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What's in a Name? Volcano Edition · PlanetGeo: The Geology Podcast

• 0:07
  SPEAKER_00: Welcome to Planet Geo, the podcast where we talk about our amazing planet, how it works, and why it matters to you.
• 0:30
  SPEAKER_02: Chris.
• 0:31
  SPEAKER_02: Hey.
• 0:33
  SPEAKER_02: How are we doing?
• 0:34
  SPEAKER_02: Oh hey.
• 0:34
  SPEAKER_02: Oh hey, hey, good hey, how's it good to see you?
• 0:37
  SPEAKER_02: How are you doing today, Jesse?
• 0:39
  SPEAKER_02: I'm good.
• 0:39
  SPEAKER_02: How are you today?
• 0:40
  SPEAKER_02: I'm great.
• 0:40
  SPEAKER_02: I'm ready to roll.
• 0:42
  SPEAKER_02: Let's do it.
• 0:42
  SPEAKER_01: So, Chris, first of all, this is this is something you're interested in, and I'm interested too, but this is something you brought to the table here.
• 0:50
  SPEAKER_01: I did.
• 0:51
  SPEAKER_02: Yep.
• 0:51
  SPEAKER_01: So lead us in.
• 0:53
  SPEAKER_01: What are we talking about and why are we talking about it today?
• 0:56
  SPEAKER_03: Um, I don't know.
• 0:57
  SPEAKER_03: This kind of scratches an itch.
• 0:59
  SPEAKER_03: Like I want to get Uh oh.
• 1:01
  SPEAKER_01: Scratches an itch.
• 1:02
  SPEAKER_01: That's always you never know where we're gonna go with a scratches and itch here.
• 1:06
  SPEAKER_03: I know, but I just wanted to do just kind of an episode just on volcanoes in general, just general volcanism stuff, right?
• 1:13
  SPEAKER_03: And so there's that.
• 1:15
  SPEAKER_03: And then uh I was begin putting this together and thinking about it.
• 1:18
  SPEAKER_03: Uh I'm struck with this thing about you know, the way that volcanoes are taught in a typical intro class is quite often it's just it leads to confusion, at least so this is an intro to geology class that you take in college or the class you taught me in high school.
• 1:36
  SPEAKER_03: Right.
• 1:37
  SPEAKER_03: And in fact, when I taught you in high school back a long time ago, I've changed the way that I do this because the way that I taught you, the the system just doesn't work.
• 1:48
  SPEAKER_03: But let's start with some introductions.
• 1:49
  SPEAKER_03: You are Dr.
• 1:50
  SPEAKER_03: Jesse Rymick.
• 1:51
  SPEAKER_03: You are one of my former high school students, one of the best, I might add.
• 1:55
  SPEAKER_03: Um you went on to get your yeah, you went on to get your PhD um in geology and now work as a professor at Penn State University in the geoscience department.
• 2:06
  SPEAKER_01: That's right.
• 2:06
  SPEAKER_01: And you're Chris Bullheis, nationally recognized earth science teacher.
• 2:10
  SPEAKER_01: You teach earth science, geology, field geology, astronomy.
• 2:14
  SPEAKER_01: You teach tons of stuff, coach tons of stuff.
• 2:16
  SPEAKER_01: You've been at it for a long time, I think.
• 2:19
  SPEAKER_01: And uh, we've been friends for a while now, basically ever since I kind of got on the latter side of college.
• 2:24
  SPEAKER_01: And this is Planet Geo, where we talk about geoscience stuff, interesting geoscience stuff and why it matters.
• 2:29
  SPEAKER_01: So we're talking about classifying volcanoes or how to describe or talk about volcanoes or different volcano types on Earth, right?
• 2:37
  SPEAKER_01: I mean, that's kind of the the thing we're gonna get into a little bit.
• 2:41
  SPEAKER_03: Right.
• 2:41
  SPEAKER_03: We're gonna begin with that, with the typical like the three category classification system, and and I've got some just thoughts on why that doesn't really work and why that's probably not the best way to do things.
• 2:53
  SPEAKER_03: And then we're just gonna get into talking about all of the other types of volcanoes that we have on this planet.
• 3:00
  SPEAKER_01: Yeah, so that's really interesting, you know, that you've changed, I guess, your approach since I was in class, which is a while ago now.
• 3:07
  SPEAKER_01: So maybe you know things change in 15 years, I suppose.
• 3:10
  SPEAKER_01: But I think the reason that they change, that's an interesting one.
• 3:13
  SPEAKER_01: So your sense is that it's too simple or it's not actually a great classification scheme.
• 3:19
  SPEAKER_01: Is that right?
• 3:20
  SPEAKER_03: Yeah, I think you know, I get it.
• 3:22
  SPEAKER_03: We have this need to, you know, as humans, it's kind of human nature to put things in categories and uh you know put them in a box, and you know, so this is this kind of volcano and and this is this kind of volcano based on the geomorphology and the the chemical composition and um the way that it's kind of personality with the way that it erupts and so on.
• 3:43
  SPEAKER_03: But it's just every intro-level textbook uh basically has three ways of classifying volcanoes, but there are so many exceptions that it leads to confusion.
• 3:59
  SPEAKER_01: Sure.
• 4:00
  SPEAKER_01: And this is a a problem, I think, in probably most fields of science, and I mean, as you said, all of human life, but it's particularly sort of rife in geology or geoscience because you know, every river is slightly different, even though there are broad classifications for river types and river morphologies and how they behave.
• 4:19
  SPEAKER_01: And so I like this, and it kind of highlights another thing for me that when I was going to graduate school, you sort of start to realize how the textbook is maybe not wrong, but is an oversimplification of the real world.
• 4:33
  SPEAKER_01: You know, your your textbook that you sort of are taught this is right, this is the source of what's right.
• 4:38
  SPEAKER_01: And it's actually uh a sort of a very simplified version of the real world.
• 4:42
  SPEAKER_01: And the real world is pretty complicated out there.
• 4:45
  SPEAKER_01: So I'm excited about this, Chris.
• 4:47
  SPEAKER_01: And I think you know, it brings up another thing.
• 4:49
  SPEAKER_01: When we interviewed Dr.
• 4:50
  SPEAKER_01: Diana Roman a long time ago, who's a volcano seismologist, studies sort of the voices of volcanoes or the sound waves they give off, she said that volcanoes are like snowflakes and each one is unique.
• 5:00
  SPEAKER_01: And I think we're gonna kind of highlight that point a little bit here in this episode.
• 5:05
  SPEAKER_03: Yeah, and I think too, you know, you touched on the part about the textbook and how they're maybe not wrong, but just um uh not as thorough as they could be in any given topic, right?
• 5:17
  SPEAKER_03: With this three category system of classifying volcanoes, it's okay that we do that, but I think that it needs to be as an addendum stated that not everything fits into this neat little system that we've devised here.
• 5:32
  SPEAKER_03: I think just that students need to know that, that it's not as simple as that.
• 5:37
  SPEAKER_01: So that's what we're gonna kind of dive into today.
• 5:39
  SPEAKER_01: And so, Chris, what are the three categories that you taught me that you no longer teach in class?
• 5:44
  SPEAKER_03: So there are shield volcanoes, and they're called that based on their geomorphology or how they look.
• 5:50
  SPEAKER_03: Okay, they look like a warrior shield lying flat.
• 5:52
  SPEAKER_01: Let's describe that a little bit more because that's not something people typically associate with volcanoes.
• 5:57
  SPEAKER_01: Like, you know, we think of volcanoes as the point, you know, the the sort of peak, and we that's how we envision volcanoes.
• 6:02
  SPEAKER_01: But shield volcanoes are the one that people don't often sort of recognize as volcanoes, but this is like Hawaii, right?
• 6:09
  SPEAKER_01: It's this really broad, rounded hill.
• 6:12
  SPEAKER_01: Very gentle slopes, yep.
• 6:14
  SPEAKER_01: Very gentle slopes, very broad, big hill, basically.
• 6:18
  SPEAKER_01: Mountain, really, that gets built up.
• 6:20
  SPEAKER_01: Um, and you said it looks like a warrior's shield turned upside down, right?
• 6:24
  SPEAKER_03: Or not upside down, lying flat.
• 6:26
  SPEAKER_01: Like Captain America's shield, like turned upside down.
• 6:30
  SPEAKER_03: Perfect.
• 6:30
  SPEAKER_03: Yep.
• 6:31
  SPEAKER_03: We'll go through each one of these.
• 6:32
  SPEAKER_03: They're gonna be in the systems that we're gonna talk about as we go through this episode, too.
• 6:37
  SPEAKER_01: Okay, so you what you teach now is the three plus more, basically.
• 6:40
  SPEAKER_03: Yes.
• 6:41
  SPEAKER_03: So then you have the what are called strato volcanoes, or they're often referred to as composite volcanoes.
• 6:46
  SPEAKER_03: And these are the ones that we have in the Pacific Northwest, you know, Northern California, Oregon, Washington, and up into Canada.
• 6:53
  SPEAKER_03: Um these classic, yeah.
• 6:57
  SPEAKER_01: These are the ones that if if you are thinking of a volcano, this is what you're picturing, right?
• 7:00
  SPEAKER_01: This is Mount Fuji, this is Mount St.
• 7:03
  SPEAKER_01: Helens, you know, Mount Rainier, all those ones.
• 7:06
  SPEAKER_03: Absolutely.
• 7:07
  SPEAKER_03: And then you have cinder cones, and that's the last of the three categories.
• 7:10
  SPEAKER_03: And cinder cones are usually they're made up of what we call pyroclastic material, which pyro means fire, and clastic means fragments.
• 7:19
  SPEAKER_03: You know, these are, you know, um, I don't know how to decide to say it.
• 7:23
  SPEAKER_03: Like you can feel free to jump in and rescue me here at any moment, but I zoned out looking at your bald head.
• 7:31
  SPEAKER_01: Pyroclastic?
• 7:32
  SPEAKER_01: Is that what we were talking about?
• 7:35
  SPEAKER_03: Yeah, yeah.
• 7:35
  SPEAKER_03: So cinder cones are made of pyroclastic material.
• 7:38
  SPEAKER_03: These are fragments, and so they're a little bit more explosive than the lava eruptions that you get with shield volcanoes and so on.
• 7:44
  SPEAKER_03: We'll get into all the details here.
• 7:46
  SPEAKER_01: But they're not big, they're they're not voluminous eruptions, they're little pulses spitting stuff in the air, and then it kind of falls down.
• 7:52
  SPEAKER_03: Yeah, and they're and so they're not very big, they tend to be, you know, less than a thousand feet usually um in height, and they tend to occur as like they're almost like parasites.
• 8:03
  SPEAKER_03: They occur on the flanks of larger volcanoes.
• 8:06
  SPEAKER_01: Right.
• 8:06
  SPEAKER_01: And so these are all things that would represent a single volcano that you can see on the surface of the land.
• 8:13
  SPEAKER_01: But there are other things that are actually volcanoes that represent themselves differently on the surface of the earth, right?
• 8:18
  SPEAKER_01: And so we're gonna talk about volcanoes as places where magma, which is liquid rock down in the earth, is being erupted out onto the surface, becoming lava, where liquid rocks are being erupted out onto the surface of the earth.
• 8:32
  SPEAKER_01: That's fundamentally what a volcano is.
• 8:34
  SPEAKER_01: So we're gonna talk about the wide range of things that do this process, erupt liquid rock up onto the surface in some way.
• 8:41
  SPEAKER_03: That's right.
• 8:42
  SPEAKER_03: So go ahead.
• 8:46
  SPEAKER_03: No, go ahead.
• 8:46
  SPEAKER_03: No, go ahead.
• 8:48
  SPEAKER_02: No, no, you go.
• 8:50
  SPEAKER_02: No, you go.
• 8:51
  SPEAKER_03: You're such an idiot.
• 8:53
  SPEAKER_03: Okay, why do I do this with you, honestly?
• 8:55
  SPEAKER_03: Can you please tell me?
• 8:57
  SPEAKER_01: Beggars can't be choosers, as it were.
• 8:59
  SPEAKER_01: Um so why is this three category system, shield volcanoes, composite cones, and cinder cones, why is that not quite uh descriptive enough or not quite useful enough?
• 9:08
  SPEAKER_03: Well, you know, because it's not inclusive enough.
• 9:12
  SPEAKER_03: There are so many volcanoes that don't fit into this.
• 9:16
  SPEAKER_03: Like I said, you know, to students that can be confusing.
• 9:18
  SPEAKER_03: They're like, well, what what does Yellowstone fit into?
• 9:21
  SPEAKER_03: When they realize that Yellowstone's a volcano.
• 9:23
  SPEAKER_03: What about Yellowstone?
• 9:24
  SPEAKER_03: Where which one is that?
• 9:25
  SPEAKER_03: Well, it doesn't fit.
• 9:26
  SPEAKER_03: It's none of them.
• 9:27
  SPEAKER_03: What about these massive flood basalts?
• 9:29
  SPEAKER_03: You you and I went out to when we were in Oregon a number of years ago, we went out to the Columbia River flood basalts and and um you know had a great time, but you know, that's a that's volcanic and it doesn't, it's not a shield volcano, uh, you know, and then what it what about mid-ocean ridges?
• 9:47
  SPEAKER_03: You know, these are the most extensive volcanic systems in the world, and they don't fit into this category.
• 9:53
  SPEAKER_01: These are the underwater volcanic systems that are in the middle of most ocean basins and are forming new oceanic crusts.
• 9:58
  SPEAKER_01: Yes.
• 9:59
  SPEAKER_01: So uh okay, so these things, it's not inclusive enough.
• 10:01
  SPEAKER_01: The the three category system doesn't describe all volcanoes well enough, doesn't include all volcanoes in them.
• 10:09
  SPEAKER_01: Okay.
• 10:10
  SPEAKER_01: I would say, Chris, let's um let's get into it, shall we?
• 10:13
  SPEAKER_01: Let's go through the the categories, let's describe these volcanoes, and then let's add some addendums to different volcano types that that we actually have on Earth.
• 10:22
  SPEAKER_03: Right, let's go.
• 10:23
  SPEAKER_03: But even with what we're doing, this is a rabbit hole.
• 10:26
  SPEAKER_03: I mean, we you can keep going and going and going.
• 10:28
  SPEAKER_03: And Diana Roman, I mean, it was a perfect statement because it's so true.
• 10:33
  SPEAKER_01: And it's also useful to understand various categories, to understand how things are similar and also how things are different from one another.
• 10:40
  SPEAKER_01: So let's dive in.
• 10:42
  SPEAKER_03: So, Jesse, let's jump into talking about the expanded category list of volcanoes that we get on this planet.
• 10:49
  SPEAKER_03: So, let's talk about what do they look like?
• 10:51
  SPEAKER_03: What's their geomorphology?
• 10:53
  SPEAKER_03: Why do they look that way?
• 10:55
  SPEAKER_03: Okay.
• 10:56
  SPEAKER_03: And then we'll talk about, you know, what their personality is, the nature of their eruptions.
• 11:01
  SPEAKER_03: Are they violent?
• 11:01
  SPEAKER_03: Are they quiet?
• 11:02
  SPEAKER_03: Are they somewhere in between?
• 11:04
  SPEAKER_03: And then from a geoscience perspective, where do they tend to occur?
• 11:09
  SPEAKER_03: And then finally, we'll talk about some examples.
• 11:11
  SPEAKER_01: Perfect.
• 11:12
  SPEAKER_01: All right, so we got five things.
• 11:13
  SPEAKER_01: We're gonna go through a bunch of different categories here.
• 11:15
  SPEAKER_01: The first one, Chris, we're gonna start with shield volcanoes.
• 11:19
  SPEAKER_01: And these are the warriors' shield or Captain America's shield lying on the ground.
• 11:24
  SPEAKER_01: They're very gently sloping edges, and these volcanoes are massive.
• 11:30
  SPEAKER_01: These things can be giant.
• 11:32
  SPEAKER_01: So, just as one example, the Hawaiian volcanoes, Mauna Loa, is 13,000 feet above sea level, over 13,000 feet above sea level.
• 11:41
  SPEAKER_01: But that volcano actually extends from the bottom of the ocean floor, and that volcano has been built up for 20,000 feet to even reach sea level, and then another 14,000 feet above sea level.
• 11:52
  SPEAKER_01: So these things are enormous.
• 11:55
  SPEAKER_01: I mean, the volcano size is a giant.
• 11:58
  SPEAKER_01: That's the way they look, is this shield.
• 12:00
  SPEAKER_01: And so, Chris, why do they look that way?
• 12:02
  SPEAKER_03: Yeah, the the reason why they look the way they look is because they're made of the rock basalt.
• 12:06
  SPEAKER_03: Basalt's an igneous rock, it's black, it's fine-grained, which means that the lava cooled on the surface of the earth rather fast.
• 12:15
  SPEAKER_03: Basalt is very fluid.
• 12:18
  SPEAKER_03: In geology, we call this low viscosity.
• 12:20
  SPEAKER_03: And I kind of like I use the analogy of pancake batter.
• 12:24
  SPEAKER_03: Okay.
• 12:24
  SPEAKER_03: If you take pancake batter and pour it onto a hot skillet, you can get different shaped pancakes dependent upon how fluid you make the batter.
• 12:32
  SPEAKER_01: Right.
• 12:33
  SPEAKER_01: And I just want to clarify here that we're talking about the lava that comes out, and it is liquid rock, and it is sort of basaltic lava that crystallizes to form basalt the rock.
• 12:42
  SPEAKER_01: So we're kind of using these terms here just to keep everybody on the same page.
• 12:44
  SPEAKER_01: We're talking about the liquid rock that comes out that then crystallizes into rock.
• 12:48
  SPEAKER_01: All right, great pancake analogy, Chris.
• 12:50
  SPEAKER_01: Let's hit it.
• 12:50
  SPEAKER_03: Okay, so that lava, you can think of it as pancake batter.
• 12:53
  SPEAKER_03: If you make a batter really thin and runny, you add a lot of water to it, for instance, or a lot of milk to it, pour it on the skillet, it's gonna form a very flat, broad shaped pancake, right?
• 13:04
  SPEAKER_03: Because it's not, you pour it out, it's gonna run like a flood.
• 13:07
  SPEAKER_03: Okay.
• 13:08
  SPEAKER_03: If you take thick batter, it'll tend to mound up and not flow.
• 13:11
  SPEAKER_03: Well, this these shields are made up of really, really runny lava.
• 13:15
  SPEAKER_03: And so that's why it's shaped the way it is.
• 13:18
  SPEAKER_03: That's everything to do with viscosity, the resistance to flow that the lava has.
• 13:24
  SPEAKER_03: That also speaks to its eruptive personality, too, right, Jesse?
• 13:29
  SPEAKER_01: Yeah, that's right.
• 13:30
  SPEAKER_01: And because this lava is so runny, it also means that it doesn't get really clogged up in the volcanic plumbing system very much.
• 13:39
  SPEAKER_01: So you can basically erupt a large volume of basaltic lava very quietly, if that makes sense.
• 13:47
  SPEAKER_01: I mean, on the human scale, no volcanic eruption is really quiet.
• 13:51
  SPEAKER_01: I mean, it's all very traumatic on the human scale, but compared to other volcanoes, this is relatively quiet.
• 13:57
  SPEAKER_01: You can push a lot of volume of stuff up very sort of passively.
• 14:02
  SPEAKER_03: Yeah, you said before that these things are massive volcanoes, and so you can think of shield volcanoes as gentle giants.
• 14:10
  SPEAKER_01: All right, there you go.
• 14:10
  SPEAKER_01: That's a good one.
• 14:11
  SPEAKER_01: I like that one.
• 14:12
  SPEAKER_01: Gentle giants.
• 14:13
  SPEAKER_01: There we go.
• 14:13
  SPEAKER_03: Yeah, they have very quiet kind of eruptions, at least from a volcanic perspective.
• 14:19
  SPEAKER_01: Yes, from from our perspective, everything looks very, very true traumatic.
• 14:24
  SPEAKER_01: But um, okay, Chris, where do these where do shield volcanoes often occur?
• 14:28
  SPEAKER_03: Yeah, they're often found associated with hot spots, and hot these are hot spots that are below oceanic plates.
• 14:35
  SPEAKER_03: Okay, and if you go back to our plate tectonics episode, we talked about the different types of crust and so on.
• 14:41
  SPEAKER_03: That's often where they're found.
• 14:43
  SPEAKER_03: But you we can get some shield volcanoes that are associated with subduction zones where one oceanic plate is diving below another plate and so on.
• 14:52
  SPEAKER_03: So it's usually hot spot, but not always.
• 14:55
  SPEAKER_01: Yeah, and basically you need to have a large supply of basaltic lava.
• 14:59
  SPEAKER_01: So places where you generate that, you get a shield volcano, and hot spots are a very good place to generate a lot of basaltic lava.
• 15:08
  SPEAKER_01: And a couple examples, we've mentioned Hawaii already.
• 15:10
  SPEAKER_03: Yeah, but hey, you went to the Galapagos Islands uh uh when you were a student.
• 15:15
  SPEAKER_01: I did, yeah, that's another great example.
• 15:17
  SPEAKER_03: Did you see Fernandina then?
• 15:19
  SPEAKER_01: Yes, we saw Fernandina, um, and we actually saw the that was the youngest lava flow I've ever seen.
• 15:24
  SPEAKER_01: I think it was like a hundred years old, and I've never been to Hawaii to see things younger than that, I believe.
• 15:30
  SPEAKER_01: Well, how old is Craters of the Moon, Chris?
• 15:32
  SPEAKER_01: I don't actually know.
• 15:33
  SPEAKER_03: Craters of the Moon, the I think the last eruption was about 1400 years ago.
• 15:36
  SPEAKER_01: Okay, yeah.
• 15:37
  SPEAKER_03: So it's recent, but not that recent.
• 15:39
  SPEAKER_01: Not that recent.
• 15:40
  SPEAKER_01: Yeah.
• 15:40
  SPEAKER_01: So there's some very recent eruptions there.
• 15:42
  SPEAKER_01: Um, and yeah, it it looks, you know, when you're we were staying in this boat, you know, there's like 12 students and and a couple of crew people sleeping on this boat throughout the whole trip.
• 15:50
  SPEAKER_01: And when you're like anchored offshore, it is it looks just like a shield.
• 15:54
  SPEAKER_01: I mean, it's a perfect name for these volcanoes.
• 15:56
  SPEAKER_01: So the Galapagos Islands is another uh another great example of shield volcanoes.
• 16:00
  SPEAKER_03: Well, good deal.
• 16:01
  SPEAKER_03: Should we move on to the next type?
• 16:03
  SPEAKER_01: Let's do it.
• 16:03
  SPEAKER_01: What's next, Chris?
• 16:05
  SPEAKER_03: The next category is called strato volcanoes or composite cones or composite volcanoes.
• 16:10
  SPEAKER_03: I prefer the term strato because it says a lot about you know their geomorphology.
• 16:16
  SPEAKER_01: Yeah, it's just a better word than composite volcano.
• 16:18
  SPEAKER_01: I like stratovolcano, it sounds cool.
• 16:20
  SPEAKER_03: Yeah, me too.
• 16:22
  SPEAKER_03: Um, so stratovolcanoes, these are the ones that you typically think of.
• 16:25
  SPEAKER_03: When you think of a volcano, you think of a typical looking volcano.
• 16:28
  SPEAKER_03: It's a stratovolcano.
• 16:30
  SPEAKER_03: These are, to me, I I'm in love with them.
• 16:33
  SPEAKER_03: I I can't get enough of them.
• 16:34
  SPEAKER_01: You know, you really are in love with these volcanoes.
• 16:38
  SPEAKER_01: You are some would say obsessed.
• 16:40
  SPEAKER_03: So it gets me going.
• 16:41
  SPEAKER_03: I'm I'm gonna own it.
• 16:42
  SPEAKER_03: They can be very tall, very grand looking, right?
• 16:46
  SPEAKER_01: They're steep, they're often snow capped, you know, because they're really tall.
• 16:50
  SPEAKER_01: So they got some snow on the top, they're really beautiful, picturesque volcano.
• 16:54
  SPEAKER_01: I mean, if you're thinking you look up volcano image on Google, uh, that's what you're getting.
• 16:59
  SPEAKER_03: That's right.
• 16:59
  SPEAKER_03: That's right.
• 17:00
  SPEAKER_03: So these volcanoes, why do they look very different from shield volcanoes?
• 17:06
  SPEAKER_03: It has to do with the magma that makes them up.
• 17:08
  SPEAKER_03: Okay, shields are very runny magma, this basaltic kind of lava.
• 17:12
  SPEAKER_03: Strato volcanoes are made up of thicker, more viscous magma typically.
• 17:18
  SPEAKER_03: And uh the rocks that are associated with stratovolcanoes are usually andesite, which is intermediate in composition.
• 17:26
  SPEAKER_03: So it's not like rich in felsic or silica material, it's not deplete in silica material, it's kind of in between.
• 17:35
  SPEAKER_03: And what this does, this is so important because it forms then this magma that's stickier and thicker, and it's like a a thicker pancake batter.
• 17:45
  SPEAKER_01: So you make a thicker pancake batter and it can pile up a little bit more, and so you get these steeper sides to the volcano.
• 17:51
  SPEAKER_01: Although they look huge, you know, we look at them and think, wow, that's a massive volcano.
• 17:57
  SPEAKER_01: They're not they're not even close to the size of shield volcanoes typically in mass, in volume, because they don't have this really wide sides to them.
• 18:04
  SPEAKER_01: So sort of the amount of lava coming out of these individual volcanoes is smaller, much smaller than a shield volcano.
• 18:12
  SPEAKER_01: Even though they're very beautiful and picturesque and lots of magma can come out of them compared to shield volcanoes, they're smaller.
• 18:19
  SPEAKER_03: Yeah, they have a much lower supply of magma than shield volcanoes do.
• 18:23
  SPEAKER_03: And, you know, to that point, right, that stratovolcanoes they tend to erupt more violently, or at least they have the potential to do this.
• 18:32
  SPEAKER_03: And you know, basically, the more infrequent eruptions are with the volcano, the more violent it is.
• 18:38
  SPEAKER_03: And so shield volcanoes they erupt often.
• 18:41
  SPEAKER_03: You know, you talked about Fernandin and having this really recent lava flow, and Kilauea's doing that right now.
• 18:46
  SPEAKER_03: It's very active right now, been all over the news.
• 18:50
  SPEAKER_03: Because it erupts so frequently, it's non-violent, it's rather gentle.
• 18:54
  SPEAKER_03: And stratovolcanoes are the opposite, they erupt infrequently, and when they do, they tend to be more violent.
• 19:00
  SPEAKER_01: Yeah, I would say they're not quite the opposite.
• 19:01
  SPEAKER_01: They're like the intermediate again.
• 19:02
  SPEAKER_01: It goes to intermediate composition, they're intermediate in this eruption style.
• 19:06
  SPEAKER_01: So typically a stratovolcano will erupt a bunch of lava, it'll build itself up, and then every once in a while it'll blow itself apart, like Mount St.
• 19:14
  SPEAKER_01: Helens has.
• 19:15
  SPEAKER_01: It'll blow off the top of the volcano in a big eruption, and then it'll kind of build up with this, these smaller eruptions, these small sticky eruptions that build it up more, and then it'll blow itself up again and build up uh more and more and more.
• 19:27
  SPEAKER_01: And it repeats this cycle.
• 19:28
  SPEAKER_03: So it tends to alternate its eruptive style, right?
• 19:32
  SPEAKER_03: It's it's explosive in nature and violent in nature, and then once it's used up the gas in the chamber and the throat is clear, it tends to just erupt this the very thick lava.
• 19:46
  SPEAKER_01: So that right there, Chris, what you just said is sticks in my head from when you were teaching me this in class is the throat clearing analogy.
• 19:53
  SPEAKER_01: And that's exactly what's going on.
• 19:54
  SPEAKER_01: You sort of build up a big cough, and then you cough it out, and you really get that thing out, and then your throat is clear and you can sort of cough more and more.
• 20:03
  SPEAKER_01: I mean, you it's sort of the phlegm can come out a little bit easier, basically.
• 20:07
  SPEAKER_01: So that throat clearing analogy is a really great one because it basically coughs really hard and it gets that sticky plug out so the other lava can kind of flow behind it.
• 20:16
  SPEAKER_01: So we get this alternating sequence and it builds up in this alternating sequence of rock types.
• 20:21
  SPEAKER_03: And which is why it's called a stratovolcano, right?
• 20:24
  SPEAKER_03: It's it's kind of layered like this, where you get roughly equal amounts of lava flow coming out of the stuff, but it's a really thick lava that doesn't run laterally like a like a shield volcano will.
• 20:36
  SPEAKER_03: It just kind of forms this steep-sided dome instead.
• 20:39
  SPEAKER_03: Then it'll stop because the magma will get stuck in its own throat.
• 20:43
  SPEAKER_03: You know, it'll cool and it forms this kind of plug, right?
• 20:46
  SPEAKER_03: And so then it goes back to being quiet.
• 20:48
  SPEAKER_03: When it erupts again, it'll erupt explosively because it's gonna the this thick magma is gonna trap the gases.
• 20:54
  SPEAKER_03: And so then it'll erupt this ash and other pyroclastic material.
• 20:59
  SPEAKER_03: And so now you get this kind of alternating lava, ash, lava, ash, and that's why it's called a stratovolcano.
• 21:07
  SPEAKER_01: It's layered.
• 21:08
  SPEAKER_01: So these occur, Chris.
• 21:10
  SPEAKER_01: Where do these things occur?
• 21:11
  SPEAKER_01: Stratovolcanoes.
• 21:13
  SPEAKER_03: These are almost always subduction zone related.
• 21:17
  SPEAKER_03: And so you think of the West Coast, the northwest coast of the United States, you know, Northern California, Oregon, Washington, and so on, the the Cascade volcanoes, they are subduction-related volcanoes.
• 21:30
  SPEAKER_03: And you just this kind of this geology lends to creating a stickier type of magma.
• 21:38
  SPEAKER_01: That's right.
• 21:38
  SPEAKER_01: It happens all down the South American coastline as well, western South America.
• 21:43
  SPEAKER_01: It's all one big subduction zone.
• 21:45
  SPEAKER_01: The Andes are uh a series of volcanoes that are almost all these sort of stratovolcanoes.
• 21:50
  SPEAKER_01: Very common uh type here.
• 21:52
  SPEAKER_01: And you know, there's something interesting here.
• 22:00
  SPEAKER_03: That exists there.
• 22:01
  SPEAKER_03: And so that's why the rock is called andesite.
• 22:03
  SPEAKER_03: It's named after the mountains, the Andes mountains.
• 22:06
  SPEAKER_01: That's right.
• 22:06
  SPEAKER_01: And that rock type is actually a very, if we look at continental crust, the continental crust on average is andesite.
• 22:14
  SPEAKER_01: And so this is a very common way to make continental crust or to add new stuff to the continental crust in these subduction zones.
• 22:21
  SPEAKER_01: So a couple examples would be Mount St.
• 22:23
  SPEAKER_01: Helens, Mount Rainier, uh Cotopaxi, and Mount Fuji is probably another very famous one, or Fujisan.
• 22:30
  SPEAKER_01: These volcanoes that everybody, we kind of all can picture a stratovolcano.
• 22:35
  SPEAKER_01: It's what we think of when we think of a volcano.
• 22:38
  SPEAKER_03: Yeah, I'm in love with them.
• 22:40
  SPEAKER_03: I I spent a fair amount of my summer on them this summer, climbing Mount St.
• 22:45
  SPEAKER_03: Helens and Mount Shasta.
• 22:47
  SPEAKER_03: Mount Shasta's my favorite volcano.
• 22:49
  SPEAKER_03: I just, yeah.
• 22:50
  SPEAKER_01: You're uh stratovolcano obsessed, I think.
• 22:53
  SPEAKER_01: Would be fair to say.
• 22:55
  SPEAKER_03: You and I, you and I have banged around in uh on Mount St.
• 22:58
  SPEAKER_03: Mount St.
• 22:58
  SPEAKER_03: Helens.
• 22:59
  SPEAKER_01: That's right.
• 23:00
  SPEAKER_01: We talked about that last week in our Geo Short.
• 23:02
  SPEAKER_01: We uh we focused on Mount St.
• 23:03
  SPEAKER_01: Helens, and yeah, we had a we had some good times there.
• 23:05
  SPEAKER_01: That's right.
• 23:06
  SPEAKER_01: All right, next one, Chris.
• 23:07
  SPEAKER_01: Let's not get too hung up on stratovolcanoes here.
• 23:09
  SPEAKER_03: I'm sorry, I'm sorry.
• 23:10
  SPEAKER_03: All right.
• 23:10
  SPEAKER_03: Well, yeah, because you know, we're gonna jump into another type of volcano that I'm very much in love with as well.
• 23:16
  SPEAKER_03: These are the kinds of volcanoes.
• 23:17
  SPEAKER_03: Now we start to get a little bit more inclusive.
• 23:20
  SPEAKER_01: Those two previous types were two of the three that are typically taught in textbooks.
• 23:24
  SPEAKER_01: And now we're moving outside of the sort of typical three uh three categories here.
• 23:29
  SPEAKER_03: You know, hey, should we skip to cinder cones a second and just do that?
• 23:32
  SPEAKER_01: Yeah, let's do that to round off the first three.
• 23:35
  SPEAKER_03: Let's round off the three.
• 23:37
  SPEAKER_03: Um in fact, I don't even see it on my list.
• 23:39
  SPEAKER_01: No, you didn't put cinder cones on your list, you big dummy.
• 23:42
  SPEAKER_03: But we can that is really dumb.
• 23:44
  SPEAKER_01: Cinder cones are fairly small, typically.
• 23:47
  SPEAKER_01: They're rubby.
• 23:49
  SPEAKER_01: They look like they've got a whole bunch of rubble on the sides of them.
• 23:52
  SPEAKER_01: They you know they look like little pebbles, and they're they're sort of small volcanoes that kind of just spit out lava.
• 23:57
  SPEAKER_01: They spit out lava little small, sometimes violent, but short bursts of stuff.
• 24:02
  SPEAKER_01: They kind of spit lava into the air and then it falls down around the vent or around where the lava's coming out.
• 24:08
  SPEAKER_03: Which is why they're so steep-sided, because the stuff gets you know burped out of the volcano.
• 24:13
  SPEAKER_03: It often will cool in the air, this these lava fragments, you know, they'll cool in the air and they'll land as this kind of soft but mostly solidified rock at that point.
• 24:23
  SPEAKER_03: And so it's unconsolidated, it's not protected by lava flows.
• 24:27
  SPEAKER_01: It's hard to hike up because it's just boulders or pebbles of rock, you know, that erupted and cooled in the air.
• 24:33
  SPEAKER_01: And because that you know, that gets to the point of why do they look the way they look, is because there's it's not lava flowing, it's not liquid rock flowing along the surface.
• 24:41
  SPEAKER_01: It's actually stuff getting erupted in the air and then just cooling and falling down as rock for the most part.
• 24:47
  SPEAKER_01: Right.
• 24:47
  SPEAKER_03: Right.
• 24:48
  SPEAKER_03: And and so what are they made of?
• 24:50
  SPEAKER_03: Well, this is the thing.
• 24:52
  SPEAKER_03: Cinder cones don't fit nicely into a into a box either, because cinder cones can be made up of basically any kind of material, any kind of pyroclastic material.
• 25:01
  SPEAKER_03: They can be basaltic, they can be anacitic, they can be rhyolytic, very different compositionally.
• 25:07
  SPEAKER_03: And so you can't really fit them into a box.
• 25:10
  SPEAKER_01: They also occur everywhere for the most part.
• 25:13
  SPEAKER_01: They often occur as sort of, I think you said it earlier, parasitic uh volcanoes.
• 25:18
  SPEAKER_01: They're little volcanoes on the edges of bigger volcanoes, and so they occur in a lot of different tectonic settings on the shoulders of a lot of different other types of volcanoes as well.
• 25:27
  SPEAKER_03: Right.
• 25:28
  SPEAKER_03: So basically, wherever you have volcanism, you have the potential to have cinder cones as well.
• 25:33
  SPEAKER_01: They'll form relatively short periods of time.
• 25:35
  SPEAKER_01: It's just stuff getting chucked up into the air, coming down, they forms a pile that'll get wiped out by some big eruption later on, and then another little cinder cone will kind of form there uh again.
• 25:45
  SPEAKER_01: So um they're little baby, baby volcanoes that kind of get wiped out pretty quickly.
• 25:50
  SPEAKER_03: Some examples of these um craters of the moon in Idaho has some spectacular looking cinder cones.
• 25:57
  SPEAKER_03: They're awesome.
• 25:57
  SPEAKER_03: Cinder cones are beautiful.
• 25:59
  SPEAKER_03: I mean, because they're also very typical looking volcanoes with usually a well-developed crater at the top of it and so on that you can walk down into.
• 26:07
  SPEAKER_03: I mean, they're they're great.
• 26:08
  SPEAKER_03: I love these things.
• 26:09
  SPEAKER_01: Yep.
• 26:10
  SPEAKER_01: There's uh a few uh around the Grand Canyon in Arizona on the southern side of the Grand Canyon.
• 26:15
  SPEAKER_01: Southern side?
• 26:16
  SPEAKER_01: Yeah, southern side of the Grand Canyon.
• 26:17
  SPEAKER_01: Sunset crater is uh is one that people might have have gone to, but you kind of see them all over the place.
• 26:22
  SPEAKER_01: They're they're little Did you visit Sunset Crater when you were there?
• 26:25
  SPEAKER_01: We not recently, but I did uh in a field trip in college.
• 26:30
  SPEAKER_01: So yeah.
• 26:30
  SPEAKER_01: Yeah.
• 26:31
  SPEAKER_01: I mean they're beautiful, they're really stunning, and they make a really cool landscape.
• 26:33
  SPEAKER_01: They're like little cones sitting around, you know, that are small relatively small little features, but they're they're pretty.
• 26:40
  SPEAKER_01: They make for very pretty landscape.
• 26:41
  SPEAKER_03: Yeah, they are.
• 26:42
  SPEAKER_03: Uh, paracutine is another example in Mexico where this thing just started erupting in the 1940s.
• 26:47
  SPEAKER_03: I think it erupted for nine years or eight years, something like that.
• 26:50
  SPEAKER_03: Just in some farmer's field.
• 26:52
  SPEAKER_01: Yeah.
• 26:53
  SPEAKER_01: Oh, great.
• 26:54
  SPEAKER_01: I had the farm field, now I have a cinder cone in my yard.
• 26:56
  SPEAKER_03: I th that'd be my dream, actually.
• 26:58
  SPEAKER_01: That would be, wouldn't that be great?
• 26:59
  SPEAKER_01: I'm gonna have to move out of Michigan to get that.
• 27:01
  SPEAKER_03: But yeah, so now one other thing I want to say before we move on, just to jump back a second to their nature.
• 27:07
  SPEAKER_03: So they usually, when they begin erupting, because they have a lot of gas in the magma, they'll, you know, they kind of burp the stuff up and spatter the stuff up right.
• 27:15
  SPEAKER_03: And as the gas gets used up, sometimes the eruption can turn into a lava flow, then after this.
• 27:21
  SPEAKER_03: And and so you know, that's that's been fairly common um with their eruptive nature.
• 27:26
  SPEAKER_03: They're not hugely explosive because they're not big, they're not as big as stratovolcanoes, but they start rather violently, and then they as they use up the gas, they go back into being kind of this quiet, uh lava effusive kind of thing.
• 27:41
  SPEAKER_01: All right, let's move on now.
• 27:42
  SPEAKER_01: So, what do we got next, Chris?
• 27:44
  SPEAKER_01: And now we're moving outside of the classic three uh definitions.
• 27:48
  SPEAKER_03: Yeah, now we're gonna be more inclusive.
• 27:50
  SPEAKER_01: Yeah.
• 27:51
  SPEAKER_03: Um so we're gonna let's let's talk about rhyolite caldera complexes.
• 27:56
  SPEAKER_03: Okay.
• 27:57
  SPEAKER_03: Okay, which um I guess maybe in layman's terms, we're gonna talk about super volcanoes, then, right?
• 28:04
  SPEAKER_03: That's what these are often referred to as is rhyolite caldera complexes are super volcanoes.
• 28:09
  SPEAKER_01: And some people don't like the term super volcano, but these are big, big volcanoes, and they're big volcanoes that don't erupt much, but when they do, they go big.
• 28:17
  SPEAKER_01: They're the big, they're the go big or go home volcanoes.
• 28:20
  SPEAKER_03: Right.
• 28:20
  SPEAKER_03: So to keeping with the theme, right?
• 28:22
  SPEAKER_03: What do they look like?
• 28:23
  SPEAKER_03: Well, these are hard to recognize as volcanoes, right?
• 28:28
  SPEAKER_03: Because they're so freaking big.
• 28:30
  SPEAKER_01: They're so big, and it's not entirely clear that unless you look at the rock types, it's not entirely clear that there's a volcano there.
• 28:38
  SPEAKER_01: So it's definitely not what you think of, what you have in your head when you think of a volcano or when you Google a volcano.
• 28:44
  SPEAKER_01: This does not come up readily, right?
• 28:46
  SPEAKER_03: Yeah.
• 28:47
  SPEAKER_03: I mean, I don't know if if I you if I was alive a hundred years ago, standing in the middle of Yellowstone, I don't think I would know that.
• 28:55
  SPEAKER_03: Wow, I'm in a volcano.
• 28:57
  SPEAKER_02: Yes, right, right.
• 28:58
  SPEAKER_03: I just I don't know if I give myself enough credit, you know, or uh I just don't know if I'd recognize that it's so big you can't see.
• 29:05
  SPEAKER_01: Yeah, that's right.
• 29:05
  SPEAKER_01: And so well, the way they look is it's basically this huge, what's called a caldera.
• 29:10
  SPEAKER_01: It's this basically low area with some mountains on the edges or some small hills even on the edges.
• 29:16
  SPEAKER_01: And it's that way because they're not building up, the lava's not building up a volcano in the way that the previous volcanoes we've talked about, cinder cones, shield volcanoes, strato volcanoes, those are all lava building up this feature that we see.
• 29:29
  SPEAKER_01: A rhylite caldera complex is actually blows all the surface material out, and then it sinks down into that empty magma chamber.
• 29:39
  SPEAKER_01: So it empties this huge amount of magma out, blows up all the surface features, and then sinks down in.
• 29:45
  SPEAKER_01: So it's actually a depression, a big depression, instead of this thing that's been built up by volcanic eruptions.
• 29:50
  SPEAKER_03: Yeah.
• 29:50
  SPEAKER_03: Anything that would have been built up would be destroyed by these kinds of massive eruptions.
• 29:55
  SPEAKER_03: So it either, if it doesn't get destroyed, it gets swallowed in the caldera after the eruption in this evacuated magma chamber.
• 30:03
  SPEAKER_03: You know, it's just uh So Chris, why do they look this way?
• 30:08
  SPEAKER_03: Well, it's because of the type of magma that's involved, which is the theme that we've been you know hitting with this.
• 30:14
  SPEAKER_03: And so this is now the stickiest of the sticky in terms of lava magma.
• 30:19
  SPEAKER_03: Actually, pr to be precise, it's called magma.
• 30:22
  SPEAKER_03: So because it's not out yet, it's uh it's rhyolytic in nature, and rhyolite is an igneous rock that is uh extremely silica rich.
• 30:32
  SPEAKER_03: And so this is uh this stuff does not flow easily at all.
• 30:37
  SPEAKER_03: It's the thickest pancake batter you can imagine.
• 30:41
  SPEAKER_03: And if you pour this out uh onto a hot skillet, it's just gonna mound up.
• 30:47
  SPEAKER_01: You're gonna make a biscuit instead of a an actual pancake.
• 30:50
  SPEAKER_03: Exactly, exactly.
• 30:52
  SPEAKER_03: And so this kind of magma traps gases and it gets stuck beneath the surface.
• 30:59
  SPEAKER_03: And so it it erupts very, very infrequently.
• 31:03
  SPEAKER_03: In fact, no uh eruption of this nature has ever been witnessed by mankind.
• 31:10
  SPEAKER_01: Yeah, that's an interesting fact.
• 31:12
  SPEAKER_01: When was the la when was the most recent eruption of this kind?
• 31:16
  SPEAKER_03: Oh, it was 83 AD Taupo in New Zealand.
• 31:22
  SPEAKER_01: This is in New Zealand's on New Zealand's North Island, yeah.
• 31:25
  SPEAKER_03: I so 2,000 years ago.
• 31:28
  SPEAKER_01: But these are these are events when these things erupt, these are they're often referred to as super volcanoes because they affect all of the they can affect the globe, these things.
• 31:37
  SPEAKER_01: They can change climate for a little while.
• 31:40
  SPEAKER_01: These put so much volume of material into the air that they really do change the globe.
• 31:46
  SPEAKER_03: It's a game-changing event.
• 31:47
  SPEAKER_03: Yep.
• 31:47
  SPEAKER_01: Yeah, yep.
• 31:48
  SPEAKER_01: And so they occur in a couple different geologic settings.
• 31:51
  SPEAKER_01: They can occur in hot spots like Hawaii, except you can't have the hot spot underneath of the ocean or oceanic crust.
• 31:58
  SPEAKER_01: You got to put it underneath of a continent.
• 32:00
  SPEAKER_01: So Yellowstone is one example of this.
• 32:02
  SPEAKER_01: That's a hot spot sitting beneath a continent because you need to generate that really thick, gooey, sticky magma called rhyolitic magma, and that only happens beneath the continent or beneath a continent.
• 32:16
  SPEAKER_01: Um, these types of volcanoes can occur in subduction zones as well, and again, you gotta have the ability to generate this really thick, sticky stuff.
• 32:25
  SPEAKER_01: You gotta generate the stickiness to it so the throat gets clogged really, really aggressively, so it's gotta cough really, really hard to punch it out.
• 32:33
  SPEAKER_03: Yeah, yeah.
• 32:35
  SPEAKER_03: So examples Yellowstone, obviously, is an example of this kind of volcano.
• 32:40
  SPEAKER_03: Um, Toba in Indonesia is an example of this, and Taupo we just talked about in New Zealand, uh, are just these are three examples of them, and two of them are subduction related, and one of them is hot spot related.
• 32:53
  SPEAKER_03: Yellowstone's hotspot related.
• 32:55
  SPEAKER_01: So yes, that's right.
• 32:56
  SPEAKER_03: Yeah, they're awesome.
• 32:57
  SPEAKER_03: Okay, they're huge.
• 32:58
  SPEAKER_03: They're they're these are the things that change the planet when they go.
• 33:02
  SPEAKER_01: All right, next one monogenetic fuel, Chris.
• 33:05
  SPEAKER_01: Yeah, and these ones are weird.
• 33:06
  SPEAKER_01: Again, they're in the theme of they don't really look like volcanoes, they're hard to figure out that it's a volcano.
• 33:11
  SPEAKER_03: Yeah, they don't look like volcanoes at all, actually.
• 33:14
  SPEAKER_03: Um, okay.
• 33:16
  SPEAKER_03: In almost all of the volcanoes we've talked about, they have this plumbing system where the magma is has a path to the surface.
• 33:23
  SPEAKER_01: And the plumbing system we're talking about here is how the liquid, how the liquid rock gets up onto the surface.
• 33:28
  SPEAKER_01: So how its source is somewhere, it's formed somewhere deep down in the earth, various places, various depth, but it has to get out somehow.
• 33:36
  SPEAKER_01: And that plumbing system is this complicated network of paths that it uses to get out to the surface.
• 33:41
  SPEAKER_03: Right.
• 33:42
  SPEAKER_03: And in this case, these volcanoes, these monogenetic fields we call them, because we're not really gonna call them a volcano, because it's like this laterally big, huge area that has so many vents and pathways leading to the surface here that the lava has come out that it just leads to this.
• 34:02
  SPEAKER_03: I don't know how to describe it, like what do you say?
• 34:04
  SPEAKER_01: It leads to this kind of it's not one central volcano.
• 34:08
  SPEAKER_01: It's basically like making one huge pancake on the skillet.
• 34:12
  SPEAKER_01: You're sort of not pouring it from one bowl onto the skillet, you're pouring it from a bunch of different little places all onto the skillet, and it's it's really not a central vent or a central plumbing system that's bringing it out.
• 34:24
  SPEAKER_01: It's too disaggregated.
• 34:25
  SPEAKER_01: So it's kind of random stuff happening over the place, but it builds up actually a volcano or a volcanic field rather.
• 34:31
  SPEAKER_01: So monogenetic field has lots of little sources of magma that build up this kind of thick blanket of igneous rocks.
• 34:38
  SPEAKER_03: The supply of magma is so low in these situations, it doesn't allow for its plumbing system to like fully develop.
• 34:47
  SPEAKER_03: There's no clear path to the surface.
• 34:50
  SPEAKER_03: So each back batch of magma that comes out doesn't have this pre-existing pathway to the surface.
• 34:56
  SPEAKER_01: And a couple examples here are the San Francisco Volcanic Field and on the Seward Peninsula in Alaska.
• 35:02
  SPEAKER_03: All right, well, hey, let's talk about one that we've been to.
• 35:04
  SPEAKER_01: Yes, again, together.
• 35:06
  SPEAKER_01: And this might be my favorite type of volcano.
• 35:09
  SPEAKER_01: I I think I find these things fascinating, absolutely fascinating.
• 35:14
  SPEAKER_03: But they're certainly not my favorite.
• 35:15
  SPEAKER_03: You're nuts.
• 35:16
  SPEAKER_03: No way.
• 35:17
  SPEAKER_03: How can this beat out the cascades?
• 35:20
  SPEAKER_03: I don't know.
• 35:20
  SPEAKER_03: Like Okay, well, let's get into it.
• 35:22
  SPEAKER_03: Let's get into it.
• 35:23
  SPEAKER_01: Let's get into it here.
• 35:23
  SPEAKER_01: All right.
• 35:24
  SPEAKER_01: So we're talking about flood basalts, and there's no real flood basalts forming on Earth right now, so we don't have an active uh version of this really.
• 35:33
  SPEAKER_01: But what we have is a fossilized version of these, effectively fossilized volcanoes.
• 35:39
  SPEAKER_01: They're not fossilized in the way that we think of fossils forming, but it's an ancient volcanic eruption that we see the lava from.
• 35:47
  SPEAKER_01: We see the the rocks as a result of them.
• 35:50
  SPEAKER_03: Definitely.
• 35:51
  SPEAKER_03: So what kind of rock are they usually made of?
• 35:53
  SPEAKER_03: Well, first of all, okay, Jesse, what do they look like?
• 35:55
  SPEAKER_03: What do flood basalts look like?
• 35:57
  SPEAKER_01: These things are huge packages of basaltic rock.
• 36:01
  SPEAKER_01: They're layers upon layers upon layers of basaltic rock that are piled up on top of one another.
• 36:06
  SPEAKER_01: And you can see these things as discrete lava flows.
• 36:09
  SPEAKER_01: Sometimes the lava flows are so thick that they cool down and they crack in these sort of hexagons like Giants Causeway or like the Columbia River flood basalts, what we call columnar jointing in basalts.
• 36:20
  SPEAKER_01: So they form these really spectacular features in the way that they cool down.
• 36:25
  SPEAKER_03: I'm a huge fan of columnar joints, by the way.
• 36:28
  SPEAKER_01: They're totally cool.
• 36:29
  SPEAKER_01: Yeah, these like hexagons, right?
• 36:31
  SPEAKER_01: Of big, big columns of rock that are vertical, typically.
• 36:37
  SPEAKER_03: We saw some ones that weren't vertical, Chris, but because they form perpendicular to the cooling surface, and the cooling surface doesn't necessarily have to be it could the cooling surface can be cold rock, you know, and so you can get columnar joints that are not vertical.
• 36:52
  SPEAKER_03: Yeah.
• 36:52
  SPEAKER_01: But what do they look like?
• 36:53
  SPEAKER_01: They look like just a huge sequence of basalt that's sitting on top of one another.
• 36:58
  SPEAKER_03: And it's flow, it's a lava flow that cooled and hardened on top of flow, on top of flow, on top of flow.
• 37:05
  SPEAKER_03: So that's how they build up this kind of vertical mass of accumulation, which, like you said, you can often see.
• 37:12
  SPEAKER_03: They look like just really thick layers of sedimentary rock, but it's basalt usually, and it's you know, so it's not sediment, it's not layered that way, but it's a layer upon layer upon layer of basaltic lava flows.
• 37:24
  SPEAKER_01: Yes, that's right.
• 37:25
  SPEAKER_01: And the thing about these things and why they're called flood basalts, is you can think of this as lava flooding out onto the surface.
• 37:32
  SPEAKER_01: The volumes and the rate of lava erupting is absolutely massive.
• 37:38
  SPEAKER_01: We can put a ton of lava out onto the surface in a very, very short period of time.
• 37:43
  SPEAKER_01: And these things are different from our shield volcano style because of that rate of lava eruption, rate of extrusion of lava onto the surface.
• 37:53
  SPEAKER_01: They do enough eruption that there's a debate about whether when these flood basalts erupted, whether they changed the climate of the earth enough to, for instance, kill the dinosaurs or cause mass extinction events.
• 38:05
  SPEAKER_01: So that's to me how they're fascinating is because they're so big and so voluminous that they can really alter the climate of Earth enough to do things like cause an extinction event.
• 38:15
  SPEAKER_03: Well, okay, I feel like you need to explain that just a little bit here.
• 38:18
  SPEAKER_03: Like, how would these kinds of eruptions change the climate?
• 38:22
  SPEAKER_03: Just real quick.
• 38:23
  SPEAKER_01: So because they're putting so much, there's so much lava coming out on the surface, there's always gas associated with the lava.
• 38:29
  SPEAKER_01: And so because the volcano erupts gas as well, those volcanic gases can go up into the atmosphere and change the climatic conditions, either by putting a lot of sulfur dioxide in the atmosphere or a lot of carbon dioxide into the atmosphere, can really uh change the climatic conditions of the whole earth uh because they're putting they're doing that so rapidly.
• 38:49
  SPEAKER_03: Yeah, all right.
• 38:50
  SPEAKER_03: I I get it.
• 38:50
  SPEAKER_03: Now I um I take back a little bit what I said.
• 38:53
  SPEAKER_03: Okay, they're very they are really, really interesting.
• 38:56
  SPEAKER_03: I love them.
• 38:56
  SPEAKER_03: When I'm out in Oregon and Washington, um, you can't avoid these these massive flood basalts.
• 39:02
  SPEAKER_01: I find them really beautiful, you know, the uh Columbia River flowing through these big layers of basalt.
• 39:07
  SPEAKER_01: They're really pretty.
• 39:08
  SPEAKER_01: I I find I don't know, I find the the landscape kind of beautiful in a way.
• 39:12
  SPEAKER_01: Anyway, so that's how they form.
• 39:14
  SPEAKER_01: And it's not clear what drives their formation.
• 39:18
  SPEAKER_01: That we need a huge supply of magma, and they have to erupt really quickly.
• 39:22
  SPEAKER_01: So it's not your normal mantle plume, it could be some different model of a mantle plume.
• 39:27
  SPEAKER_01: We it's not um a super clear, it's not super clear how these things actually formed.
• 39:33
  SPEAKER_03: Just curious, uh, just popped into my head.
• 39:35
  SPEAKER_03: Have you you've not ever dated any of these rocks in the Columbia River basalts or no?
• 39:41
  SPEAKER_01: I have not.
• 39:42
  SPEAKER_01: I've got uh colleagues who work on this, and basically all they do is date, they they take rocks from the bottom of the lava flow, the middle, and the top, and then they determine the ages of when these rocks formed, and then they put together a time series of how rapidly these things um were erupted.
• 39:57
  SPEAKER_01: And it's it's really crazy how quick they go.
• 40:00
  SPEAKER_03: Okay.
• 40:01
  SPEAKER_03: All right, well, hey, let's talk about the next one then.
• 40:04
  SPEAKER_03: Mid-ocean ridge systems.
• 40:06
  SPEAKER_01: Mid-ocean ridge systems.
• 40:07
  SPEAKER_01: These are the underdogs, I would say.
• 40:09
  SPEAKER_01: The important ones that don't get any airspace.
• 40:12
  SPEAKER_03: Right.
• 40:12
  SPEAKER_03: And it's crazy to me, Jesse, when I think about this, how important mid-ocean ridge systems are in terms of like oars and and the you know, it's the biggest volcanic system that we have on the planet.
• 40:23
  SPEAKER_01: Yeah, and the reason they don't get any airwaves is because we rarely see them.
• 40:26
  SPEAKER_01: They're underneath the ocean almost all the time.
• 40:28
  SPEAKER_01: There's only one spot on earth where we actually see this kind of thing, and it's in Iceland, where the mid-ocean ridge system is exposed up on land where you can kind of walk around on it.
• 40:37
  SPEAKER_01: So, all right, Chris, they're really important.
• 40:39
  SPEAKER_01: I agree completely with you.
• 40:40
  SPEAKER_01: They're very important for mineral systems, they're important for climate, ocean chemistry, all this stuff.
• 40:45
  SPEAKER_01: What's going on here?
• 40:47
  SPEAKER_01: What do they look like?
• 40:49
  SPEAKER_03: Okay.
• 40:49
  SPEAKER_03: So to me, imagine a shield volcano.
• 40:54
  SPEAKER_03: Okay.
• 40:55
  SPEAKER_03: But it's not a circular shield, it is a linear shield, like an incredibly long.
• 41:04
  SPEAKER_03: Okay, but it's gentle sloping.
• 41:07
  SPEAKER_01: That's a great uh description right there.
• 41:09
  SPEAKER_01: It's not a point source, it's a line source.
• 41:11
  SPEAKER_03: It is a line source for sure.
• 41:14
  SPEAKER_03: So that's to me kind of what they look like.
• 41:16
  SPEAKER_03: They're very, very gentle, just like shield volcanoes are.
• 41:20
  SPEAKER_03: If you take your back to the batter and hot skillet, you take the batter and you just pour it on the uh across the entire skillet in a line.
• 41:30
  SPEAKER_03: And it's got to be runny batter, and that's gonna form what looks like a mid-ocean ridge system.
• 41:35
  SPEAKER_01: That's right.
• 41:36
  SPEAKER_01: And they look this way because there's a lot of magma, often, very often basaltic magma, coming up from the mantle.
• 41:43
  SPEAKER_01: And this is actually where new oceanic crust is forming.
• 41:46
  SPEAKER_01: So all oceanic crust is formed at base at a mid-ocean ridge system, and so the crust is pulling away there, there's lava coming up to fill that space, and it's actually forming new rocks and forming like seven kilometers thick oceanic crust with all new lava coming out, and so it's a lot of eruption going on.
• 42:06
  SPEAKER_01: A lot, a lot, a lot of eruption, and it's kind of as the name implies, in the middle of many oceans.
• 42:11
  SPEAKER_01: It runs right down the middle of the Atlantic Ocean in the Pacific, it's not right down the middle, but it's all around the edges.
• 42:16
  SPEAKER_01: And so, Chris, why do they look this way?
• 42:19
  SPEAKER_01: Like a shield volcano, I guess.
• 42:21
  SPEAKER_03: Well, because it's made up of basalt, and it's the same principle, it's very, very fluid, and so it tends to pour easily and and not mound up.
• 42:32
  SPEAKER_03: So you get this very gentle sloping volcanic feature.
• 42:36
  SPEAKER_01: And another part of the slope here is that as that new rock gets pulled away from the volcanic center, so it's a line that's always constantly being pulled away from the center of the line, it cools down.
• 42:48
  SPEAKER_01: And as it cools down, it gets denser, and so it sinks down a little bit too.
• 42:51
  SPEAKER_01: So we have that aspect going on a little bit as well.
• 42:54
  SPEAKER_01: And you know, we don't see these erupting a lot, so you know, their character is it varies a lot.
• 43:00
  SPEAKER_01: Some mid-ocean ridges are erupting a lot of lava very quickly, some are erupting less, uh, more slowly, and it varies here.
• 43:08
  SPEAKER_01: Uh, the speed of which the plates are separating kind of determines how much lava is coming up, basically.
• 43:14
  SPEAKER_01: So their character varies quite a bit, but they're more like shield volcanoes than like stratovolcanoes for the most part.
• 43:21
  SPEAKER_03: So to finish this part of it off, mid-ocean ridge systems, this is where new ocean floor is created.
• 43:28
  SPEAKER_03: This is where it all begins.
• 43:29
  SPEAKER_01: Yes, that's right.
• 43:30
  SPEAKER_01: Exactly.
• 43:31
  SPEAKER_01: So, all right, Chris, to kind of wrap up this thing, we went through a bunch of different volcanic types.
• 43:36
  SPEAKER_01: We went through the classic three shield volcanoes, stratovolcanoes, and cinder cones.
• 43:40
  SPEAKER_01: But those are not inclusive enough.
• 43:42
  SPEAKER_01: So we went through Rylite caldera complexes, the big ones.
• 43:46
  SPEAKER_01: We went through some monogenetic fields, flood basalts, my personal favorite, and the mid ocean ridge system.
• 43:52
  SPEAKER_01: But we've got one example here that we kind of want to highlight the complexity.
• 43:56
  SPEAKER_01: We want to drive home the point that all volcanoes are snowflakes and they're all kind of unique.
• 44:00
  SPEAKER_01: Geek here.
• 44:00
  SPEAKER_01: So let's discuss uh the Newberry volcanic complex.
• 44:03
  SPEAKER_01: And this is up in Oregon, right?
• 44:05
  SPEAKER_03: Yeah.
• 44:06
  SPEAKER_03: I've spent a lot of time around this area.
• 44:08
  SPEAKER_03: Um, and it is just I don't know how else to say it.
• 44:11
  SPEAKER_03: It's weird.
• 44:12
  SPEAKER_03: It doesn't fit into any of these categories.
• 44:16
  SPEAKER_03: You know, I don't know.
• 44:17
  SPEAKER_03: There are some varying ideas on what formed this thing.
• 44:21
  SPEAKER_03: Some say it's a hot spot, but actually, current research suggests that this is subduction related.
• 44:28
  SPEAKER_03: The same kind of the same subduction event that forms Mount St.
• 44:32
  SPEAKER_03: Helens and Mount Rainier and the Three Sisters and Oregon.
• 44:34
  SPEAKER_01: Yeah, it's kind of in that line of volcanoes, right?
• 44:37
  SPEAKER_01: It's sort of on the Cascadia line, a little bit off the axis, but mostly sort of associated with those types of volcanoes.
• 44:43
  SPEAKER_03: But it doesn't look like them.
• 44:44
  SPEAKER_01: Right.
• 44:45
  SPEAKER_03: At all.
• 44:46
  SPEAKER_01: Yeah.
• 44:46
  SPEAKER_01: So it looks kind of like a shield volcano.
• 44:48
  SPEAKER_01: It looks like what has been classified as some intermediate thing, a shield-shaped composite volcano.
• 44:54
  SPEAKER_01: So it's got this kind of blend, right?
• 44:56
  SPEAKER_03: Yeah.
• 44:57
  SPEAKER_03: It's so weird.
• 44:58
  SPEAKER_03: You can't nail down to what it looks like.
• 44:59
  SPEAKER_03: You can't nail down what it's made of.
• 45:01
  SPEAKER_03: I mean, it's made of basalt, it has andesite, it has rhyolite.
• 45:05
  SPEAKER_03: It's like it's very differentiated magma.
• 45:09
  SPEAKER_01: It's a very cool place.
• 45:12
  SPEAKER_01: So go check it out and go think about how weird volcanoes are and how unique they all are and how each one's different.
• 45:19
  SPEAKER_01: You got to go check them all out to figure it all out, right?
• 45:21
  SPEAKER_03: I actually think we should do a full episode on the Newberry complex in itself at some point.
• 45:27
  SPEAKER_01: Okay, well, that sounds good.
• 45:28
  SPEAKER_01: And the other one that is interesting in this space is actually one of the most famous composite cones out there, or one of the most famous stratovolcanoes out there, which is Mount Fuji or Fujisan.
• 45:40
  SPEAKER_01: And this is a weird one because it's actually mostly basalt.
• 45:44
  SPEAKER_01: It is erupted mostly basalt.
• 45:45
  SPEAKER_01: And usually stratovolcanoes are this andesitic composition.
• 45:49
  SPEAKER_01: So, you know, the one we think of when we think of stratovolcanoes doesn't really fit the classification scheme too well.
• 45:56
  SPEAKER_01: And there's some discussions about why it is so different.
• 46:00
  SPEAKER_01: Uh, it has a very voluminous eruption rate or a fast eruption rate.
• 46:04
  SPEAKER_01: So it's much faster, more lava's coming out per unit time than other volcanoes in that arc system.
• 46:10
  SPEAKER_01: And it's basalt, but it builds up this beautiful strato cone or strato volcano as well.
• 46:15
  SPEAKER_03: In fact, when we uh when we interviewed Dr.
• 46:18
  SPEAKER_03: Diana Roman, we said, What is your favorite looking volcano?
• 46:22
  SPEAKER_03: And she right away said Fujisang.
• 46:24
  SPEAKER_01: Yes, that's right.
• 46:25
  SPEAKER_01: It's like the perfect round symmetrical volcano.
• 46:28
  SPEAKER_01: It's amazing.
• 46:29
  SPEAKER_01: You know, one one last thing I want to kind of highlight here with these volcanoes is that I look at rocks and study the chemistry of the rocks that erupt out of some of these things.
• 46:38
  SPEAKER_03: Are you gonna go long here?
• 46:39
  SPEAKER_03: Or what are we gonna do?
• 46:40
  SPEAKER_03: No, I'll try.
• 46:41
  SPEAKER_03: Am I gonna take a nap right here right now?
• 46:43
  SPEAKER_01: Then is that yeah, you could probably you could probably leave.
• 46:45
  SPEAKER_01: Why don't you just take off and I'll I'll wrap it up here in the next hour?
• 46:49
  SPEAKER_01: No, I think you know, the plumbing system, we've been talking about the plumbing system a little bit of magma and how things get caught in the throat and all that stuff.
• 46:55
  SPEAKER_01: The plumbing system's really fascinating for volcanoes, and again, each one is unique and each one's different, but when we look at the rock types, each volcano at its central source has a different rock type.
• 47:07
  SPEAKER_01: But as you go away from that source, like you know, hundreds of feet or thousands of feet or a mile away from that source, still in the same volcanic area, the rock type changes a lot.
• 47:17
  SPEAKER_01: So we can get a lot of different rock types coming up in the same region or the same actually pretty close area on the Mount St.
• 47:23
  SPEAKER_01: Allen's volcano, lots of different rock types can kind of come up in different areas, and that makes some sense because the magma plumbing system is really complicated.
• 47:32
  SPEAKER_01: I mean, imagine your house plumbing system that looks pretty complicated.
• 47:35
  SPEAKER_01: A volcano is, you know, orders of magnitude more complicated than this, but actually the composition of the magma is different and the sources are actually different.
• 47:44
  SPEAKER_01: So actually, those plumbing systems can be very close together and they can go very, very deep and be totally separate pipes.
• 47:52
  SPEAKER_01: So we can get magma from different places very, very deep, if that makes sense.
• 47:57
  SPEAKER_03: I mean we talked about this in the Geo Short last week, yeah.
• 48:01
  SPEAKER_03: You know, with with Mount St.
• 48:02
  SPEAKER_03: Helens and how this is the thing, right?
• 48:04
  SPEAKER_03: I mean, it doesn't fit into these neat categories the way we teach it.
• 48:09
  SPEAKER_03: You know, even with Mount St.
• 48:10
  SPEAKER_03: Helens, you get this amazing diversity of rock there, which means you have this diversity and magma.
• 48:18
  SPEAKER_03: And uh it's just I it's awesome.
• 48:21
  SPEAKER_03: I love that stuff.
• 48:22
  SPEAKER_03: Like how how you know what did its path look like coming to the surface?
• 48:25
  SPEAKER_03: Did it come up and out fast?
• 48:28
  SPEAKER_03: Did it come up a little bit and then have a long residency, you know, in the crust, and then it's gonna change, you know, it's gonna diversify there.
• 48:36
  SPEAKER_03: And yeah, I love I love thinking through this kind of stuff.
• 48:41
  SPEAKER_01: Yeah, it's amazing to sit there and look at a volcano.
• 48:44
  SPEAKER_01: You look at Yellowstone as soon as you realize it's a volcano, or look at Mount St.
• 48:48
  SPEAKER_01: Helens, or look at you know, the loss in volcanic field or any of these things, and think, how did that form?
• 48:55
  SPEAKER_01: That's really a fun exercise.
• 48:57
  SPEAKER_01: Very, very cool.
• 48:59
  SPEAKER_03: Even with um Yellowstone, you have rhyolite of of course, you have basalt, which is confusing, right?
• 49:05
  SPEAKER_03: And you have a lot of obsidian all in inside of this caldera, you know, very, very cool stuff.
• 49:13
  SPEAKER_01: All right, Chris.
• 49:14
  SPEAKER_01: I think that's probably a wrap, right?
• 49:17
  SPEAKER_01: The classifications of volcanoes.
• 49:19
  SPEAKER_01: It's complicated.
• 49:20
  SPEAKER_01: Each one's a snowflake.
• 49:21
  SPEAKER_01: That's right, that's right.
• 49:23
  SPEAKER_01: All right.
• 49:23
  SPEAKER_01: Well, you can find us at Planet Geocast on all the social medias and um give us a like, a subscribe, leave us a review, those really help, those really matter, and uh tune in next week.
• 49:36
  SPEAKER_03: Yeah, have the best week.
• 49:38
  SPEAKER_01: All right, see you, Chris.
• 49:39
  SPEAKER_03: Yep.