, and I say that like it's a baby, but it really is compared to some other things.
Little baby.
So about 5 to 6 million years ago, the Colorado River started to form due to downcutting, weathering, and erosion. So downcutting occurs as a river carves out a canyon or valley, cutting down into the earth and eroding rocks away. So downcutting also, though, happens during flooding, which happens all the freaking time in the Colorado River, like to terrifying proportions.
Let's see here. During flooding, when large amounts of water are moved through the river channel, large rocks and boulders are carried too, because this is where you get those flash floods in the canyon.
Big old chunks are breaking up.
Which is terrifying because, yeah, man, it's just scary. Anyway, completely flash floods are unpredictable sometimes. So these rocks that are being carried by the water basically act like chisels, chipping off pieces of the riverbed as they bounce along.
Further erosion of the canyon was also done by tributary streams, which led to the canyon's widening, which is why it's so long. So not only over time is it cutting down, but the reason why it's so wide is because it's spreading out. So it's spreading out, it's cutting down, all to make this huge canyon.
So as the canyon itself started forming, the metamorphic and igneous rocks 2 billion years ago, but the river itself didn't... so the canyon itself is about 2 billion years old, but the river itself didn't start helping to carve the canyon that we know it as until about 5 to 6 million years ago, sorry, which is a fairly young river. Now, if you were to guess where some of the oldest rivers in the world are, because remember, rock is older than water, but the rivers anyway, you'd probably think that some of the oldest rivers are someplace like the Nile, right?
I mean, it would kind of make sense. If it was so big. Yeah, if it was so big, between 70,000 to 100,000 years ago is when homo sapiens started migrating from the African continent and populating parts of Europe and Asia, so the Nile would be a great guess.
But remember, although humans have heavily relied on rivers, animals are older than humans, and rocks are even older than that, of course. So, the top five oldest rivers in the world, three, are found here in North America.
Oh, cool.
The French Broad River in Tennessee is number five. Oh, wait. Oh, wait.
It's all here, isn't it?
And formed around the same time, coming in at number three and number four is the new river that flows northward from South North Carolina to West Virginia. And the Susquehanna River in Western PA is also insanely old, which I had zero clue that the Susquehanna River was one of the oldest rivers in the world.
But I get it, totally.
In the world.
Appalachian Mountains are the oldest mountains in the world.
See? And so that's what I'm saying. So again, geology.
So the Grand Canyon, if you think about the Grand Canyon, like yes, it's young. It's a very young river, but it's also like very abrasive because of the geology and where it is formed. It's very like cut.
They're very hardcore. So of course it's going to be young because it's pounding those rocks very quickly. Where someplace like the Susquehanna, yes, it's at the kind of like at the bottom ish of the mountains of the Appalachian Mountains, but it's very meandering rolling hills.
It's just kind of meandering along.
And so more gentle, of course, wide and shallow.
It's very wide and shallow. So of course, it's going to be super, super old.
So that and I guess like it would depend. So the sedimentary rock, I'm pretty sure if I remember geology a little, sedimentary rock erodes pretty quickly. Whereas some of the super hard, like metamorphic rock, no.
Correct.
The bedrock of the Susquehanna is the like not eroding.
It's sedimentary rock. But it's still just because it's so gentle and so slow. It's geology.
It just takes forever. Because really the only area within Pennsylvania that would be more metamorphic and igneous rocks are confined to like the southeast, far southeast portion of the state. But the geology around the Susquehanna, again, is gentle rolling hills and mountains.
And for the most part, it's an easy flowing river, which is why in comparison to some place like the Grand Canyon, they're very drastically different because it's all based upon the geology.
Pennsylvania does have the Grand Canyon of Pennsylvania.
It does. We do.
I've been there.
It's not as exciting.
Not at all the same.
No, not as exciting, but it is pretty cool. I think that's also like a certified dark space, if I'm remembering correctly.
That's cool.
I do know in Pennsylvania, which is one of the very, very few places, I think it's called Cherry State Park. It's in north central PA. I think it's Cherry.
Anyway, it's one of the few dark, certified dark skies in northwestern PA, because there's so many huge cities up there. Anyway, so while rivers are affected by geology, of course, and then rivers in turn affect and erode rocks, they both have a huge effect on us. So if you look throughout history, rivers and geography, along with geology of the region, have played key roles for humans for more than just food.
Natural protection and battle, of course, transportation once humans figure out floating was a thing. And truly the lifeblood of every civilization is the resource management of not only the rivers themselves, but the land and what is found beneath the surface is important. People, yes, have moved to follow rivers, which keeps them and their food sources alive, but they have also followed the underground resources, which typically you can get to and see easier at rivers before drilling into earth's surface was a thing.
I mean, think about how, I mean, geology, we use so many geological products every single day.
So, and I mean, today geology is often talked about when discussing even energy sources, like coal versus wind versus gas, as we talked about earlier with the shale. But geology also affects things like the gold and materials that are in our computers, cell phones, and everything else that seems like we're being affected with the chip shortage.
Geology is supposed to be based on?
Well, yeah, supposed to be. Not anymore. But even something like fluoride in our toothpaste, our food sources, and of course the water, all affect us today.
And we have largely in part to thank geology for that. Geology is more than just rocks, and understanding geology and the history of it is just that, the history of us and our world, and how it operates and exists. So we will definitely, definitely, definitely have to do more episodes about geology, because we literally, I mean, we can break this, no pun intended, into a bajillion different ways, and we literally just scratched the surface with this episode.
Yeah.
Man, my geologist. Shout out to one of my naturalist friends who gave me a lot of the information for this episode, Catherine, who is a geologist. She's gonna be so proud of us for this episode.
Geologists, the unsung heroes, that all the rest of us... Well, it reminds me too about how people feel about botanists, you know, at least like a lot of...
From the biology people.
Yeah, from the natural sciences point of view, everyone's like, but everything is tied together, or it's based on something. Like your animal communities are based on your plant communities. Your plant communities are based on the soil, and your soil is based on the geology.
But in all seriousness, if there's a geologist out there that wants to take us spunking, please do. Because we need to make this happen.
I follow an Australian geologist guy on TikTok.
Oh, was that the... I don't have my TikTok thing anymore, but I know who you're talking about. Who gives really good information.
Very, very interesting. Alrighty, well that's Geology 101 in a nutshell. Or in a something.
In a geode? Yeah, let's do it in a geode.
It's the same concept.
In a geode. So hopefully you guys learned something. That geology really, it affects us every single freaking day.
The fact that we're even living, we have geology. Thanks, rocks. Alright, hopefully you guys listen.
Make sure to follow us on social media. But even more so important, follow us on Patreon. So that we can get more supporters, so that we can actually keep...
Listen, if we get enough supporters to pay for us to go to Splunking, I will make it worth every last one of your pennies. I promise.
Well, that plus we also would really like to start merch.
No, we would.
Next season. And it's going to be really hard to do without some initial capital.
Yeah.
If anybody wants to sponsor us for some stickers.
Or a Splunking trip.
Or a Splunking.
We need to make this happen.
What we should do is we should host, like, if anybody wants to come on trips with us, they just have to pay for us too. But if they did, I would absolutely guide you anywhere in this natural world.
I will guide you. I will guide you anywhere in this natural world if you will pay for me. Listen, I mean, listen, we've given tours, like, our entire professional career.
I will interpret the bejeezer out of whatever we are looking at.
Also, I pride myself that I am a phenomenal backwards walker. So, we will interpret the bejeebers out of you and do it walking backwards flawlessly. Just sponsors to go on a trip with you.
We are all for it. We're here. We're here for all of your interpretive needs.
All right, everyone, go check us out on Patreon. Until that, we will talk to you next week.
See you next week.