WEBVTT - Sinkholes, Part 1 0:00:03.040 --> 0:00:05.280 Welcome just about to blow your mind the production of 0:00:05.360 --> 0:00:14.120 My Heart Radio. Hey you welcome to stuff to blow 0:00:14.160 --> 0:00:17.440 your mind. My name is Robert Lamb and I'm Joe McCormick, 0:00:17.480 --> 0:00:20.760 and today we're gonna be talking about sink holes. This 0:00:20.840 --> 0:00:24.320 is actually, I think, in a way a listener requests 0:00:24.360 --> 0:00:27.760 topic that turned out to be very interesting. But it's, uh, 0:00:27.840 --> 0:00:30.720 it's sort of leap frogging off of some some previous 0:00:30.720 --> 0:00:33.360 episodes we did. Rob did the did the sink Whole 0:00:33.440 --> 0:00:35.720 journey begin when we were talking about the star Lac 0:00:35.880 --> 0:00:37.839 from Return of the Jedi. I think that was the 0:00:37.880 --> 0:00:40.800 original context. I think that was the original point at 0:00:40.800 --> 0:00:44.080 which we begin to hear listener males about the idea 0:00:44.080 --> 0:00:46.440 of that in a Sink Whole episode, because we talked 0:00:46.440 --> 0:00:49.240 about the star Lac and then we talked about some 0:00:50.280 --> 0:00:56.000 ideas and was it meso American uh mythology concerning uh 0:00:56.520 --> 0:00:59.440 entities of the ground that swallow things up? Oh, that 0:00:59.480 --> 0:01:01.000 could be at well, I know we ended up talking 0:01:01.040 --> 0:01:03.400 about the Bible, which will revisit in a minute here. 0:01:03.440 --> 0:01:06.039 But one of the questions that came up was, you 0:01:06.080 --> 0:01:09.080 know that scene in movies where there's an earthquake and 0:01:09.080 --> 0:01:11.760 and then suddenly a crack opens up in the middle 0:01:11.760 --> 0:01:14.080 of the street and it's you know, miles deep, and 0:01:14.080 --> 0:01:17.640 it just swallows people down into it. Uh. The question 0:01:17.760 --> 0:01:19.560 was like, does that kind of thing really happen? Does 0:01:19.920 --> 0:01:22.399 during an earthquake? Does the earth open up and open 0:01:22.440 --> 0:01:26.120 these deep pits and chasms that people fall down and 0:01:26.200 --> 0:01:29.880 disappear into. And our previous answer to that was, well, 0:01:30.080 --> 0:01:32.959 not really, or it seems like that's that's extremely rare 0:01:33.000 --> 0:01:35.400 if it ever happens. That's not like a common feature 0:01:35.640 --> 0:01:39.200 of what happens to the surface topology during an earthquake. 0:01:39.480 --> 0:01:43.200 But sinkholes, a listener pointed out, or a very different story. 0:01:43.200 --> 0:01:46.920 And sinkholes could explain many of these stories, uh, from 0:01:47.040 --> 0:01:49.320 from mythology and all that of the earth opening up 0:01:49.320 --> 0:01:51.120 and swallowing people. We can get back into that in 0:01:51.160 --> 0:01:53.240 a bit. But you actually turned up a really interesting 0:01:53.320 --> 0:01:58.320 photo essay about a fascinating sudden opening of a sinkhole. Uh, 0:01:58.560 --> 0:02:01.440 just earlier this year, that's right, Well, actually it was 0:02:01.520 --> 0:02:08.320 last year. God. Yeah, I haven't turned the calendar fully yet. 0:02:08.360 --> 0:02:11.240 It's still it's still It's like that year is kind 0:02:11.240 --> 0:02:13.640 of like the the other world in hell Raisers, So 0:02:13.680 --> 0:02:15.639 it's got chains with hooks and them, and they shoot 0:02:15.639 --> 0:02:17.560 out of the walls, and so the hooks are still 0:02:17.560 --> 0:02:21.240 in my brain, but I'm slowly methodically rebuilding my body 0:02:21.320 --> 0:02:24.919 to escape. All right, Well, this is this story takes 0:02:25.000 --> 0:02:29.280 us back to April. So, um, what happened is a 0:02:29.400 --> 0:02:31.640 whole opened up in the front yard of a home 0:02:31.720 --> 0:02:36.280 in Black Hawks, South Dakota. UH, specifically in a housing 0:02:36.320 --> 0:02:41.120 development there that was called, perfectly enough, the Hideaway Hills development. 0:02:43.040 --> 0:02:45.000 That just doesn't sound great. I mean, no offense the 0:02:45.000 --> 0:02:47.480 people who lived there, but it doesn't sound like a 0:02:47.520 --> 0:02:49.000 place I want to go. It sounds like a place 0:02:49.080 --> 0:02:51.160 where I don't know where you like retreat after you've 0:02:51.160 --> 0:02:55.560 committed a crime. What was the housing development? Unarrested development, 0:02:55.720 --> 0:03:02.080 Sudden Valley or Sudden Yeah? Yeah appropriate as well. So Um, 0:03:02.720 --> 0:03:05.680 like you pointed out, there's an incredible photo essay photo 0:03:05.760 --> 0:03:08.280 series on this on board Panda about this. If you 0:03:08.280 --> 0:03:11.880 look up board Panda, Black South Dakota Sinkhole, you will 0:03:11.919 --> 0:03:16.320 find it because uh this photo essay, if you will. 0:03:16.400 --> 0:03:20.120 It takes us through a journey by a local caving 0:03:20.160 --> 0:03:24.760 group called Pahsapa Grotto as they decided to venture down 0:03:24.800 --> 0:03:27.079 into this hole that opened up in this front yard 0:03:27.360 --> 0:03:31.720 to explore the world beneath the suburbs. Now, this sinkhole, 0:03:32.200 --> 0:03:34.040 it turns out it's going to be very different than 0:03:34.160 --> 0:03:36.720 most of the sinkholes we're talking about in this episode. 0:03:37.280 --> 0:03:42.280 Most sinkholes open up over some kind of void that 0:03:42.440 --> 0:03:44.280 is formed in the rock below, and as we'll get 0:03:44.320 --> 0:03:45.920 into a lot of that usually has to do with 0:03:46.320 --> 0:03:49.600 water and hydrology. But in this case, the void in 0:03:49.720 --> 0:03:53.120 the rock below the neighborhood was was more was of 0:03:53.160 --> 0:03:56.240 a more artificial persuasion, right. That's because there was an 0:03:56.240 --> 0:04:00.440 abandoned gypsum mine beneath the housing development, and so the 0:04:00.480 --> 0:04:02.920 cavers had they had to lower down in on ropes, 0:04:03.320 --> 0:04:06.160 you know, had to use like actual caving equipment into 0:04:06.160 --> 0:04:10.000 the dark and sometimes flooded tunnels beneath reportedly over two 0:04:10.040 --> 0:04:12.880 thousand feet across in a hundred and fifty feet why 0:04:13.080 --> 0:04:16.880 this tunnel um complex, uh And they encountered the remains 0:04:16.920 --> 0:04:19.920 of what looks like an old like nineteen fifties automobile. 0:04:20.560 --> 0:04:23.320 There's just a whole world down there, like a whole 0:04:23.720 --> 0:04:28.880 uh Minoan maze beneath this you know, rather mundane looking 0:04:28.920 --> 0:04:32.120 housing development. It's like two levels of weird. So first 0:04:32.120 --> 0:04:35.160 of all, it's yes, the suburban, you know, neighborhood. And 0:04:35.200 --> 0:04:37.920 then just in the middle of somebody's front yard a 0:04:38.360 --> 0:04:41.279 pit opens up, so that's the sinkhole. But then it's 0:04:41.400 --> 0:04:44.520 that the sinkhole goes to this maze and yeah, like 0:04:44.560 --> 0:04:46.880 you said, there's like an old Chevy convertible down there, 0:04:47.160 --> 0:04:49.440 and I'm wondering, why is that down there? Did somebody 0:04:49.520 --> 0:04:52.800 drive it into the mind before the mine was sealed up? Yeah, 0:04:52.839 --> 0:04:54.680 I don't know, Like, it's just it's a place full 0:04:54.720 --> 0:04:58.120 of questions, is a place full of the past, of mysteries, 0:04:58.560 --> 0:05:00.760 and so the article it's gets into some of the 0:05:00.800 --> 0:05:03.279 community fall out over all this. But but what I 0:05:03.320 --> 0:05:06.280 love about this episode is it illustrates for us this 0:05:06.360 --> 0:05:10.360 divide between the surface world, so tightly manicured and controlled 0:05:10.560 --> 0:05:13.039 so much of the time, and a world beneath that 0:05:13.120 --> 0:05:16.240 we have only a shaky understanding of, like something out 0:05:16.240 --> 0:05:19.640 of a mash up between Poltergeist and The Descent. You know, 0:05:19.960 --> 0:05:23.159 a gateway to that hidden underworld might open up at 0:05:23.160 --> 0:05:26.839 any moment and reveal its secrets to us, invite us in, 0:05:27.040 --> 0:05:30.760 perhaps swallow us entirely, and then we'll be part of 0:05:30.800 --> 0:05:34.679 that underworld. Because if we're being you know, perfectly rational 0:05:35.720 --> 0:05:40.040 without any supernatural ideas like that, that idea alone is terrifying. 0:05:40.080 --> 0:05:42.680 You know that the earth might open up and we 0:05:42.760 --> 0:05:45.680 might fall, you know, into a pit. But then if 0:05:45.720 --> 0:05:49.039 you begin to layer in beliefs and superstitions, then yeah, 0:05:49.120 --> 0:05:53.080 become this whole becomes a portal to other realms. Yeah, exactly. 0:05:53.080 --> 0:05:56.239 Now we've talked about natural features in the landscape taking 0:05:56.240 --> 0:05:58.920 on religious significance before, Like in we did a couple 0:05:58.920 --> 0:06:02.080 of episodes called The Acred Mountain, which was about mountain 0:06:02.120 --> 0:06:05.200 peaks that were considered to be holy or supernatural or 0:06:05.240 --> 0:06:08.240 the dwelling places of gods or places that Win explored. 0:06:08.279 --> 0:06:12.120 People often reported having supernatural experiences. They're like One of 0:06:12.120 --> 0:06:13.719 the things that came out of that was the the 0:06:13.800 --> 0:06:18.040 often reported third man syndrome, feeling that mountain climbers sometimes 0:06:18.120 --> 0:06:20.680 have very high up But we talked about possible ways that, 0:06:21.120 --> 0:06:24.560 like the effects of the sun or that altitude sickness 0:06:24.560 --> 0:06:28.840 could contribute to that um But there are also ways 0:06:28.880 --> 0:06:33.200 in which sinkholes can take on similar types of religious significance, 0:06:33.240 --> 0:06:37.160 can have a similar mythological appeal, and One great example 0:06:37.279 --> 0:06:40.120 is we is some of the sinkholes are also known 0:06:40.160 --> 0:06:43.080 as sinots that we see throughout Mesoamerican religion and the 0:06:43.120 --> 0:06:46.920 Yucatan Peninsula and among the ancient Mayan people. But I 0:06:46.960 --> 0:06:49.560 guess well, we'll come back to that more later. I 0:06:49.839 --> 0:06:53.200 wanted to get to this question about the the idea 0:06:53.360 --> 0:06:55.920 that the earth can open up and swallow you. It's 0:06:55.960 --> 0:06:59.400 an image that seems like to perfectly fit ancient myths 0:06:59.440 --> 0:07:02.719 and texts that you would imagine passages like this appearing 0:07:02.760 --> 0:07:05.800 in you know, Babylonian texts or something. It definitely appears 0:07:05.800 --> 0:07:08.960 in the Hebrew Bible, for example, in the Book of Numbers, 0:07:09.000 --> 0:07:11.400 there's a passage where Moses is speaking to people and 0:07:11.440 --> 0:07:13.920 he's trying to demonstrate that he was in fact sent 0:07:14.000 --> 0:07:17.280 by the Lord. And he uh he, he says, and 0:07:17.600 --> 0:07:19.800 basically he makes a promise that hey, if the Lord 0:07:19.800 --> 0:07:22.280 has sent me, he'll he'll send a sign and you'll 0:07:22.320 --> 0:07:25.080 know it because there will be this group of people 0:07:25.160 --> 0:07:27.720 that will be swallowed up alive into a pit that 0:07:27.840 --> 0:07:30.520 opens up suddenly in the earth for for these wicked 0:07:30.520 --> 0:07:33.800 people who have rejected the Lord. And the passage says 0:07:33.840 --> 0:07:36.000 in uh. In the book of numbers. Now it came 0:07:36.040 --> 0:07:38.480 to pass, as he finished speaking all these words, that 0:07:38.560 --> 0:07:41.360 the ground split apart under them, and the earth opened 0:07:41.400 --> 0:07:44.400 its mouth and swallowed them up with their households, and 0:07:44.480 --> 0:07:46.960 all the men of Cora, with all their goods. So 0:07:47.040 --> 0:07:49.560 they and all those with them went down alive into 0:07:49.600 --> 0:07:52.640 the pit. The earth closed over them, and they perished 0:07:52.680 --> 0:07:56.200 from among the assembly. And so I wonder, I mean, obviously, 0:07:56.200 --> 0:07:59.040 with passages like this, I wonder if it's this kind 0:07:59.040 --> 0:08:01.800 of thing that inspire that scene in every movie that 0:08:01.880 --> 0:08:04.400 has an earthquake in it where suddenly a bottomless pit 0:08:04.480 --> 0:08:07.920 opens up in the ground and people get sucked into it. Yeah, 0:08:08.120 --> 0:08:11.000 you know, this could also be graboids. If I think, 0:08:11.000 --> 0:08:13.560 if they want to make another Tremor's film, which they will, 0:08:13.680 --> 0:08:17.000 I'm sure they should go for, you know, some biblical 0:08:17.040 --> 0:08:19.840 flare here, go for an Old Testament Tremor's movie with 0:08:19.840 --> 0:08:22.800 with Moses being our central character. And that's a very 0:08:22.840 --> 0:08:25.240 good direction. Now, one thing I want to say, because 0:08:25.560 --> 0:08:27.000 I feel like I have to bring this up every 0:08:27.040 --> 0:08:30.600 time we talk about geo mythology. Uh, there's this question 0:08:30.680 --> 0:08:34.000 of is this story in the Bible based on something 0:08:34.080 --> 0:08:38.800 that's someone in history witnessed witnessing a real world geological event, 0:08:39.080 --> 0:08:42.199 perhaps a sudden collapse of a settled area due to 0:08:42.240 --> 0:08:44.560 a sinkhole. Uh. And, as I pretty much always do 0:08:44.600 --> 0:08:47.000 whenever we talk about geomethology, I want to emphasize that 0:08:47.080 --> 0:08:50.680 fantastic imagery and in myths and legends and religious text 0:08:50.760 --> 0:08:55.120 doesn't necessarily need to be explained by someone actually having 0:08:55.200 --> 0:08:57.319 seen something physical in the world. I think we can 0:08:57.360 --> 0:09:01.600 sometimes go overboard looking for natural, realistic explanations of this 0:09:01.679 --> 0:09:04.600 kind to explain what somebody thought they saw that appears 0:09:04.600 --> 0:09:07.200 in a story. You know, people are highly imaginative, and 0:09:07.240 --> 0:09:10.960 sometimes stories are just stories. But there's always also the 0:09:11.000 --> 0:09:14.040 possibility that stories like these could be based on people 0:09:14.080 --> 0:09:16.840 hearing stories about having seen I don't know, there was 0:09:16.880 --> 0:09:18.880 a there was a castle or a building or something 0:09:18.920 --> 0:09:21.040 like that that was just swallowed up into the earth, 0:09:21.400 --> 0:09:24.600 which if you didn't have any kind of geological understanding 0:09:24.640 --> 0:09:27.959 with which to to interpret that, it would certainly seem 0:09:28.000 --> 0:09:30.240 to be a you know, a supernatural event. I don't know, 0:09:30.240 --> 0:09:32.319 I don't know how else you would interpret it. Yeah, 0:09:32.360 --> 0:09:35.040 Because I think one of the things that really drives 0:09:35.040 --> 0:09:38.040 home and when we we see examples of sinkholes, and 0:09:38.120 --> 0:09:41.480 we hear stories like this, we see cinematic interpretations. Is 0:09:41.559 --> 0:09:46.920 that idea that the that terra firma is not that firm, 0:09:47.080 --> 0:09:49.720 is not that fixed, that it could change, that the 0:09:50.000 --> 0:09:53.880 that the firm ground beneath our feet could suddenly give way, 0:09:54.040 --> 0:09:56.920 you know, like that alone is just this kind of 0:09:57.360 --> 0:10:01.599 uh you know, horrifying idea. Uh that that it that 0:10:01.720 --> 0:10:04.280 it easily applies as a metaphor to everything else in 0:10:04.320 --> 0:10:06.840 our in our life. You know, that the thing that 0:10:06.960 --> 0:10:10.240 is the order that we depend upon might go away 0:10:10.240 --> 0:10:12.560 at any moment. Yeah, it's interesting to think about like 0:10:12.559 --> 0:10:16.720 a vertical spectrum of of ways that the natural world 0:10:16.800 --> 0:10:19.480 can intrude on our lives and how most of the 0:10:19.480 --> 0:10:22.000 stuff that we're that we're used to thinking about taking 0:10:22.000 --> 0:10:26.080 into consideration, worrying about as as possible threats, all basically 0:10:26.160 --> 0:10:28.520 takes place like on the surface of the Earth. And 0:10:28.600 --> 0:10:31.000 that you know, when you go to the vertical ends 0:10:31.040 --> 0:10:33.880 of that spectrum, you've got like impacts from space coming 0:10:33.920 --> 0:10:37.480 from above, sinkholes, oupening opening up from below, and these 0:10:37.480 --> 0:10:42.400 phenomena intrude on that day to day understanding of physical forces. Yeah, 0:10:42.440 --> 0:10:44.760 so it's it's no surprise We were talking about this 0:10:45.000 --> 0:10:48.040 before the podcast started rolling here that if you start 0:10:48.120 --> 0:10:52.680 looking around for sinkholes online, you'll find just so many galleries, 0:10:52.800 --> 0:10:57.120 top ten lists, lots of click bade about sinkholes. Like 0:10:57.200 --> 0:11:00.199 sinkholes are kind of they're kind of like a like 0:11:00.280 --> 0:11:04.480 they're kind of like true crime. You know, they're um there. 0:11:04.679 --> 0:11:06.760 You also see them, like I was noticing like very 0:11:06.840 --> 0:11:10.160 tabloid sites, sites that otherwise they're not going to really 0:11:10.200 --> 0:11:14.040 have anything related to geology, but they'll have sinkholes. You know, 0:11:14.080 --> 0:11:17.680 it'll be celebrity gossip, um, and you know, maybe some 0:11:17.800 --> 0:11:21.400 conspiracy theories. But then also uh, big old holes opening 0:11:21.480 --> 0:11:23.880 up in the earth. Chump boxes are full of sinkholes. 0:11:23.920 --> 0:11:26.480 Have you ever noticed this? These are the like the 0:11:26.559 --> 0:11:30.840 link um grids at the bottom of blogs and whatnot. Yeah. Yeah, So, like, 0:11:31.080 --> 0:11:34.319 you know, like most websites on the Internet these days 0:11:34.320 --> 0:11:37.360 are just being more and more infected by ads that 0:11:37.440 --> 0:11:40.480 essentially take the form of malware. But if you scroll 0:11:40.559 --> 0:11:43.440 down to the bottom of most articles or any text 0:11:43.480 --> 0:11:46.040 image based website, you'll usually see one of these boxes 0:11:46.120 --> 0:11:50.920 that's full of just like extremely tacky, distasteful images that 0:11:50.960 --> 0:11:54.079 are either like something that's kind of sexually suggestive and 0:11:54.120 --> 0:11:58.320 a gross way or something that is uh has some 0:11:58.440 --> 0:12:01.199 kind of like health vibe, like it looks like infected 0:12:01.280 --> 0:12:05.360 skin or holes in skin, or some kind of bite 0:12:05.520 --> 0:12:09.960 or something like the kind of a necrotic bite that 0:12:10.000 --> 0:12:12.520 you might imagine someone would get in their worst nightmares 0:12:12.559 --> 0:12:14.640 from a brown recluse, you know that kind of thing. 0:12:15.240 --> 0:12:18.680 Um yeah, they they tie into our like deepest most 0:12:18.760 --> 0:12:23.880 primal fears and desires, just pure eroticism or just pure 0:12:25.080 --> 0:12:29.400 necrotic damage or indeed holes opening up in the earth. 0:12:29.440 --> 0:12:31.360 You know, it's got to be something extreme like that 0:12:31.400 --> 0:12:34.160 to make it into that grid of horror. Yeah, the 0:12:34.200 --> 0:12:37.079 toilet with the rat coming up through it? Remember that one? 0:12:37.400 --> 0:12:38.760 Oh yeah, I think I've seen that one. That was 0:12:38.800 --> 0:12:41.480 a common chumbox image or the like. You know, doctors 0:12:41.480 --> 0:12:43.840 say never eat this vegetable, but they don't tell you 0:12:43.880 --> 0:12:47.040 what it is. Yeah yeah, yeah, sometimes it is um it. 0:12:47.520 --> 0:12:50.080 It's economic as well. You know, there'll be some sort 0:12:50.160 --> 0:12:52.480 generally it's like a picture of an old person and 0:12:52.559 --> 0:12:56.360 just a few like alarming words about you know, investments 0:12:56.400 --> 0:12:59.440 or retirement or something. Right, but that is the world 0:12:59.440 --> 0:13:02.440 will single are actually in their own way. I mean, 0:13:02.480 --> 0:13:04.760 of course, they can be horrifying, they can be destructive 0:13:04.760 --> 0:13:07.480 to human life, but they are also fascinating in their 0:13:07.480 --> 0:13:10.959 own way, in a natural way, they are wonderful. Uh. 0:13:11.160 --> 0:13:15.359 There can be beautiful uh legends and stories attached to them, 0:13:15.440 --> 0:13:17.559 and so I don't know, I feel like they are 0:13:17.760 --> 0:13:22.000 the most uh naturally beautiful thing that that fits in 0:13:22.040 --> 0:13:24.840 the chum box. I mean the rat and the toilet 0:13:24.920 --> 0:13:26.920 can't compete. I mean the rat and the toilet. We 0:13:26.920 --> 0:13:28.960 could do an episode on that as well. But yeah, 0:13:29.160 --> 0:13:31.480 I agree, the sinkholes need to be rescued from the 0:13:31.800 --> 0:13:34.520 chum box. Uh. And that's kind of what we're doing 0:13:34.559 --> 0:13:36.800 in in this episode of stuff to blow your mind 0:13:36.800 --> 0:13:47.000 and the possible second episode to fall. Alright, So sinkholes 0:13:47.000 --> 0:13:50.600 are formed in a number of ways, but most naturally 0:13:50.640 --> 0:13:54.160 occurring sinkholes, like most other things on planet Earth, in 0:13:54.200 --> 0:13:57.600 the end, come back to the power of water. Water, 0:13:57.640 --> 0:14:00.240 of course, is the molecule of life, largely be because 0:14:00.280 --> 0:14:03.960 of its power as a master solvent, and in much 0:14:04.000 --> 0:14:06.800 the same way really that water created life on Earth, 0:14:06.880 --> 0:14:11.720 probably it also creates many of Earth's most astounding geologic features. 0:14:12.280 --> 0:14:14.720 And so this is how we we get sinkholes. For 0:14:14.760 --> 0:14:17.480 the most part so as carbon dioxide in the air 0:14:17.720 --> 0:14:22.840 or in the soil mixes with rainwater, that mixture forms 0:14:22.880 --> 0:14:26.120 a weak acid with the with the chemical formula H 0:14:26.200 --> 0:14:28.680 two c O three. So what you've got there is 0:14:28.680 --> 0:14:30.520 you've got your H two oh the water, and then 0:14:30.520 --> 0:14:33.560 you've got your C O two the carbon dioxide. They react, 0:14:33.640 --> 0:14:36.240 they make a compound with two hydrogens, one carbon and 0:14:36.320 --> 0:14:40.640 three oxygen's And this weak acid formed in the atmosphere 0:14:40.760 --> 0:14:43.800 or in the soil is known as carbonic acid, and 0:14:43.960 --> 0:14:48.480 it is the primary reason that caves exist. Now most 0:14:48.560 --> 0:14:51.920 caves in the world, not all, but most are formed 0:14:52.040 --> 0:14:56.320 by the drainage of acidified water through what you might 0:14:56.400 --> 0:15:01.120 call soluble rock, and uh soluble rock types of rock 0:15:01.280 --> 0:15:05.280 that can react chemically with this water and be dissolved 0:15:05.320 --> 0:15:08.440 and carried away now they're There are multiple kinds of 0:15:08.480 --> 0:15:13.400 soluble rock, including minerals like salt and gypsum, But probably 0:15:13.440 --> 0:15:16.800 the most important, or at least the most charismatic, is limestone, 0:15:16.920 --> 0:15:21.120 which is in itself a fascinating and even mind boggling rock. 0:15:21.200 --> 0:15:25.120 And sometimes I really do think a lot about limestone, 0:15:25.160 --> 0:15:29.120 and maybe people are aren't inclined to be as impressed 0:15:29.160 --> 0:15:30.960 by it as I am. But if you don't believe 0:15:30.960 --> 0:15:34.000 me that limestone is amazing, I think it's worth considering 0:15:34.280 --> 0:15:36.800 that if you live in an area of the world 0:15:36.880 --> 0:15:39.240 you know this primarily resting on limestone, which in the 0:15:39.320 --> 0:15:42.920 United States would include huge portions of like Florida and 0:15:42.920 --> 0:15:46.080 the coastal southeast, big parts of the Midwest. If you 0:15:46.120 --> 0:15:48.720 live in a place like that dominated by this this 0:15:48.840 --> 0:15:52.880 carbonate rock, you are walking around every day on rock 0:15:53.000 --> 0:15:57.360 that is probably mostly built out of dead bodies. Limestone 0:15:57.400 --> 0:15:59.200 can be formed in a number of ways. Some of 0:15:59.240 --> 0:16:01.480 those ways are a biotic, but one of the major 0:16:01.640 --> 0:16:06.800 processes that forms limestone is the gradual deposition of the 0:16:06.920 --> 0:16:11.720 shells and other hard calcium carbonate body parts of animals 0:16:11.720 --> 0:16:14.920 and other tiny organisms in the oceans and rivers and 0:16:15.040 --> 0:16:19.120 lakes where they accumulate on the bottoms of these water 0:16:19.200 --> 0:16:23.800 sources over millions of years, and apparently feces also in general, 0:16:23.800 --> 0:16:28.120 waste products can contribute as well. So the calcium based 0:16:28.160 --> 0:16:32.040 body parts of algae and coral and oysters and all 0:16:32.120 --> 0:16:35.320 kinds of creatures of the sea settle in the deep 0:16:35.640 --> 0:16:38.480 and then they're pressed down and paved over by time 0:16:38.520 --> 0:16:43.240 and pressure until they become layers of sedimentary rock. I 0:16:43.360 --> 0:16:47.000 really just think about that. Sometimes limestone is largely made 0:16:47.000 --> 0:16:50.640 out of life that has died and become rock, like 0:16:50.680 --> 0:16:53.720 the fallen creatures of Earth pile up and become part 0:16:53.720 --> 0:16:56.880 of the crust of the Earth itself. Wow, it's like 0:16:56.960 --> 0:16:59.800 it's like the Medusa's layer, right, just all these the 0:17:00.640 --> 0:17:03.040 petrified bodies. Oh, that's I wish I had thought of 0:17:03.080 --> 0:17:05.600 that when we were doing our Medusa episodes, except I 0:17:05.640 --> 0:17:08.080 guess in the Medusa Garden that they keep their form 0:17:08.240 --> 0:17:10.960 right here. They just sort of like go back to 0:17:11.080 --> 0:17:15.439 whence they came. They become part of this mass. But anyway, 0:17:15.480 --> 0:17:18.720 it's via rocks like this that we get so many 0:17:18.760 --> 0:17:21.639 of the naturally occurring sinkholes on the Earth. So how 0:17:21.720 --> 0:17:24.480 do they form? Well, imagine that there is a storm, 0:17:24.520 --> 0:17:26.919 it rains here in an area with some kind of 0:17:26.960 --> 0:17:29.400 soluble rock, let's say it's a it's a carbonate rock, 0:17:29.440 --> 0:17:33.240 it's like limestone, and rainwater collects on the surface of 0:17:33.240 --> 0:17:36.400 the earth and then runs downhill. And if that rainwater 0:17:36.560 --> 0:17:41.640 drains down into cracks insoluble rock like limestone, things begin 0:17:41.680 --> 0:17:43.640 to happen much in the same way that you can 0:17:43.680 --> 0:17:46.440 dissolve table salt or sugar and a glass of water. 0:17:46.920 --> 0:17:50.680 The crystal contents of these soluble rock surfaces are gradually 0:17:50.720 --> 0:17:55.200 dissolved in and carried away by that acidified water, and 0:17:55.280 --> 0:17:58.920 over tens or hundreds of thousands of years, that dissolution 0:17:59.000 --> 0:18:01.680 of the rock by a water can turn what might 0:18:01.680 --> 0:18:04.879 have started as this tiny stress fracture in a chunk 0:18:04.880 --> 0:18:08.639 of bedrock into an underground cavern large enough for a 0:18:08.720 --> 0:18:11.520 human to climb into. And of course, as the centuries 0:18:11.600 --> 0:18:15.440 go on, these these voids created by the drainage pathways 0:18:15.480 --> 0:18:18.200 of water can just get bigger and bigger. They can 0:18:18.240 --> 0:18:22.359 form underground rivers that form larger and larger voids. And 0:18:22.440 --> 0:18:25.959 it's this dissolution of soluble rock by water that usually 0:18:26.040 --> 0:18:29.400 leads to the creation of sinkholes. Uh though these voids 0:18:29.400 --> 0:18:32.800 in the rock I think sometimes maybe geologists will get 0:18:32.800 --> 0:18:35.760 picky about this. These voids in the rock are not 0:18:35.920 --> 0:18:39.159 technically themselves sinkholes, and we would normally think of them 0:18:39.160 --> 0:18:43.400 as voids or just caves right their caves in the rock. Um. Rather, 0:18:43.520 --> 0:18:47.879 a sinkhole is more of a topographical designation. It's a 0:18:47.920 --> 0:18:51.679 topographical concept about the ground and the surface of the earth. 0:18:52.320 --> 0:18:55.600 So according to the U. S Geological Survey, a sinkhole 0:18:55.680 --> 0:18:58.800 is quote an area of ground that has no natural 0:18:59.040 --> 0:19:03.399 external surface drainage. So like in one of these areas, 0:19:03.400 --> 0:19:06.880 if it rains, water just pools in, and there's nowhere 0:19:06.880 --> 0:19:10.560 on the surface level that allows this water to run out. 0:19:10.800 --> 0:19:13.520 So if the water leaves, it's either evaporating into the 0:19:13.520 --> 0:19:17.600 air or it's draining out through somewhere in the bottom. Sinkholes, 0:19:17.640 --> 0:19:21.159 of course, can form gradually over hundreds or hundreds of 0:19:21.200 --> 0:19:24.520 thousands of years, often of steady dissolution, or they can 0:19:24.560 --> 0:19:27.960 form quite suddenly, for example, when the ground over a 0:19:28.040 --> 0:19:32.040 void in the limestone below is suddenly just suddenly there's 0:19:32.080 --> 0:19:34.040 not enough for it to support its own weight, and 0:19:34.080 --> 0:19:37.120 then it just collapses and reveals the void that had 0:19:37.119 --> 0:19:39.960 been there for so long. Uh. And we know that 0:19:39.960 --> 0:19:42.520 the sudden appearance of a sinkhole can have these devastating 0:19:42.560 --> 0:19:45.800 effects on human settlements and uh whatever is lying on 0:19:45.840 --> 0:19:48.320 the surface, which will get into more later, but it 0:19:48.359 --> 0:19:53.120 can also have strange otherworldly effects simply on the geological 0:19:53.480 --> 0:19:57.480 and hydrological landscape itself. And I wanted to share one 0:19:57.520 --> 0:20:00.359 amazing example that I came across while I was reading 0:20:00.400 --> 0:20:03.480 up for this episode. This was the opening paragraph in 0:20:03.640 --> 0:20:07.320 an article for The New Yorker by David Owen. There 0:20:07.359 --> 0:20:10.960 was an article about sinkholes called Notes from Underground, and this, 0:20:10.960 --> 0:20:13.359 this paragraph really gave me chills when I got to 0:20:13.359 --> 0:20:15.560 the end of it. So if you don't mind, I 0:20:15.600 --> 0:20:18.040 just want to share this year. In the fall of nine, 0:20:19.119 --> 0:20:23.080 much of Lake Jackson, a four thousand acre natural body 0:20:23.119 --> 0:20:26.440 of water just north of Tallahassee and a popular site 0:20:26.480 --> 0:20:30.879 for fishing, water skiing, and recreational boating, disappeared down a 0:20:30.960 --> 0:20:35.800 hole like a bathtub, emptying into a drain trophy. Bass 0:20:35.840 --> 0:20:40.119 became stranded in rapidly shrinking eddies, enabling children to catch 0:20:40.200 --> 0:20:43.159 them with their hands and toss them into picnic coolers, 0:20:43.640 --> 0:20:46.600 and many of the lake's other fish, turtles, snakes, and 0:20:46.640 --> 0:20:51.240 alligators vanished into the earth. At various times during the 0:20:51.280 --> 0:20:56.160 next few years, the lake partially refilled, redrained, and refilled again. 0:20:57.040 --> 0:21:00.720 Jonathan Arthur, who is Florida's state geologist and the director 0:21:00.720 --> 0:21:03.920 of the Florida Geological Survey, was among several people who, 0:21:04.000 --> 0:21:07.960 during a dry period, descended a ladder into the main opening, 0:21:08.160 --> 0:21:11.600 which was about eight feet in diameter. Quote, you could 0:21:11.600 --> 0:21:14.720 climb down twelve feet or so and then walk under 0:21:14.760 --> 0:21:17.840 the lake bed. He told me recently. I hadn't gone 0:21:17.960 --> 0:21:20.800 very far before my red flags went up, and I 0:21:20.840 --> 0:21:26.240 was like, maybe I won't go any farther. So that image, 0:21:26.320 --> 0:21:28.840 it combined with the way it's phrase that that really 0:21:28.880 --> 0:21:32.200 gave me goose bumps. Yeah. Yeah, the idea of yeah, 0:21:32.200 --> 0:21:33.960 I mean, it really feels like like a place you 0:21:34.000 --> 0:21:36.919 do not belong that you know, the the cave beneath 0:21:36.960 --> 0:21:40.440 the lake that is. Yeah, that that that could potentially 0:21:40.480 --> 0:21:42.639 fill back up at any moment. Well. And also, I 0:21:42.640 --> 0:21:45.240 mean I think anybody who, especially people who do like 0:21:45.240 --> 0:21:50.200 scuba diving and stuff, are made uniquely aware of the 0:21:50.320 --> 0:21:55.280 dangers of of being in places that combine water and 0:21:55.440 --> 0:22:00.000 overhead rock. Like, yes, about that that can be an 0:22:00.160 --> 0:22:06.760 specially dangerous and and suddenly dangerous, surprisingly dangerous combination of features. Yeah, 0:22:06.760 --> 0:22:09.119 I mean, even if you are an experienced cave diver, 0:22:10.600 --> 0:22:14.560 cave diving is dangerous. Uh so, um so yeah, that 0:22:14.680 --> 0:22:18.719 is a dangerous realm to to go down into for sure. Now, 0:22:18.720 --> 0:22:20.960 I figured it would be worth talking about a few 0:22:20.960 --> 0:22:24.560 of the different ways that natural sinkholes form um Obviously 0:22:24.600 --> 0:22:26.480 things will be a little bit different if you're talking 0:22:26.480 --> 0:22:29.680