Geology of Jewel Cave
Transcript
00:00:04 Hello and welcome to Jewel Cave National Monument’s 125 years of Discovery Podcast, Discovery Hour. 00:00:11 Join us this episode as we listen to a presentation on the formation of Jewel Cave presented by Mike Wiles, Jewel Cave’s Chief of Resource Management. 00:00:21 Recorded on January seventeenth, two thousand and twenty five. 00:00:24 A transcript of this episode is available on our website, www.NPS.GOV/JECA 00:00:31 thank you for listening. 00:00:52 Audiences of any size, OK, but there's just a little bit different world when. 00:00:56 Speaking out loud to everybody. Yeah, yeah, yeah. 00:00:59 Just. 00:01:00 About. 00:01:01 Yep. 00:01:01 It's kind of like a tour with thirty people versus three. 00:01:06 OK. 00:01:07 So I my name is Mike Wiles. 00:01:10 I've been here forty five years. 00:01:12 News. 00:01:13 It started out as a volunteer cave explorer. 00:01:17 I I got indicating when I was. 00:01:21 In at South Dakota School of Mines and I got a master or a Bachelors in chemical engineering which? 00:01:30 But that's where I ran into a group of cavers that started. 00:01:35 Caving. 00:01:37 Then I went back. 00:01:39 Several years later and got a master 's in geological engineering. 00:01:45 And I wrote my thesis on the infiltration of groundwater at Wind Cave. 00:01:48 Jewel cave. 00:01:51 Have you ever visited any of the caves on the East Coast? 00:01:55 I've been on some in like one in North Carolina. 00:01:59 What about West Virginia? 00:02:00 I've been in West Virginia. 00:02:01 What was it? 00:02:02 You remember. 00:02:03 Bowden 's cave. 00:02:04 There's one right off of the highway. 00:02:06 It might be a. 00:02:07 The real popular. 00:02:09 You know, school kid. 00:02:11 You know, because it's just off the highway. 00:02:13 If that's the one that. 00:02:15 Toured this past fall. 00:02:16 Well it. 00:02:17 It was not a developed cave. 00:02:19 OK, gotcha. OK. 00:02:19 It was just a wild cave. 00:02:22 And I've been in some caves down where Tennessee, Alabama and Georgia intersect. 00:02:30 So what were those? 00:02:31 I've been to a few of. 00:02:32 That's my area. 00:02:33 I don't. 00:02:34 Some of that was for Ncrc rescue training. 00:02:38 So that's just where we had our operations and I don't remember. 00:02:41 Names OK. 00:02:42 Yeah, I've done like temporary work. 00:02:43 Yes. 00:02:44 And. 00:02:46 I might have. 00:02:49 Been the compliment. 00:02:52 A long time ago. OK. 00:02:54 Yeah, so I'm right. 00:02:56 So that's a little bit of my. 00:02:59 Now when? 00:02:59 Started. I didn't know anything about geology. 00:03:02 I started caving. 00:03:04 So where do you find caves? 00:03:06 Well, they're in limestone. 00:03:08 What's limestone? 00:03:09 Well, this is limestone and that's different than this, which is sandstone. 00:03:14 Sometimes they kind of look the same until you get up close. You know once you. 00:03:18 Your eye. 00:03:18 To it. You know what it. 00:03:19 So that was my first geological information was. 00:03:23 Limestone and sandstone. 00:03:26 I ended up really falling in love with caving and that's why I went back to school. 00:03:30 For geological engineering and there really wasn't much in the curriculum that talks specifically about. 00:03:36 So I had to kind of do a lot of things and special projects on my own to in order to get some of that cave stuff. And I learned a bit from. 00:03:47 Some old time professors, a couple of them, are still alive. 00:03:51 Most of them have passed away. 00:03:52 Who really were kind of experts in their field and they did personally share with me some of their views of The Cave, but there just wasn't much written about the caves here in the Black Hills. 00:04:04 So I would take with what I learned and when I went caving here, I would try to apply that. 00:04:11 You know what I saw in the? 00:04:13 It turned out an awful lot of what people said wasn't true. 00:04:19 I could see how there was that impression. You know, for instance, when dual cave was only a few miles long, you could draw a conclusion. But by the time you got up to a hundred and fifty miles long, that conclusion. 00:04:33 It it was, it was. 00:04:34 Was obviously didn't happen. 00:04:36 So that was kind of the beginning of my experience of. 00:04:40 Kind of learning to figure out. 00:04:42 Cave for myself. 00:04:44 And one of the good great advantages is I've been here forty five years. 00:04:48 I can ponder over things and things that seem right, but later don't seem right. 00:04:53 Can figure it out again. 00:04:56 Where almost all geological stuff is done under contract. 00:05:00 You've got a time to do it only so much. 00:05:03 To do it. 00:05:03 Or you're a graduate. 00:05:05 You got so much time to do a couple years and you got to wrap it up and you, you don't even realize that they're loose ends, but there are, and I've had the advantage of just keep plugging away at it. 00:05:18 So the origin of Jewel Cave and its relationship to landscape scale processes. 00:05:25 How does that sound? 00:05:27 This is a uh. 00:05:28 Well, this pointer won't work, so I have to do this. 00:05:33 This is a map of kind of a 3D perspective of the Black Hills. 00:05:38 Not in great detail. It's fairly old. 00:05:42 But it shows generally how the Black Hills are shaped. 00:05:46 It's not like a big. 00:05:47 It's kind of a low bubble if. 00:05:49 Fly over it in an airplane and you get up to that that level for, well, just beyond where everything looks like. 00:05:57 Toy cars going down the road. 00:05:59 And it's kind of shocking to see how flat it really is, even with ***** peak being at the highest point. Now it's black Elk Peak, the highest point in the east of the. 00:06:13 And up in here, this is almost as high as Harney Peak. 00:06:17 Forgive me for always saying ***** peak. I haven't made that adjustment. 00:06:21 They've changed the name several years ago. 00:06:24 The Cave is found in this Paleozoic band of sedimentary rock. 00:06:31 Uh. 00:06:33 Some, but not all of this is part is called the PAJA Sapa Limestone. 00:06:38 When it goes underground, it's called the Madison Aquifer. 00:06:42 And almost everyone uses the term paasapa Limestone and Madison limestone interchangeably. 00:06:51 There's a little bit of difference, but if I switch back and forth talking about the same thing, so there's Jewel Cave right there. 00:06:58 And we're going to look at. 00:06:59 A little more carefully. 00:07:03 It's a three-dimensional maze with only one known natural entrance and that right there is sight light. 00:07:10 Why is that? 00:07:11 There's gotta be a reason for that. 00:07:14 And it used to be that people would say, well, The Cave formed three hundred million years ago after the passage was deposited, but before the sandstones up above it were deposited. 00:07:27 And then The Cave. 00:07:29 An old paleo cave formed and it was. 00:07:32 It was like random. 00:07:35 And then when he, after all, all the stuff up above was deposited, the Canyon came down and randomly intersected The Cave. 00:07:44 And that's where you got the entrance. And that's where I said it when we only knew of this much passage, you could say that. 00:07:52 But by the time we got this much passage, you could see that's not true. Here's lithograph. 00:07:58 And there's only one place right here that you can get across from a big mazy area through a tiny little opening where it goes under the Canyon, back into a big maze area. 00:08:10 Is that the opening? 00:08:11 Do you have to fit through or no? 00:08:13 What? 00:08:13 Is that the opening out here? 00:08:15 No, no, this is. 00:08:16 This is just a connection underground. The only known natural entrance is right here. 00:08:21 So is it possible that there's a lot more today that's just not been? 00:08:24 Oh yes. 00:08:26 We think we've only discovered three percent. 00:08:30 There's probably something on the order of fourteen thousand miles. 00:08:36 Remember it, but it's in a three-dimensional maze, so it's Criss crossing on top of many levels. 00:08:42 This doesn't show the whole thing. 00:08:46 There's a bunch down here, but the but what we have is only under two hundred. 00:08:49 Miles isn't underneath. 00:08:51 Four square miles. 00:08:52 So it's not. 00:08:54 Not going to Chicago or anything like that. 00:08:57 But and then this ones a little. 00:09:00 A little puzzling, but, but if you think that when that Canyon incized, it might have originally gone right up this way. 00:09:11 And it would just be a little bit better correlation. But then as it made the final incision, it was just a little bit off of that of that. 00:09:20 Most minimal area. 00:09:22 Here's the best example though. 00:09:23 Big passage. 00:09:25 Very mazzy. 00:09:27 One single craw way to get from this to this, and here we've got two. 00:09:34 Kind of three, but. 00:09:36 Big Maisie. Hardly anything big, Maisie. 00:09:40 So it's actually pretty obvious that. 00:09:45 The Cave is somehow related to the drainages. 00:09:50 It didn't form independently of the drainages, and then they came randomly. 00:09:53 If. 00:09:54 If they. 00:09:54 Truly come randomly, it'd come like through here. 00:09:57 Then you'd have dozens, maybe hundreds of openings. 00:10:01 And then this is actually very common in the whole Black Hills. Even some of the small caves. 00:10:07 Only have a single entrance. 00:10:09 And most of them were too small for people. 00:10:12 They. 00:10:13 Weren't the big. 00:10:14 Entrances like you find in the southeast US. 00:10:17 Why is that? There's something. 00:10:21 That's unique to the Black Hills, but not in Jewel Cave is just part of that. 00:10:29 The Cave is related to the topography. 00:10:33 And almost certainly the. 00:10:36 Topography. The streams, the water flow. 00:10:38 These drainages had something to do with how and where The Cave formed. 00:10:45 That makes sense. 00:10:46 I always try to make science be a kind of a slam dunk thing rather than. 00:10:51 Overloading it with complicated concepts. I mean there's value to some of these more complicated concepts, but I really believe most of what we need to know can be. 00:11:02 Discerned just by looking at the the basic kind of irrefutable concepts. 00:11:07 Can you show us on that map if you go back with? 00:11:11 With what will we be hiking at? 00:11:13 Forty five like. 00:11:15 The canyons trail. Oh, Doug. 00:11:19 Scenic Tour is right in here. 00:11:23 OK, half mile. 00:11:26 Yeah. 00:11:29 OK, now I actually probably have a better drawing, but the point of all of this is to show that all the limestone layers are dipping down this way. 00:11:41 And it forms a bowl shape. 00:11:44 So that's what the limestone is doing. Well, look at the whole cave is forming in a bowl shape and it's tilting down toward the center of the bowl. 00:11:55 So that shows us that The Cave is related to the modern day structure or shape of the of the the folding of the layers. 00:12:05 And it. 00:12:06 It couldn't have formed three hundred million years ago when everything. 00:12:10 Just flat. 00:12:12 So a relationship with today's geology could not have been created before today's rocks existed. Make sense? 00:12:26 So this is starting to point to a little bit more recent. 00:12:31 Uh. 00:12:33 For The Cave, not the original. 00:12:35 Hundred million year ago. 00:12:38 Think one of my favorite ones is this one. 00:12:42 Think of this as a layer cake. 00:12:45 Well. 00:12:45 Just think of it as a cake. 00:12:47 Think of this as the cake. This is the rocks that the cake is formed in. 00:12:54 This is the frosting. 00:12:56 This is the the cake pan because it's been bubbled up and everything 's been eroded away. 00:13:03 So this is where we expect to find all the caves. Is here never here, 'cause. There's nothing soluble to make The Cave caves. 00:13:11 And then this other stuff rests on top. Now, at one time all of this went all the way. 00:13:18 It was just flat layers and it was the uplifting that caused things to erode from the center out to this point. 00:13:25 But. 00:13:25 Here's the curious. 00:13:26 Look at where all the big caves are. 00:13:30 Run. 00:13:30 Jewel Cave is right on the edge of that where right on the edge of where the frosting is eroded away. 00:13:39 SMG cave reeds cave wind cave right on the edge, and when you look at the hundreds of caves that are out. 00:13:50 None of them is more than three hundred feet long. 00:13:53 There's no evidence of a hundred mile caves that used to be out here. 00:13:59 That shows us that basically this. 00:14:05 Cap is somehow responsible for the big caves are. 00:14:11 At one point this was over the top, but we don't find remnants of big caves, so that tells us the caves didn't form until the erosion brought this to today's configuration. 00:14:25 So with thinking that we've only found three percent. 00:14:28 Of these caves, is it possible that all of those are all connected? 00:14:33 Or not necessarily. 00:14:34 There is a potential for them to connect. 00:14:38 Umm, one of my previous assistants and I used USGS. 00:14:43 Data for the rock layers and elevations of the rock layers and elevations of the water table, and we found, and whether there were any big faults, I could cut, cut it off. 00:14:59 And we found that there was nothing to keep it. Jewel Cave and Wind Cave from connecting. 00:15:09 How many miles is it? 00:15:10 About forty miles away, twenty, twenty miles. Twenty miles. 00:15:14 So I don't have the drawing. 00:15:18 We basically this is one boundary of a Crescent. 00:15:23 Which is as far. 00:15:24 Jewel tape. 00:15:24 Go that way or any other case. 00:15:27 Then there was another one that comes down this way, which is where the tilting layers go beneath the water table. 00:15:33 Now you can have cave. 00:15:35 Beneath. 00:15:35 Water table as far as air filled caves. 00:15:40 And there's so much volume that when the pressure drops one percent, the air in The Cave expands one percent and it blows out tremendous amounts of air. When the pressure comes up, it blows it in the amount of. 00:15:55 Air is going to be proportional to the pressure change, but also proportional to. 00:15:59 The total volume of air. 00:16:01 So we were using that total volume of predicted. 00:16:06 Area we found that all passages in all caves stay in the upper two hundred fifty feet of the limestone. 00:16:13 So now we can. 00:16:14 Further narrow the control area the. 00:16:20 Potential area volume even. 00:16:24 And we. 00:16:25 We found that using a volume estimates and these other constraints, and even the fact that. 00:16:36 Passages here are much more. 00:16:39 Honeycomb, like so one hundred miles here only goes that far. 00:16:44 One hundred. 00:16:45 Here goes forty sixty. 00:16:49 So we even allowed for the differences in the The Cave density, if you will. 00:16:56 What do the flow holes tell? 00:16:58 Are those potential? 00:17:00 Undiscovered case? 00:17:01 The blowholes. 00:17:03 Yes, they somehow connect to voids underground. 00:17:08 So we put that all together and we figured out using the total volume of available limestone after we've constrained it. And then the total volume predicted by what's been surveyed so far. 00:17:22 That what's been surveyed so far would be three percent. 00:17:27 And it would be enough for these two to connect. 00:17:31 If it was only ten percent of what was needed. 00:17:36 And the volume predicted here could only go this far. 00:17:39 And the volume predicted here could only go this far that we could definitively say. 00:17:44 This probably can't. 00:17:45 But we it turned out to be almost just by coincidence. 00:17:48 Did not bias the information. 00:17:51 It turned out to be about what we what it would take. Now the only thing is. 00:17:56 Again with a diagram that I don't have for this talk. 00:18:01 Once. 00:18:03 In start moving away from the hills and gets. 00:18:07 Then it takes on kind of a regional trend and it goes circumferentially down this way. And over here it comes circumferentially around the hills to this. So down here in the hot in the. 00:18:21 That. 00:18:23 Well, it's a Hot Springs area, but there's also a particular spring. 00:18:28 It's where the underground flow converges, but there's no net movement from one side to the other. 00:18:35 So be. 00:18:35 The opposite of a surface water divide where it can go right up to. 00:18:41 Both sides of the the mountain range, but they don't connect. You just to be kind of the opposite because things are coming too, but never cross. 00:18:51 So the answer to that question is there's enough volume that they could. 00:18:56 There's a little bit of reason to think that. 00:18:58 Don't, but it's going to take a whole different kind of study to figure out if that's true and or exploration, but with is. 00:19:08 Taken. 00:19:09 Forty. Fifty. 00:19:11 Well, almost sixty. 00:19:12 Yeah. Sixty years to get that much mapped and we've only gotten a couple miles closer. 00:19:18 So we're talking generations. 00:19:19 Is this continuing? 00:19:21 Yes. 00:19:23 Yep, it was discovered in nineteen hundred. 00:19:27 Not much was done until nineteen, fifty nine and then a couple named Herb and Jan Kahn, who were climbers, were invited to go caving at Jewel Cave and fell in love with it. 00:19:40 And they kept doing it for twenty years and discovered sixty miles. 00:19:46 Then they turned it over to me and a friend of mine, and for thirty years I found I was responsible for the next seventy miles. 00:19:53 And now I've turned it over to our trip leaders. 00:19:57 Multiple trip leaders and their. 00:20:00 I don't know if all my numbers add up something like forty or fifty miles. 00:20:04 So yes, it it will continue. 00:20:07 OK, this part here. 00:20:12 Is called the mental. 00:20:14 But when we looked at it carefully, we found that it had very distinct. 00:20:19 Subunits. There's a cross bedded sandstone which is really important. 00:20:24 There's a thin bedded limestone. 00:20:27 There's a sandstone with a limestone cap, but more importantly, it's got a thick layer of shale at the base. 00:20:34 And then there are sandstone dolomite dolastones dolomite. 00:20:40 Various sandstones abraciated unit and we've got a pretty precise. 00:20:44 It does not vary significantly at all, and so instead of a big. 00:20:52 Four five hundred foot thickness. 00:20:55 Which is really hard to map. We've got distinctly different things and we can look at them and we can trace out where this is cut through to expose this. And by doing that, creating a geologic map, we can derive where things are folded and where they are. FA. 00:21:13 And we get a whole lot more understanding of what's going on. 00:21:17 So this is what we end up with. 00:21:21 This is the dual K fault. 00:21:24 You actually drove along the down through side of the dual K fault. If you came from the well. 00:21:29 You come from the east. 00:21:31 And then as it comes over here to the West, it splinters into smaller faults and then crosses Hell Canyon. 00:21:38 And then this, they all kind of dissipate. 00:21:42 All the and then up over here we don't have any significant cave. 00:21:47 The case stays in the upper two fifty feet. 00:21:50 It pinches off or gets really small where it crosses beneath canyons, so that's kind of what we're looking at. 00:21:56 Most importantly, we have a very permeable sandstone here. 00:22:01 In the bottom of this blue has shale on. 00:22:03 Of it. 00:22:04 This is the Englewood limestone, and even though there aren't cave passages down here, the bottom of it has shale. 00:22:11 We get our water from down here and when we drill a well, the water rises a hundred feet, so it's under pressure and that shale is impermeable enough to keep it under pressure. So that gives me a lot of confidence that shale keeps water from going through. 00:22:28 Also, there's less than one percent of. 00:22:33 There's like one quarter of one percent of the known cave has any water dripping water in it or even? 00:22:41 Evidence of. 00:22:43 Past dripping water. Or it might have dripped and you know, dried out. 00:22:49 That basically means that rainwater is not the source. 00:22:54 Of the water that made The Cave, which is the commonly, that's that's the base level of of. That's the starting point for almost all of. 00:23:06 Theories of how the K form either it came down from rainfall or it came from below. 00:23:13 From below. 00:23:14 Well, we've got. 00:23:15 That would keep it from. That is still keeping water from coming up from above and no passages down there anyway. 00:23:21 And the only place where we have dripping water is where that shale has been cut through. 00:23:28 So if there was water seeping into the cracks to make The Cave in the first place, some of those conduits would still be available to leak rain water in today. 00:23:42 But it's not. There is. 00:23:43 It's not quite a hundred percent relationship, but it's it's ninety nine, point seven, five percent relationship. 00:23:53 So, summarizing everything, several feet of shale at the base. 00:23:58 Uh. 00:24:00 Elusa subunit three. 00:24:02 Several feet of shale at the base of the. 00:24:05 Underlying Englewood, Ohio. 00:24:07 Overlying so you can't have water from above and you can't have water coming in from below to make The Cave less than a quarter percent of The Cave shows. Any evidence of that. 00:24:20 A dozen dripping, basically dripping through. 00:24:23 A rock that is not saturated with water. 00:24:27 And there's been no uplift structure or basically what this is saying is? 00:24:35 The way The Cave is laid out is based on the structure. 00:24:41 The uplifting and structure that has most recently happened. 00:24:45 Of you know, instead of three hundred million years ago, the evidence says more like thirty moons. 00:24:52 Music. 00:24:53 Newer and it's it's and it corresponds with today's features a structure, the contacts the exposed rocks and so on. 00:25:05 She think it happened more recently than like the Black Hills uplifts. 00:25:10 It did happen after the Black Hills uplift, OK. 00:25:14 Umm, but that puts it at at the. 00:25:18 Thirty million years ago. 00:25:19 Let me think. 00:25:22 Sixty to oh, OK. 00:25:23 So the uplift according to the literature says sixty. 00:25:28 Fold is to thirty. 00:25:30 This happened newer than thirty and there's other reasons why we get to that, but it didn't. 00:25:36 The dinosaurs are older than this cave. 00:25:39 So make if if we don't. 00:25:41 That it happened from water above or water below. 00:25:43 That's that's what I want. 00:25:46 I'm glad that you asked. Well it was. 00:25:48 Mass. 00:25:49 System I learned that in chemical engine. 00:25:54 To make to make a limestone cave, you can't have just water going into a crack and sitting there and making. 00:25:59 That bigger? 00:26:01 That water can only dissolve a little teeny bit. 00:26:04 Then it has to be moved away. 00:26:07 There's got to. 00:26:08 A way to keep moving fresh. 00:26:10 Water, not fresh water, but water that. 00:26:12 Hasn't dissolved anything. 00:26:16 To you have to move it away. 'cause. You've got to transfer that mass out of that crack. 00:26:24 Make it bigger. 00:26:25 And almost every theory that I've. 00:26:28 Examined doesn't allow for that. 00:26:32 They. 00:26:33 They don't say water just goes in, insists there, but they don't really address what is the actual mechanism. 00:26:39 Here's what we need. 00:26:40 We need to have a rock to dissolve. 00:26:43 We need to have something to dissolve the rock and it's well known that carbonic acid will dissolve. 00:26:50 Limestone. 00:26:50 A weak. 00:26:51 It might take a long time. 00:26:53 You need a transport medium, that is. 00:26:55 Also the water. 00:26:58 Something to keep moving the dissolved stuff out and you need end points. 00:27:02 Need a recharge area and a discharge. 00:27:05 Area and they've got to be aligned in a reasonable way. 00:27:10 Or just it all falls apart. 00:27:11 Just doesn't. 00:27:12 You can't just make this stuff up. 00:27:14 Got. 00:27:15 Map and see is the proposed. 00:27:20 Recharge area uphill from the discharger and then you need a continuous flow path. In other words, even with, you know, limestone itself is not very permeable. 00:27:32 So in geology, we talked about secondary permeability. 00:27:36 That's the limestone. 00:27:38 Fractured. And now that you provide that. 00:27:40 But the fractures have to be continuous. 00:27:43 If it's fractures, it has to be continuous from the recharge to the discharge or nothing 's going to happen. 00:27:50 That's always been the stumbling or the hard part. 00:27:54 But the fact that we have the very permeable sandstone. 00:28:02 Sitting on top of the less than permeable initial state of the limestone. 00:28:07 That gives the water a path to go through. 00:28:12 And so here's the dual. 00:28:14 Very simplified version of the dual cave fault and the sinclan in in Hell Canyon. 00:28:22 And these are. 00:28:23 Mostly these are different subunits of the mendeloosin. 00:28:28 But. 00:28:31 Here in Pass Creek, they've eroded down to expose that permeable sandstone. 00:28:37 And up here. 00:28:39 Canyon same thing. 00:28:41 Look at the elevations. Fifty five hundred fifty seven hundred. 00:28:46 Water can. 00:28:48 When there was active stream in right now, neither neither Canyon has active streams. 00:28:54 But when there was an active stream, water could seep into that permeable sandstone. 00:29:00 Nothing 's going to happen unless. 00:29:02 You have a lower elevation for that to now move down to and then discharge down in Lithograph Canyon and Hill Canyon, and now all the sudden. 00:29:13 Got a. 00:29:13 Way to put water in the system. 00:29:16 The recharge end to let it. 00:29:19 We got a pathway. 00:29:24 And any water running down this either of these streams will some of it's going to leak out and go downhill and discharge into the streams that were there in Hell Canyon and Lithgow Canyon at the time. And it's just gravity fed. 00:29:39 Now. 00:29:41 This is what I'm going to show you next is. 00:29:43 You know, it's not a perfect, a perfect proof of anything, but it's a very convenient observation. 00:29:50 That's where The Cave is. 00:29:53 The Cave is right there between. 00:29:57 This recharge and these discharge areas. 00:30:02 There's very likely cave up here. 00:30:04 The. 00:30:04 We don't know what we haven't discovered yet. 00:30:07 But as a first point of observation, we we have at least a partial confirmation of this idea. So it's pretty intriguing. 00:30:17 So Mike, if you look at that slide right there, right under the middle like at twelve o'clock the five, four, oh oh, the X on the red. 00:30:20 Yeah. 00:30:25 Yeah. 00:30:25 So if. 00:30:26 Go down to the last little fingers of The Cave that you see right below that. 00:30:31 Yeah. 00:30:32 Like when? 00:30:33 Get to the end of that is. 00:30:34 Just a solid wall. 00:30:37 That's where there are complications and I can't go into my easily go into my general. 00:30:42 But right here, there's a monocle and. 00:30:45 The monocline is where the rock is dipping this way, but at the monkle it dips more steeply. 00:30:53 So you have extensional. 00:30:57 Breakage. And then things in the rocks will collapse down in there. 00:31:01 OK. 00:31:03 When you're down in there, you can see there's been dissolving between those rocks. 00:31:08 So. 00:31:08 It happened when The Cave was still full. 00:31:10 For me and then there's calcite spar that formed at the end of the development of The Cave and that kind of closed up those open coating of spar that cemented them together and closed it. 00:31:24 When we were there. 00:31:25 We have strong air flow. 00:31:28 And if we're if The Cave is blowing out that day and you come out here and it's still in your face, that means that's the OR the rest of The Cave is if it was actually blowing the other way, then you might think that there are. 00:31:41 Entrances. 00:31:44 It's escaping. 00:31:46 This way and then going out those entrances. But if you are there and you still feel it in your face, that means most of the cases. 00:31:54 Here. 00:31:55 Just that it's not easy to cross. 00:31:58 And that's true. 00:31:59 I mean, not specifically because of faults, but. 00:32:04 There are fault lines through. 00:32:06 There's only it only connects here and here. 00:32:10 Not even here. 00:32:12 And it's a virtual straight line. 00:32:15 So and I can draw several of those straight lines and I can see there are places where The Cave where something 's trying to lock it off or keep it from happening. 00:32:25 But you can find that one hole you can get right on by. 00:32:30 And this one here. When you look at Zuma in, there's just one place where you cross from this through this and it's obviously a fault. 00:32:39 So it's a matter of still pushing out here until you find the one thing that comes through. Possibly you won't that, but maybe some of these things will come out here and then you'll get past OK. 00:32:55 Let's. 00:32:55 Fill in the picture a bit. 00:32:59 That is a line I'm going to show you a cross section on that line from. 00:33:05 A to a prime. 00:33:06 That's the yellow line. 00:33:10 And this is a diagram of uh. 00:33:12 Is actual data. I didn't. 00:33:15 Just randomly draw these in. 00:33:17 This is taking the data and looking at it as a cross section and you can see how it it seems to pinch off as it approaches this Canyon. 00:33:26 This is a little bit. 00:33:28 Not complete because there could be passages that come from. 00:33:32 And you know, make that a little bit more of a solid relationship, but over there, that's what's really happening. 00:33:40 There's no guesswork there. 00:33:41 The Cave gets down to two hundred and fifty feet below the top. 00:33:46 But it thins out the the thickness of The Cave system thins out and rises where it approaches the canyons. 00:33:54 And again, this pattern is. 00:33:57 True throughout the Black Hills. 00:33:59 Some pretty smoke caves. 00:34:02 So putting this all together. 00:34:07 This would be the Pass Creek area with a. 00:34:09 In it. 00:34:10 This would be the Hell Canyon area with a stream in it. 00:34:14 And umm, these would be fractures. This part here is just the pattern to show you that it's limestone, but these are the fractures. 00:34:22 Here is the bounding. 00:34:25 Shale below. 00:34:28 There's a real solid layer of shale up here, and then there's a layer that thins thickens and thins. 00:34:36 It's almost nothing but the total thickness is always forty feet. 00:34:40 So but we have water that that keeps it from coming from above. 00:34:44 It and we have obstructions that keep water that is going to come into this sandstone from these are going up here. 00:34:52 And we had the initial limestone that is not very permeable and not continuous, you know, completely continuous in its fractures. 00:35:01 I'm going to show you how valuable that that sandstone will be to actually make The Cave work. 00:35:08 So here both have cut. 00:35:10 This is cut down into the sandstone that is cut down into the sandstone. 00:35:15 And now gravity is just going to allow this stream to leak. 00:35:20 Into the sandstone, which is initially more permeable than the fractures. 00:35:28 Into that stream that will. 00:35:30 This will be a losing stream and that will be a gaining stream. 00:35:34 And now you've got your. 00:35:35 Now you've got your away to dissolve limestone and carry it away and make The Cave bigger. 00:35:42 And all the other things like. 00:35:46 And when you're when you're in this confined aquifer situation, water can come down. 00:35:53 And then go back up as long as the output is lower than the input. 00:35:58 That's just a hydrological. People know that happens. 00:36:03 And are those just normal erosion events? 00:36:05 Like allowing the water. 00:36:09 Yes. Well, whatever. Basically whatever erosion events. 00:36:17 Made Hell Canyon a steep Canyon. 00:36:20 See remember the original one was kind of a broad drainage. 00:36:27 And sometimes we can find. Well. No. No, that'll. I'm not at a place where I can tell you that 'cause. It'll get confusing. 00:36:34 But so what's happening is now it's starting to incise and once it reaches the shales. 00:36:41 And is in direct contact with that again, the Samsung 's going to take most of it, and even though it's like impermeable or it's permeable little connections between the sand grains. And it's only forty feet thick, there's actually more volume there than there is in The Cave today. 00:36:59 Sure, the passages are big. 00:37:01 Can hold huge volumes. 00:37:04 Looks complex, but it still it's still not enough volume. 00:37:08 Even equal this. 00:37:11 So that that's a little counterintuitive, but I've kind of worked through the math to do that. 00:37:16 So it's making those passages bigger. 00:37:20 And this is pretty much like quartz sandstone. 00:37:23 It's not much is it's not getting dissolved away or anything, but this is limestone and it is getting dissolved away. 00:37:33 But as time goes on. 00:37:35 This gets bigger because it's being dissolved away and the different sections begin to coalesce and we get some degree of continuity now, and this is going to take most. 00:37:46 The water. 00:37:49 But you still need this so that you have an output and see how this has cut down more deeply. 00:37:55 And you also have some of this sandstone collapsing down in to The Cave. 00:38:04 And that's the paleofil. 00:38:07 If you believe that The Cave formed three hundred million years ago, then you would believe that The Cave was already there through some different set of events. 00:38:16 The Mendeloosa Sea came in and it filled in that cave, and then The Cave as we know it today was kind of reexumed. 00:38:24 But when you actually look at these. 00:38:26 S. 00:38:27 We. 00:38:28 We don't see the remnants of an old K if we if I went down the AK Passage and I saw kind of like a partial opening all blocked with red. 00:38:39 And there was one on the other. 00:38:41 And maybe that passage. 00:38:43 So I could go. 00:38:44 The parallel passage and see the continuity. 00:38:47 Of that old original cave then I'd say textbook example. 00:38:52 Well, I've been in three quarters of this cave. 00:38:55 I've never seen a textbook in Sandy. 00:38:56 Yet so it looks to me like this stuff is simply collapsing from here and it's just sitting in place and it's whenever I give my talks, I call it Neo Phil. Paleo means old. 00:39:12 Neo means new, and if we're talking about the difference between thirty million years or less versus three hundred million years, that's an order of magnitude. 00:39:22 A legitimate difference to say to coin that idea of NEO. 00:39:27 Sure. 00:39:28 It's K, Phil. 00:39:30 But geologically, it's got to be newer. 00:39:34 Yeah. 00:39:34 About that actually, so with. 00:39:37 Is that also like part of the Middle East information? 00:39:40 That also be accurate to say that. 00:39:42 Yeah. 00:39:44 So are those sediments. 00:39:47 They were kind of deposited like. 00:39:49 One million years ago. 00:39:50 They weren't deposited long. 00:39:52 Either way, it's coming from the minalusa. 00:39:55 The question is, was it coming in by depositing into sinkholes of an already existing cave, or is it coming in when this cave forms up against it? 00:40:06 And all the there's way more evidence. But all the evidence shows seems to indicate it's concurrent. 00:40:13 Fill is collapsing in as The Cave is forming. 00:40:16 Since the settlers themselves are still old but. 00:40:19 Yes, yes. 00:40:20 Because it's like new. 00:40:20 It's the same settlements and it's the same age, but as far as being incorporated in The Cave. 00:40:21 So. 00:40:27 It's very different. 00:40:28 That. 00:40:28 Makes sense? 00:40:31 And then. 00:40:34 Once. 00:40:36 This could involve climate changes and things. 00:40:38 I'm just taking the simplest approach first. By the time that. 00:40:44 This cuts all the way through the sandstone. 00:40:46 Now, there's nothing to hold the water back, you know, to contain it. 00:40:51 So this. 00:40:51 Drains out and it dries. 00:40:54 Umm this when it was connected with an aquifer above flowed very well. 00:41:01 But now that we don't have that thing to provide the continuity, this is in the big picture. 00:41:07 Is still not very connected. 00:41:10 We've removed the weight of the water from up here. 00:41:14 That reduces the pressure. 00:41:17 In the water here and that allows carbon dioxide to degass. 00:41:23 I didn't mention earlier, but basically we start with the assumption that the water had picked up carbon dioxide from the soils and that made it a weak carbonic acid. 00:41:34 But it's like it's like pop. 00:41:38 Soda pop. You open the can and once you've released the constraint, it just bubbles off because that that dissolved dissolved carbon dioxide doesn't want to stay dissolved. It wants to get out. 00:41:51 So you've given it away to get out. 00:41:54 Now this is no longer. 00:41:58 Able to retain even what it had already dissolved. 00:42:03 So the. 00:42:03 The dissolved limestone that's in there starts to precipitate. 00:42:09 In a pretty much. 00:42:11 Standing still, body of water and that's what gives us the calcite spar. 00:42:18 That tool cave is famous for. 00:42:21 So that spar is really the lat is the termination of the development. 00:42:26 Of The Cave. 00:42:29 And then it drains. 00:42:32 I haven't. 00:42:33 I have the idea, but I haven't developed it completely. 00:42:37 These cracks always were able to maybe leak. 00:42:40 On down. 00:42:41 We don't have any place where we can see what it does at the top of this, so I am assuming that it's still, but it it's way less than the water that was moving over this way. 00:42:52 Just and so The Cave would be slowly draining out that way, doing whatever it's going to do. 00:42:59 Maybe it gets to the top of the shale and goes downhill and then comes out of springs far away. 00:43:05 But without that water in there. 00:43:08 Which provided buoyancy, it will support about forty percent of the weight of limestone. I learned something like this when I was a kid at the lake is a big rock. 00:43:19 Start picking in in the. 00:43:21 You start picking it up. It feels this heavy. 00:43:23 As soon as you get it up. 00:43:24 The air it feels sixty. 00:43:26 Or forty percent heavier. 00:43:30 So these are just basic. 00:43:32 There's lots of details to be worked out, but. 00:43:35 This works and it puts it in a real world context. 00:43:42 It's one thing to have a theory, but does your geology. 00:43:48 Here at Pass Creek and down in and Hell Canyon and having these layer does, do they actually make it work? 00:43:57 They do. 00:43:59 Everything has fit together well without any. 00:44:04 Without forcing it. 00:44:06 There. 00:44:09 I guess. 00:44:09 Some sort of event that would have caused all the water to drink rather than like. Wouldn't it kind of stay full of water over time? 00:44:18 Once the once this is cut through, I think not. 00:44:22 Because there's just nothing when it was. When the water levels up here, there was. 00:44:26 To hold. 00:44:27 Back so it could. 00:44:29 Umm this all could be in conjunction. 00:44:34 Climate changes and things like that. 00:44:36 But again, I'm trying to take the the simplest, most obvious approach first, and this is called Occam's razor. Take philosophically, always choose the simplest explanation and don't make it more complicated unless the evidence forces you to. 00:44:53 Because if you start by. 00:44:55 You know, trying, you know, dozens of different. 00:44:58 It's so easy to read something in there. It just becomes more guesswork. 00:45:02 Keep it as simple as possible. 00:45:05 But then, when the evidence forces you, you. 00:45:08 Make and don't. 00:45:09 Adapt it until the evidence forces you to. 00:45:12 So my guess, and I guess I'm asking because there is no longer. 00:45:20 Evidence of water entering anywhere. 00:45:24 Are there no stalactites or stalagmites in this case? 00:45:27 There are in that one quarter of one percent that I mentioned, yeah. 00:45:32 Where? Umm. I don't have a very clear picture here. 00:45:38 Basically where? 00:45:40 Primarily, this shale is breached. 00:45:43 That's where we would get dripping water. 00:45:46 And so it's always like on the edge of the canyons and in a couple places where there is obviously some faulting has taken place that has. 00:45:55 Reached the sale, but it's it's it's really compelling. If I showed you a. 00:46:01 With all. 00:46:01 Drip sites in. 00:46:02 Cave and corresponded with the the the breaching of that shale. It's it's very compelling. 00:46:10 So that's what you were asking. 00:46:13 Once that side dries up and there's nothing to hold the water in, you think then? 00:46:17 Just kind of naturally. 00:46:18 Drained out like. 00:46:20 Yeah, yeah. 00:46:21 Just worked its way down through. 00:46:23 So either went out or down, yeah. 00:46:25 Yeah. No it is. 00:46:28 This isn't the best diagram for this, but I have another presentation for it where I have the good the good thing. Rain water does come down through these sandstones. Then it gets intercepted by the shale. 00:46:42 And so today, all of the springs for miles and miles around are that we have are coming off the top of the. 00:46:50 Where it's exposed, I mean, I only discovered this last year that every single one of them you. 00:46:56 Know I haven't. 00:46:58 Mapped out the whole extent, but for miles and miles, every single spring is coming off of this shale. 00:47:08 So there's oh. 00:47:11 Is remember I talked about Monocle I. 00:47:14 These are blocks of sandstone in The Cave. 00:47:18 Have come down at that Monocle line so that monocline kind of broke things enough for stuff to fall through. 00:47:25 Down indicative. 00:47:27 And it's already solid rock. 00:47:29 It's cross. 00:47:30 It looks identical to rock that you see in road cuts on the West side of how. 00:47:37 That meant it was already there and it had already become rock before it went into the caves. 00:47:43 And it's way different than if The Cave already existed and then AC is sending sediments down. 00:47:49 See how that would be. 00:47:52 So this is more evidence that this is on the newer end of of geology. 00:48:00 Right after they redid the, they slightly widened the road. 00:48:04 The highway. 00:48:07 This was a fresh cut. 00:48:09 Still not there yet. 00:48:10 This this was a fresh. 00:48:12 It's harder to see now, but we can see that. 00:48:18 This is a collapse. 00:48:21 So basically The Cave was forming and it was allowing things to collapse. Then higher things collapsed, and then the farther up you go, the less room there is to collapse into. 00:48:31 So it's hard to tell here whether it ever made it to the surface, but this is basically a sinkhole. 00:48:39 Was forming. 00:48:40 Because the metal loosa was collapsing into The Cave. 00:48:44 Uh, when they were doing the redoing, the road, they broke into this. 00:48:49 This is all sandstone. 00:48:51 I went in very unstable standstill. 00:48:53 Went in. 00:48:55 I mapped it and then they filled it with concrete because it's a danger, but also it kind of curved around and went underneath the road. And if this, you know if water started rushing on there and undercut stuff in the road, that would be. 00:49:09 But see this. 00:49:09 Just the very top of that collapse. 00:49:13 Just a few feet remained and anymore collapse would basically filled it completely because Broken Rock takes up more space than solid rock. 00:49:23 OK. 00:49:26 No, I don't want it. 00:49:27 It's almost well, we still have a little bit of time. 00:49:31 So I'm going back to this. 00:49:35 And I'm. 00:49:35 I think I'm gonna look at. Yeah, OK. 00:49:41 This. 00:49:43 How did I say this? 00:49:46 There is no point lower. 00:49:52 Than this, that water can come. 00:49:55 It has to go downhill to there, so I just kind of did an outline of this cave of these cave passages. 00:50:04 Because by knowing how much area or? 00:50:09 Exposure. 00:50:11 This is how that controls how much water can go in at any given time. 00:50:16 But what's going on here is going to be that's going to control how much water can come out. 00:50:23 So really. 00:50:25 That there's your recharge. 00:50:27 Your discharge. 00:50:28 The narrower discharge is going to constrain the amount of water. 00:50:32 That can form. 00:50:33 I'm going to try to predict how fast the. 00:50:37 Can form. 00:50:38 I'm going to assume that we've got another hundred and fifty miles up here. 00:50:43 Give it. 00:50:43 Benefit of the doubt that has to be dissolved. 00:50:47 As we're forming the. 00:50:48 I can't just pick what we know. 00:50:50 So I'm going to assume that it's everywhere in here. To be fair to this assessment of how long it would take for The Cave to form. 00:50:58 Oh, I thought I took this. 00:50:59 We're not going to go into this right now. 00:51:03 Oh. 00:51:07 I think I took out something that I did not want to take out. 00:51:13 Yeah, I took out the wrong thing. 00:51:14 If you just explain a little bit. 00:51:18 OK. 00:51:19 So this ends up being a what do you call that shape? 00:51:25 No, it's four sided. 00:51:28 This. 00:51:28 Kind of like a trapezoidal thing. 00:51:31 You could draw it in three dimensions. 00:51:33 Can apply. 00:51:36 A hydrologic formula to it. 00:51:39 The. 00:51:39 The amount of water that's going to flow over any given amount of time is going to be dependent on the permeability of the rock. 00:51:48 It's dependent on the elevation difference. The steeper it is, the faster it will go, and it's going to. 00:51:57 And it's going to be constrained by the area where it can come out at that at that narrow end. And based on that, I was able to calculate. 00:52:10 Then I had another diagram. 00:52:13 That would tell me making some basic assumptions of temperature. 00:52:19 And pressure and we we look at this, this is all happening in recent geology. 00:52:24 So there's really no likelihood that it this formed when it was a thousand feet underground. 00:52:29 So I could make assumptions about. 00:52:32 The temperature in particular. 00:52:37 And estimate the amount of. 00:52:41 Of limestone that would resolved per liter. 00:52:46 And then I took the number of liters for all of this, plus the assumed amount. 00:52:51 And divide it into it and got a time that it would just a minimum amount. Basic assumption estimate of what it would take to dissolve out that caveat. 00:53:03 A. 00:53:03 Hundred ten. 00:53:03 Million years. 00:53:06 One point one million years. 00:53:09 That and no. 00:53:11 No monkeying with the data or anything. 00:53:14 That was an eye opener. 00:53:19 So it would only take that we have one radiometric date on the spar. 00:53:24 Remember, the spar was coming like the termination of cave development, because now all the water is gone. 00:53:30 Can't. 00:53:31 It's not coming. 00:53:32 It's not going to make them more sparse. 00:53:34 So that's been dated at about eleven. 00:53:39 Let me. 00:53:39 Yeah, about eleven million years. 00:53:42 So The Cave could. 00:53:43 Stopped forming eleven million years ago and started forming only a million years before that. 00:53:51 So that makes it geologically very recent. 00:53:55 There are lots of other things. 00:53:56 Three or four more talks. 00:54:00 To support this idea, and I apologize. 00:54:02 I deleted the wrong sides. 00:54:06 Yeah, this is complicated. 00:54:10 Basically all all that what what it says is. 00:54:14 This method of. 00:54:16 Dissolving out The Cave. 00:54:19 Would be much more effective. 00:54:21 Then where it's coming through this blanket and doing this, then most of the traditional guesthouse of how fast it would dissolve. 00:54:33 But it's too complicated for this talk. 00:54:35 So the question is, since carbon dioxide is the the thing that makes it acidic. 00:54:44 Is there enough carbon dioxide to make this happen? 00:54:49 And. 00:54:52 Perhaps if microbes entering the sandstone aquifer encounter a food source like organic carbon in shale and clay layers? 00:55:02 Basically, they metabolize the shale and they convert it to carbon dioxide. 00:55:09 That's one of the biggest problems with the whole carbon dioxide thing. If it's coming from soils, then why? 00:55:14 Then it should be most acidic here and it should just pinch off as it goes in the Jewel cave is big and small and big and small. 00:55:22 But so is there enough? 00:55:25 Carbon dioxide to make it happen this way, and the answer is. 00:55:32 We could be generating way more common dioxide than we would ever get right at the surface by the microbes metabolizing the the free carbon in the cells and just saturating this whole thing with carbon dioxide. 00:55:47 And that way you can get it way down underneath and still strong enough to. 00:55:52 Big passages. 00:56:03 Cane plant material and stuff like that. 00:56:06 No, I'm pretty sure I do know that there have been studies on some of the coloring that a lot of times like stalactites will be red because there's iron. 00:56:19 But there are times when organic acids, not actual material but organic acids can Causeway the same chloration and vice versa, just because it has something in there doesn't mean it's necessarily going to be that color. 00:56:34 It's a little more. 00:56:36 A little more complicated than that, and we're getting into fine degrees of geochemistry that I don't think anyone has sorted out to this point. 00:56:45 More of. 00:56:47 Take samples you test and then you see that this is either from that or from the other thing. 00:56:52 It's not good enough that you can actually predict. 00:56:55 OK, now. 00:56:58 That's I asked that question of Hazel Martin and Penny Boston. 00:57:03 Hazel Barton is a well known caver who has gotten very deep into. 00:57:09 Studying extremophiles especially. 00:57:14 Umm. 00:57:16 Microbes. 00:57:19 They have very unusual. 00:57:22 Qualities that you were unexpected. 00:57:25 Penny Boston was a caver and a geologist, and I don't know if she still is, but for a time she was head of Nasas. 00:57:35 Exo biology program trying to figure out what you would need to decide whether there was. 00:57:41 Life on Mars? 00:57:43 So these are people that know what they're talking about. 00:57:46 Is not a big scientific I didn't. 00:57:48 You know, they're just. 00:57:49 I'm just asking them is this a possibility or is it completely not possible? 00:57:57 And remember, here's here's our shale that is right there between the top of the well, there's sale up here, But there's also sale right here. 00:58:07 Is the sandstone at one time it was an aquifer and it had this intermittent shale in here. 00:58:13 So it was an intimate contact with shale. 00:58:16 And then so Hazel said. This is a quote from something she wrote. 00:58:21 Microorganisms change the local geochemistry and can dramatically accelerate spleenesis and even lead the K formation in geochemical environments that would otherwise not be conducive to dissolution. 00:58:35 Like a quartzite sand cave, which is not eroded out, it's been dissolved out. 00:58:41 Quartz does not normally dissolve, but those those microbes. 00:58:47 Catalyze. 00:58:51 OK. 00:58:53 I got a little technical but I. 00:58:56 Think you would? 00:58:57 What's getting the idea? 00:58:59 What kind of question is? 00:59:02 In the years that you've been working on this in those predecessors that were working on it, have there been any earthquakes in this area that can affect the caves and wood, an earthquake? 00:59:15 Well, I mean, at one point with all the fracturing and the faulting, you know, during the uplift of the hills and and maybe in the aftermath of that in many years past. 00:59:27 You know, eons past. Yes. Today I've been in The Cave and both here in Edwin Cave. And when there were earthquakes. 00:59:38 Then killed thing. What happens is though somehow that earthquake is, I believe is setting up like it's low, low, low frequency you. 00:59:48 Barely hear it. 00:59:49 It's setting up. 00:59:51 Pulses. 00:59:54 In The Cave air and you can hear it. 00:59:58 There's a place where we were surveying and I thought I heard something. You. 01:00:03 Know for a couple. 01:00:03 Seconds. But I thought it was my. 01:00:06 Like a low rumble. And just as I spoke up, we all spoke up at the same time and said. 01:00:13 Did you hear that? 01:00:14 OK. And then we were like wild. 01:00:17 Did something collapse, or would we feel a surge of air? 01:00:21 There be dust. 01:00:22 We trapped. 01:00:23 Nothing. We came out. Everything is the. 01:00:26 But I at the time the School of Mines had a seismograph. 01:00:29 And we verified. 01:00:30 With them that there was a tremor, a four point, something tremor halfway between here and. 01:00:43 Some near igloo. 01:00:45 Umm. 01:00:47 I'm spacing it out. Oh anyway. 01:00:51 Down there, down South and it was that exact same time. 01:00:56 Wow. 01:00:57 That no one felt it on the surface either. 01:01:00 So today, it's not in for a long time and you know for thousands of years at least. 01:01:08 There's not been anything that. 01:01:09 Make any difference?
Learn how Jewel Cave formed and what makes the cave so unique with Ranger Mike!