Are You Karsty? Sinkholes
Dr. Jesse Reimink: [00:00:00] Welcome to Planet the podcast where we talk about our amazing planet, how it works, and why it matters to you. you have the majority of difficulties. So let's just say that.
am recording.
Chris Bolhuis: Finally, thank you for, for coming online, Jesse. Like, my gosh, this is, uh, not been your morning, has it?
Dr. Jesse Reimink: Chris, every morning is my morning. What are you talking about?
Chris Bolhuis: You always give [00:00:30] me crap about being old and having technological difficulties, but you have the majority of the
Dr. Jesse Reimink: Here's the thing, Chris. I now have a trump card that I can play whenever the heck I want. And it's the fact that you ran out of Google storage space and deleted all of your emails. That is just, you can never criticize anybody about technology ever again.
I think you've lost that right.
Chris Bolhuis: It made sense to me. I'm like, Oh my gosh, I have 15, 000 cent emails that are just sitting there. I need to get rid of them. And then I [00:01:00] needed them.
Dr. Jesse Reimink: Emails are so valuable sometimes, you gotta go back a
Chris Bolhuis: Well, I
Dr. Jesse Reimink: you're, I see, it's gonna come a point where we're gonna get into a disagreement about something that happened in the past, and you're gonna want to go back and look up an email to see what happened in an exchange between you and I, and you're not gonna have any data, and I'm gonna win the argument, because I have it, and, and you're gonna lose because of that.
Chris Bolhuis: Here's what comes to my mind. You restructured all of our stuff in our shared Google drive for this, this, you know, this thing that we do, and you'd lost [00:01:30] all of our scripts and you know how many times I've wanted to go back
Dr. Jesse Reimink: Oh, oh, whoa, whoa, whoa, one season, season one of Scripps was the only one that got overwritten.
Chris Bolhuis: Well, that's a third. Jesse, that is 33 percent of what we've done that's just
Dr. Jesse Reimink: Yeah, Chris, you know what? Here's the thing, Chris. We're all about new stuff here at Planet Geo. We are all about new stuff. We don't go back and revisit the past that much. No, that's not true. We're talking about geology. That is completely wrong. I take it back. We're talking about geology. It's all in the past.
Chris Bolhuis: you know what I think? I think you just need to [00:02:00] start being nicer to me and I think other people agree.
Dr. Jesse Reimink: We, there has been, let's see, how do we phrase this? There have been a couple, uh, emails, reviews, comments that seem to suggest, I think people are a little defensive of you, Chris. People are on your side. They don't like the way I treat you. And how do you feel about that?
Chris Bolhuis: I think you need to do better to be honest with you. I,
Dr. Jesse Reimink: I'm too mean. I mean, I know that Joyce thinks that I'm too mean to you, but.
Chris Bolhuis: yes, she does not refer to you as the good doctor anymore. [00:02:30] Did you know that?
Dr. Jesse Reimink: no, I'm the bad doctor now. And what
Chris Bolhuis: know, the, you just, I don't know, she just stopped saying doctor now, she just calls you Jesse, she doesn't refer to, she doesn't give you the title
Dr. Jesse Reimink: I've lost some respect in the, from the Bolhuis household. Wow. Interesting. Okay. I really got to, I got to tighten up around here, I guess. Okay,
Chris Bolhuis: I think so. Oh, Hey, there's another funny thing too, but I'm going to tell you this. This just popped into my head. one of my students said, Mr. Bolhuis, I found your podcast and we've been listening to it. And that, cause this [00:03:00] family travels quite a bit, you know, so they'll go on big road trips and so on.
And he said, so we listened to it when we're on these road trips. And I said, well, hold on though, but you do understand, right? There's some swearing in it. And he's like, Oh yeah, yeah, I know that. But that's usually, Jesse that does the swearing. And
Dr. Jesse Reimink: Wow. I want it. We need to go back through our, our, our transcripts here. I, is that true? Maybe it is true. I don't know.
Chris Bolhuis: happened. This was, I think this was just two days ago that he brought the, and we haven't talked
Dr. Jesse Reimink: Wow. You know what? I'm [00:03:30] starting to get a reputation here. What the heck? Okay, here's what I need. If you're listening to this and you're on Team Jesse and not team Chris, you
Chris Bolhuis: Oh,
Dr. Jesse Reimink: an email
Chris Bolhuis: do this. We do not need to be pitting people up against you and I,
Dr. Jesse Reimink: I know, I know.
Chris Bolhuis: like you and I are really, really good friends and we like to rip on each other and that's just the way it
Dr. Jesse Reimink: That's just the way it is. That's right. It's all with love. That's exactly right. so today, Chris, this is a. This is a little bit of a follow on from our Disappearing Streams episode, because we talked about Disappearing Streams, we talked about how, [00:04:00] you we came about it from two very different sort of mindsets or different categorization schema what a Disappearing Stream was, but as part of that, we really focused in on Karst, and I think we didn't do a good job Great job of really nailing the definition of karst.
And so karst is K A R S T. That's the word we're saying, karst. And that is a, uh, sort of a type of really topography that's controlled by the underlying geology. And part of karst [00:04:30] is sinkholes. At least that's what I always think of when somebody mentions karst to me. Immediately, my mind goes to sinkholes.
And I talked about how I live in Pennsylvania in this karst area. And we just had a sinkhole open up on campus, like right near a big parking deck. uh, that was a little while ago now, but know sinkholes happen. Sinkholes are not an uncommon thing in the state college, the central Pennsylvania.
area. and so this is kind of a little bit of a follow on episode to describing that aspect.
Chris Bolhuis: that's right. when I think of [00:05:00] karst versus sinkholes, I think of sinkholes as more singular. where you can have something happens and, it collapses down in and of itself. And we're going to talk about the different ways that this can happen as we progress through this episode.
And I think of Karst as more of a, this is not singular, it's more, The topography is dominated by many, many, many sinkholes. That's how I think of karst versus
Dr. Jesse Reimink: And you're exactly right, Chris. that is the, the aspect of karst that, sinkholes is one part [00:05:30] of a karst topography. You can have caves, you can have disappearing streams. All of those go together in the, the karst bin. the features that define karst topography are sinkholes, caves, disappearing streams, lots of groundwater, surface water interaction.
Chris Bolhuis: Okay. So Jesse, the premise of this whole thing that we do here, this Planet Geo podcast is why geoscience should matter. to everyone else. So I'm going to throw this out at you. Why are we talking about sinkholes then? If this is [00:06:00] something that matters, it has societal relevance. you need to support that.
I think you gotta, you gotta sell that to our listeners
Dr. Jesse Reimink: So, uh, this is an interesting aspect of, and that one of the main benefits have gained from doing this podcast with you is not only that we get to hang out more, which is great, and very fun, but also I sort of pay attention to different stuff than I used to before we started doing this podcast. So, we talked about karst and disappearing streams, couple of weeks ago now, there was an, an article in the AGU sort of [00:06:30] Publicationsphere in the EOS
Chris Bolhuis: The American Geophysical Union. That's what AGU
Dr. Jesse Reimink: yeah, so this is a, you know, geoscientists, um, in the, in the US that they published an article on a research article.
And basically this was a publication that made a map of sinkhole susceptibility across the United States. So I clicked on this. I would have not clicked on this three years ago. Definitely would not have. I would have been like, Oh, whatever.
Chris Bolhuis: That is such a good point, Jesse. And so true. I also view the world [00:07:00] around me very differently because we do this podcast together. I don't know. It's a, that's such a good point. I guess I never really deliberately or consciously thought about that, but when you said it. I automatically thought, that is so true.
I look at everything differently. It's kind of like when I was brewing a lot of beer, you know, I got really good at it, and I
Dr. Jesse Reimink: You got really good at it. There was a strawberry wheat beer that you made for a while. Strawberry wheat, right? Is that right? Yeah, strawberry [00:07:30] wheat. Or cherry wheat.
Chris Bolhuis: Cherry wheat, strawberry wheat. I made it all because I couldn't look at anything. Jesse, I was looking at everything, thinking to myself, I wonder if I can ferment that, like, seriously.
So I'd go through the grocery store and I'd be like, I can ferment that. I know I can, and then I would just play around with it. so I haven't brewed hardly anything since we started doing this podcast, because I just don't have time. And this chews up, this takes up really a lot of [00:08:00] time to do.
So I've transitioned now to thinking about the geologic world Completely differently, but it's like I used to work view the brewing world. You know, I could just affected my whole
Dr. Jesse Reimink: Yeah, just the total outlook. And so I click on things because I feel strongly and you, we've talked about this, we were just talking about this before we hit record, what is the societal relevance? Like, you know, that is a big component of what we're trying to do here.
And so. you and I both feel we have to defend that statement a lot, right? And so if there's any press article [00:08:30] or news article or new thing that sort of is in that space where, Hey, somebody did something interesting in geoscience and here's why it matters. I'm going to click on that in a way that I really didn't before.
I was super interested in just, you know, igneous petrology. and, uh, so it's a really interesting exercise. Anyway, to come back to
Chris Bolhuis: Hold on. Hold on. I'm gonna interrupt you a second Jesse because in a previous episode, you asked me about how I approach my students in terms of relevance in what you teach.
Right. Cause especially with [00:09:00] my freshmen, these 14, 15 year old kids, they're taking an earth science class where we study the planet and how it works and why it should matter to them. Right. And, You asked if I do that differently now because of things that we've done on this podcast and the series about critical elements and rare earth elements and all these things.
so. just this past week then, I began to talk about rocks and the rock cycle, and I'm using that as a launching pad to talk about our resources then, because I think you have to do it in [00:09:30] that order, right? You can't talk about resources before you've talked about minerals, rocks, and the rock cycle, right?
It just, that has to be the pedagogy. So, I pick out four rocks that I think are just, I take them off my shelves, you know, and I think they're awesome and I tell them the story of these rocks, you know, how they formed and, and what they mean and the process of discovery that went into telling this story,
Dr. Jesse Reimink: Let me interrupt you real quick and just paint a visual because, you know, Chris, the Chris Bolhuis [00:10:00] classroom, at least the old classroom used to be, and I think you still have this, is this beautiful, like, bookshelves, like big glass door, floor to ceiling bookshelves with rocks in them, Full of rocks.
I mean, you have an impressive rock collection there and mineral collection as well, and so you're pulling these things out, handing them around and describing, I mean, that's just the visual hearing classes it was to the right of the students sitting in your old classroom when I was taking your class, it was that big bookshelf all to the right.
I mean, basically the entire sort of square classroom, the right side was [00:10:30] all rocks in these floor to ceiling bookshelves with, glass panes. So you could see into them. It was beautiful.
Chris Bolhuis: So in my new classroom, we moved in 2014 into this new building and they, they custom designed just for me. I'm the only science teacher that has these. It's the same thing. Floor to ceiling, glass shelved, glass doors, It encases my entire lab area. So I have a classroom area and a lab area. And so it's, it's a little bit of a different setup, but it is, it's [00:11:00] spectacular.
So you're right. That's exactly, I pulled out of there. I just picked four rocks and I talked about them. but at the end, I said, listen, this is, this is the story of these rocks, and this is why I'm so passionate about what I teach because these stories are pretty cool. And the kids, they agreed, like, yeah, that's pretty awesome, Mr.
Bolhuis. but in addition to that, I talked about things that I probably wouldn't have talked about if it weren't for this podcast. I talked about the rare earth elements, the importance of lithium and the importance of copper and vanadium, [00:11:30] these things that we're talking now about things that weren't even on people's tongues 10 years ago.
Dr. Jesse Reimink: I know it's, it's just such a different world where we're sort of living in. And I think you and I are gaining exposure to that, through doing this podcast. I mean, we kind of are, we, we sort of have to pay attention to a different, a different and growing and important cross section of our field that maybe we, we didn't pay as much attention to.
I, I'd love to have a longer conversation about this, about how this like brave new world that I think is [00:12:00] happening right now. How do we incorporate that into the classrooms better? I think it'd be really interesting conversation to have with you and I have certainly, and maybe, somebody else to bring on who can help talk about this, because I've certainly done it and continue to do it differently throughout the semester this year than I did last year and the year before that as well, because as you said, real quick, last tangent, and then we'll get to sink holes in cars is because the story's in the rocks.
That's what we're kind of talking about. This, the story is in the rocks here, but. as you said, you have to talk about the rock cycle and minerals and [00:12:30] plate tectonics before you can start to talk about the societally relevant aspects here because otherwise it's just going to not going to make any sense, right?
Like if you're talking about lithium pegmatites, you got to understand a little bit about igneous petrology to get to that point. So in the, you know, the normal structure of a class and a textbook too, is all of this like societally relevant, interesting stuff gets put in the back, like the last couple of chapters, because you have to have all the basics, the basic framework in place before you start to talk about lithium pegmatites.
Right. and I always [00:13:00] did, I never got there. The last like four years I've taught this intro to geology class. rarely like get to it. Cause I. I take too long to get to the end of the semester. So by the end of the semester hits, like, I'm like, okay, glaciers, we're, we're going to end on glaciers this year.
We're not getting to the like interesting stuff, but this year I decided I'm going to sort of, you know, spin copper, take one of them that's important and try and tell the story in pieces as we go along. So I started telling this, you know, in the house solar system formed and what copper is in there.
Anyway, I'm [00:13:30] trying to like weave it into the story more, but I don't know that that's right. educationally,
Chris Bolhuis: absolutely think it's right. I think you actually need to move your discussion about resources to the front end of your curriculum.
Dr. Jesse Reimink: totally about why they matter. and
Chris Bolhuis: around.
Dr. Jesse Reimink: the knowledge base on that for sure. For sure.
Chris Bolhuis: Um, I kind of frame it with my kids. I was just talking about this and, and again, then we'll get to sinkholes, but, it's kind of like knowing where your food comes from.
I think that that's important, and the same applies to resources. We need to know where these things come from.
Dr. Jesse Reimink: [00:14:00] your iPhone come from? You know, where does your, where does your computer come from? It's super important. I totally agree. And it's something that we as geologists and geoscientists have not done a good job on for the last, 20 years, and it's super important that we do right now.
I mean, now is the time. it is clearly important, it's a brave new world, as far as, like, the implications of geoscience, and we have to do a better job of it. So, with that segue, do I get the segue word? No, not quite. But, with that segue, sinkholes. Okay, [00:14:30] here's the, here's, like, one statistic of, of many that we could use, but, there's been these resource
Chris Bolhuis: Hold on, hold on. got to stop you just for a second, because I, it's been a long time since I asked the original question.
Dr. Jesse Reimink: That's a good point. Wow. That was a quite a tangent. We went on there, Chris. I mean, geez.
Chris Bolhuis: I know, but that's okay. It's our podcast and we can do what we want. Why are sinkholes relevant to society?
Dr. Jesse Reimink: Okay. So here's just a couple numbers for this. And again, we're going to be a little us centric here. cause that's where we live. And again, [00:15:00] it's our podcast, in 1997, FEMA, the Federal Emergency Management Agency, we've all heard of FEMA, I think, but, suggested, or there's been this number that's put out there, that in the U. S., sinkhole losses, so sort of economic losses due to sinkholes, was on the order of like 125 million per year, or Some other estimates by the USGS around that time, late nineties was like 300 million a year.
So that's kind of been the number that people use, which is a big number, right? that surprised me that number, but the USGS in this recent publication just calculated that [00:15:30] Florida alone had nearly 1. 5 billion in losses due to sinkholes just in the last five years. So Florida alone over five years was.
getting a yearly rate higher than that. So like it matters and I think it's kind of a representation that we don't quite know how much it matters. How, important are sinkholes? They're clearly those are big numbers but how important kind of are they. And so we're gonna sorta, sorta structure this conversation about the geology of sinkholes, a little bit around a recent, sort of, map that was made by USGS [00:16:00] geologists that, tried to quantify this or predict this a little bit better and produced what's called a sinkhole susceptibility index across the US and sort of say, okay, where's it important to pay attention to sinkholes?
Chris Bolhuis: That's right, brings up the point that Every one of the 48 contiguous states, plus Washington, D. C., have areas that are likely for sinkhole development.
Dr. Jesse Reimink: which that, think it just intuitively surprised me. Because again, I think sinkholes, I think karst, and you think [00:16:30] karst, you think those of you that are geologists will think, you know, Tennessee, Kentucky, Pennsylvania, places where there's a lot of carbonate rocks, a lot of rain, karsty areas, places where there's caves, right?
where are there caves? Okay, that's where sinkholes are probably forming.
Chris Bolhuis: Did you just invent a word right there? You just said karstie.
Dr. Jesse Reimink: Karstie. Yeah, that's a good one, right?
Chris Bolhuis: I like it. It is. I knew what you meant,
Dr. Jesse Reimink: a good one. Chris, are you Karstie? Are you Karstie, Chris? And the good news is, we could sell t shirts in all of the lower 48 states. Because everybody's Karstie.[00:17:00]
Chris Bolhuis: I'm not karstie. I might be krusty, but you know,
Dr. Jesse Reimink: So Chris, I, they're kind of every, or these sinkholes are everywhere, but how, I think it, let's talk about how sinkholes operate and what forms them. So how do sinkholes form?
Chris Bolhuis: I can do that because you said these, what three or four states you listed off, you said Kentucky and Tennessee and Florida and even Missouri because of these carbonate rocks. And, and those are typical karst [00:17:30] formations, right? There's another kind of karst that's called pseudokarst. So we have, we have these like traditional, where you have rocks that are getting dissolved, if you think about this, then if you have like, let's say limestone, subsurface limestone and groundwater that's slightly acidic is flowing through this.
It's selectively dissolving the limestone, opening up cavities, and over time, these cavities can get big enough where collapse happens, especially if they're [00:18:00] really near the surface, right? Then it's easy for collapse to
Dr. Jesse Reimink: Oh, that's a good point, Chris. Let me just, sort of double click on this or frame this a minute. Karst is a topography type, so has features like caves, sinkholes, disappearing streams. We're talking about sinkholes specifically, how sinkholes form, and you're pointing out that there's There's karst and there's pseudokarst, and those are like a, a topography type or a category, but sinkholes are one component of those things.
And there's multiple ways that sinkholes can form. So sorry to interrupt there. I just wanted to make sure we were kind of on [00:18:30] the same high level page there of what this are. So karst is dissolving rocks, like you said, right? It's dissolving carbonate. And water is very good at dissolving things like marble or calcite or limestone or dolostone.
We talked about that in a previous episode. Water is really great at dissolving those things.
Chris Bolhuis: That's right. And there are two kinds of karst or sinkhole formation. One is called suffosian, or it's this kind of gradual [00:19:00] subsidence sinkhole, or as you probably would call it, you'd probably call it subsidence because you
Dr. Jesse Reimink: yeah, that's right. You gotta
Chris Bolhuis: Yeah,
Dr. Jesse Reimink: gotta take
Chris Bolhuis: aware
Dr. Jesse Reimink: to be fancy.
Chris Bolhuis: that's right.
And, this kind of sinkhole formation is, is not dramatic. It's not very sexy at all because it's, it's just this kind of slow process. Whereas water trickles down, it carries not only the water with it, but sediment with it. and it can form this kind of gradual, slow, monotonous, it's kind of like soil creep, if you will.
It's,[00:19:30]
Dr. Jesse Reimink: Chris. It's, it's slow and it, you know, you worry about it, you got to know if it's going to happen when you're like building a building, you don't want to build your building there, but it's not like going to, it's not going to kill you, you're not going to fall into it because it's super slow and it's kind of this bowl shaped depression, I suppose.
So that's number one type of sinkhole.
Chris Bolhuis: And the other one is much more dramatic. This is a sudden collapse sinkhole. And this, this can be deadly. It can be, it's kind of a violent sort of event, right? Where it happens catastrophically. and it's the most damaging kind. It's the most concerning kind. [00:20:00] And geologically it's the coolest kind also.
Dr. Jesse Reimink: Yeah, right, It's
Chris Bolhuis: it, it can be, yeah, very fascinating.
Dr. Jesse Reimink: So the way to think about that, cover collapse one is basically you have like a rigid roof over your cave and the roof of the cave collapses, which, you know, obviously if you're standing on the surface, when that thing collapses, you're, you're going to fall into the cave, right?
that's kind of the idea. It's rapid it can be really traumatic, You think of immediately happening, but it can happen over the course of a couple of days and it's slumping and the whole thing is kind of falling in. And that would still be a cover [00:20:30] collapse sinkhole It is falling into a void. the ground is falling into a cavity, an open cavity that used to be stable and is not now.
Chris Bolhuis: And, this brings up kind of a side tangent, so give me a little bit of leeway here. one of my favorite rocks is Breccia,
Dr. Jesse Reimink: Hey, look at how nice I'm being to you. I'm giving you leeway
Chris Bolhuis: I know, that was, that was very polite.
Thanks. Thank you. Yeah, one of my favorite rocks is a rock called Breccia, and it's B R E C C I A, so it's a very [00:21:00] mispronounced word. A lot of my students will call it Breccia, and I'm like, no, it's like you Breccia, you know, with a chuh, I love this rock because it's, it's a lot like conglomerates.
It's made up of large... high energy clasts. But breccia is different from conglomerate in that it's made up of angular clasts. And to any budding geologist, you quickly learn that angularity, when you're talking about pieces that are in a rock, means that it hasn't been transported very much or very far.
It's high energy because they're large. But they're [00:21:30] angular and sharp and jagged. And so they haven't, they formed very quickly without a lot of transport, right? so up in the upper peninsula, there is limestone near the surface that has collapsed and it forms this kind of collapsed breccia. Does that make
Dr. Jesse Reimink: yeah yeah yeah, this is really, okay. it's a beautiful rock. I remember we saw one of these, I'm not sure if this is, I, I, I seem to remember, this is going back to my undergrad days, but I saw one of these in a, um, a field trip in Death Valley, in the United States, where there's this [00:22:00] mega breccia, which, the blocks, the pieces of breccia, the angular blocks of rock are like the size of a car, and it's cemented with Calcite.
And so what fills in the gap is calcite, calcium carbonate. And, I seem to remember there being a bit of a debate about how this megabreccia in the, in death Valley actually formed, but this is one good way to form it is imagine this is a great point, Chris. This is a super cool rock.
And imagine you have a roof of a cave that collapses down in the roof. Pieces of rock are going to be angular, [00:22:30] they're going to fall into a big pile at the bottom of the cave, and then what do you have in caves, you have stalactites and stalagmites forming, you're having water that is enriched in calcite, basically, through there and precipitating calcite in between the rocks, and then it's kind of melding them together in a way, and forming this beautiful breccia.
the way that this rock in the UP was formed?
Chris Bolhuis: It is exactly how this rock in the UP formed. So it's called the Collapsed Breccia.
Dr. Jesse Reimink: breccia, okay, yeah,
Chris Bolhuis: And what I love about it is that the story is so[00:23:00] well laid out. You can hold the rock in your hand and you can just see how this, how this formed, especially, if you're on site, right? You're at the outcrop.
You can see the outline of the cave that the rock collapsed into. What I love about Breccia is the story that it tells, right? It comes back to, it always comes, for me, it always comes back to that. So anyway, let's get back on track. you gave me some leeway, so.
Dr. Jesse Reimink: I like it. That's a, I mean, it's a beautiful rock. I don't think I've seen the one in the UP you're talking about,
I have, Oh, we saw it on the field trip. Okay. I don't, uh, I was too obsessed with [00:23:30] the veins and the, and the, you know, on the shore of Lake Michigan and cross cutting relationships to figure that one out.
But, these things are really pretty rocks. Cause they get cemented with calcite. And so you have this sort of white, Cement, that's, bonding them together, but one important thing about karst. So, okay, sinkholes are one part of what we call karst topography. Karst topography, again, is formed in areas where There is dissolvable rock. So there's rock being dissolved. What is creating these cavities underneath of the ground, we've really hit on that [00:24:00] point. So that's what karst is. And it's an important statistic here that around 20 percent of the U S is underlain by karst landscapes, which is way more than I would have guessed.
that's a lot, right? It's almost like a fifth of the U S is underlain by karst.
Chris Bolhuis: Question for you. Does that stat include all karst? Does it include pseudokarst as well, which we'll get into here in just a
Dr. Jesse Reimink: No, I don't think so. that is just karst, like, dissolvable rock underneath there. And 40%, another mind blowing stat, [00:24:30] 40 percent of the groundwater used for drinking in the U. S., comes from karst aquifers. That blew me away. That is so much. 40 percent is a lot. okay, so that's karst. Dissolvable rock, you get sinkholes, you get caves, you get disappearing streams. What is pseudokarst? geologists are not great at naming things in a really creative way, so
Chris Bolhuis: Oh, I actually like it.
Dr. Jesse Reimink: I mean, it's a cool name, but it's... It's a little confusing.
Chris Bolhuis: I dunno, I like it. I mean, you're a little pseudo intellectual, so, you know,[00:25:00]
Dr. Jesse Reimink: That, well done, that was a good one. That was quite good, Christopher. Well done, Christopher.
Chris Bolhuis: it.
Dr. Jesse Reimink: you're uh, you're in fuego today. Nicely done.
Chris Bolhuis: Thank you. Thank you. Pseudo means false. And so this is a different kind of karst. Let me, I think the best way to explain this is just by going over some examples of it. pseudo karst can be, let's say volcanic caves. which are usually lava tubes, right? if you can, let me just go through this a second real quick, but if you can [00:25:30] imagine a very thick lava flow, let's say a thick lava flow, that comes out of a vent of a volcano.
And what happens then is the surface, the part of the lava that's in contact with the air cools the fastest, right? That just intuitively makes sense. It cools from the outside in. Well, what you're left with then with this really thick lava flow is the The central part of that lava flow is insulated by all of the rock that's already solidified.
And so it stays molten much, much longer. [00:26:00] It's not going to cool. It's kind of like putting hot water into a thermos versus just an open mug. it's going to stay hotter longer. Right. So. What the the lava then will flow through this insulated tube and eventually it gets to the edge of the lava flow where the lava just kind of comes up and out and what this does is it allows these kinds of volcanoes to sprawl laterally, right?
I always think of like Hawaiian type eruptions,
Dr. Jesse Reimink: hey Chris, let me interrupt real quick, because the, you know, I think people might have seen these [00:26:30] videos when, when, Kilauea or something is erupting, you'll see the volcanic center's at the, the middle of the island, but you'll see these videos of lava dumping into the ocean.
And that's because lava tubes are transporting that stuff just slightly underneath the surface in a molten form all the way out to the flanks of the volcano, which are out on the, uh, you know, out on the coast, basically. So, lava can go a long, long ways in these lava tubes. A long
Chris Bolhuis: I think, Jesse, didn't I take you [00:27:00] to, into a lava tube
Dr. Jesse Reimink: You did. Yes, you did. And we did. And, uh, I was, I just went back to that, that same one, uh, last year, two years ago on our field course, our Penn State, uh, field course goes out there and we were wandering around the exact same ones. And actually, This is how you get pseudocarsed because the lava tube, it's not that hard to imagine.
The lava tube has a thin roof on it. Couple feet, couple meters, and that can collapse. And actually the way you get down into this lava tube, at least at Craters of the Moon National Monument is you [00:27:30] climb down one of these cover collapse sinkholes, you climb down into the sinkhole, then you're in the lava tube where upstream is a lava tube and downstream is lava tube.
And you kind of walk downstream and then you get out through another cover collapse sinkhole. and you're sort of underground for a while, and then you pop out in another... Uh, another sinkhole. So it's easy to envision how a sinkhole would form in this pseudokarst setting, which is not dissolving rocks, but it's, it's creating cavities in the earth in a different way.
Chris Bolhuis: Another one that would fall into the category of [00:28:00] pseudocarst would be something on the order of, underground sewer pipes, let's say. This would be like an anthropogenic. Let's say a storm sewer running underground in front of a neighborhood, and that storm sewer pipe has a crack in it.
Well, during an event, that storm sewer is just full of water. It's over full, actually. And so when it hits that crack, water will shoot out of the ground, carrying sediment with it, washing away sediment around the pipe. And then after the event, or [00:28:30] after several events, it can have washed away enough sediment to cause it to collapse.
Thanks. I think big cities actually, this is somewhat of a problem, right? I mean, cracked pipes are, are not all that uncommon. And then, these things can develop. I had this actually in my front yard at my old house.
Yeah,
water would shoot out of it. Yeah, water would shoot out of that.
Like it looked like a geyser
After the storms, yeah after the storms I'd walk out to my front yard and and I'd have like this [00:29:00] cone shaped pile of just loose sand sitting right there you know, maybe a
Dr. Jesse Reimink: coming from underneath your house.
Chris Bolhuis: That's right. Well, no, it was out front. It was
Dr. Jesse Reimink: oh it's in the front yard, okay, but still, that
Chris Bolhuis: yard. Yeah.
Dr. Jesse Reimink: be on the surface, that should not be in the road or driveway, it should be in the ground.
Chris Bolhuis: No, I actually had to make phone calls to the township supervisor. Like this, this took a long time to get this taken care of because, people walking then, you know, alongside the road, along my front yard, I was worried about them stepping into this and breaking an ankle while it's on my property.
So that was something that I was really [00:29:30] concerned about actually, but this is, that's a pseudo Karst kind of setting right there too. So. an anthropogenic
Dr. Jesse Reimink: And a couple other different types of pseudocarst are like tectonic features, think of faults, or think of the San Andreas Fault, or different types of faults where basically the earth is opening up.
You can form cavities in the earth in a tectonically active scenario, usually in an extensional setting. So not at plate margin where there's convergence going on or subduction or [00:30:00] continent collision, but in an extensional setting, you can open up cavities in the earth this way. And one interesting one, Chris, was talus caves.
So think of a mountain side and you have this talus slope where the rocks are falling down, big boulders are falling down, and I was actually climbing around in some of these in Zion National Park, many, many years ago now, but basically that, the rock is eroding off and falling down and it's falling down and there's gaps underneath there.
And so water Can rush down these things and it won't move the boulders, but it will erode [00:30:30] stuff along the sides and underneath of the boulders. And eventually you'll form a cave there, you have a bunch of boulders stacked up in a little gap underneath, and then the soil develops on top of the boulders, you can get this what are called talus caves, which can then collapse down in on themselves later on.
And it can be this sort of feedback, and that can be a pseudo karst setting as well.
Another one, Chris, is just groundwater withdrawal. So, especially in areas where there's a limited amount of groundwater, groundwater takes up space in the earth, and if you withdraw or pump out a bunch [00:31:00] of groundwater, you can make a void down there, or at least it can create sort of the, this sort of slumping pattern.
They're usually more associated with The small or the slow collapse sinkholes, not the really violent one, but they, they are generating this pseudo karst nonetheless. So, I think, let me just summarize that karst is this topographic classification where rocks Under the surface are being dissolved and therefore cavities in the earth are being created, which are caves or [00:31:30] sinkholes or disappearing streams.
Pseudocarst is creating the same phenomenon, but not with dissolved rocks. It can create, gaps in the earth in various ways. We talked about volcanic tubes, sea cliffs can do this. We talked about talus slopes and, and anthropogenic, factors that can create. Voids in the earth.
Chris Bolhuis: Yeah. Right. this is where my mind goes when I think of Karst, I often think of the Black Hills. this ties into our earlier episode on disappearing streams,
Dr. Jesse Reimink: Well, Chris, this is the [00:32:00] beautiful thing about the black hills is like anything we talk about kind of brings to mind the black hills. Cause there's so much there. You know, there's so much geology there. It's amazing.
Chris Bolhuis: Yes. it's a very well kept secret and um, I, yeah, I
Dr. Jesse Reimink: And we're doing our best to change that.
Chris Bolhuis: I know I should, I should stop. Black Hills are a horrible place. my mind comes back to that, like I said, it ties into our earlier episode on disappearing streams and, the Black Hills have been in the news in the last, you know, what, three or four years because there have been a couple [00:32:30] of major sinkholes that have opened up that are related to true karst.
These are caves that have collapsed, but the collapse has happened where neighborhoods happen to be. And so it's actually been, kind of a, a sad, traumatic human story where, humanity and geology intersect once again because you have, you know, these people have really, they lost everything.
And so it's, it's made headlines. I actually came into contact with, some of the people that were brought in to explore these. [00:33:00] sinkholes. Yeah, they're these spelunkers because the black hills are a Mecca for caves, you have a lot of spelunkers that are really, really well renowned.
And they brought these people in to assess what's going on, one, and, uh, is it going to continue and is it safe? And, um, so anyway, I was, I came into contact with these people because this was actually during COVID. So, I was not able to take my students into, Wind Cave or Jewel Cave or anything like that, [00:33:30] right?
But these people took us into a, cave that is privately owned, it's called Bethlehem, and they were one, Spectacular people, very, very knowledgeable about the, not only the geology, but obviously caving. Um, and they just really took care of us, but this was, this grotto club was the, the same group that was brought in to assess the damage that has happened in the last couple of
Dr. Jesse Reimink: Oh, that's interesting. I mean, it's a really sort of, uh, sort of good point that juxtaposition [00:34:00] between sort of caving and, uh, and sinkholes, right? I mean, it's a really important thing. bringing up the Black Hills, when you look at this, this map of the US, we'll put a link to the paper, in the show notes, but when you look at the, Sinkhole Susceptibility Index Map of the U.
S. There's some real hot spots that stand out in the east coast of the United States, in Florida, sort of from Pennsylvania all the way down into Alabama where the Appalachians have exposed limestone or dolostone type rocks that are easy to dissolve, but the Black Hills stands out as well. You can see the [00:34:30] racetrack, you can see the circle, the ring of the Black Hills.
It's relatively low susceptibility on average around that, but there are really high points of really high susceptibility here, within that area. So, yeah, it's an interesting one. The Black Hills just really stands out on this map. I thought that was kind of, uh, cool to see. So,
Chris Bolhuis: it does. that racetrack that you alluded to is you pointed to it to me when we first started talking about this and I was amazed. I'm like, oh my gosh, you know, I've not seen this. I haven't seen this graphic before. And it, it just, it looks [00:35:00] like this perfect oval around the black
Dr. Jesse Reimink: yeah, it's a beautiful, a beautiful thing that traces out those, those rocks there. So, I think we've done this justice, Chris. I think we've kind of hit the, the highlights and the high points, and I think I've, um, been fairly nice to you this episode, so, uh, do you agree?
Chris Bolhuis: I do. I do. I do. Actually, I was the one that was rude. I called you a pseudo intellectual.
Dr. Jesse Reimink: Heh, Uh, hey, if it's accurate, then, you know, it's not rude. Hey, that's a wrap for this episode. You can follow us, uh, you can go to our website, planet geo [00:35:30] cast.com. There you can subscribe, you can support us. We always very much appreciate that when people support us and you can listen to all of our past episodes and learn more about us, send us an email, planet Geo cast@gmail.com.
Also our. New mobile app is up and running. So if you want access to Camp Geo, all the basics of geoscience with images that you need in audio discussion format, you can download the mobile app now on your, just go through your app store, either Android or iOS. And [00:36:00] so, head there, give us a like and a review and a rating on your podcast platform.
We really appreciate it.
Chris Bolhuis: Cheers.
Dr. Jesse Reimink: Peace.
