Chris Bolhuis: [00:00:00] How we doing? Dr. Reimink? You're just waiting for me. Alright. Hey, how about if I go, okay, Jesse, how about that?

Dr. Jesse Reimink: How about if you go first this time?

Chris Bolhuis: I start us off? All right, we can do that. Well, We're talking today about Midway and Lower Geyser Basin.

Dr. Jesse Reimink: But really Chris, I mean the marquee thing here is Grand Prismatic spring. I mean, this is what people come to this location for. This is, just [00:00:30] like, you know, first round Hall of Famer. I mean, this is, everybody comes to Yellowstone for Old Faithful and Grand Prismatic. I mean, those are the two big, big, big dogs, right? And image number one shows an example of of just kind of why this is like, it is a beautiful, stunning feature. But this episode we're gonna do an overview of the basins around it. There's a lot of features around Grand Prismatic. There's a lot of cool Geology around there. There's some cool stuff about Grand Prismatic as well. So we're gonna hit all of that. We're gonna work through Midway Geyser [00:01:00] Basin. We're gonna talk about Grand Prismatic. We're gonna do a little review of the waters that we've been talking about for the last couple chapters. And, we're focusing in on this region here. And we're gonna end up talking about the lower Geyser Basin. And so image number two shows you geographically where we are in the park, what the features we're talking about. And remember, Chris, I always get confused by this one - Lower Geyser Basin is actually up on the map here, so that's always quite confusing. Just remember that one when you're driving around.

Chris Bolhuis: That's right. Just again, a reminder. They're [00:01:30] named what they're named based upon their elevation. So the Upper Geyser basin, which is further south, has a higher elevation than the Lower Geyser basin, which is further north. So that's why they're named what they're named. Jesse, let's start off with the Midway Geyser Basin. Okay. And I wanna be clear on this too, that there technically is no midway. It's more of a colloquial term. It's a part of the Lower Geyser Basin

Dr. Jesse Reimink: Don’t be so mean to midway. Let it exist. Let Midway Geyser Basin exist, man. I mean,[00:02:00]

Chris Bolhuis: Yeah, well, it, it's technically a part of Lower Geyser Basin, but it is separated geographically from it, and so it's in between the upper and the lower, and hence the name Midway. It just kind of stuck and it's kind of held on, and now they actually acknowledge it with parking lots and signs and so on. So it is, it's a thing - Midway Geyser Basin is a thing.

Dr. Jesse Reimink: and we've talked about some of the Geology and geochemistry of this region before. It's kind of similar to the old faithful area, this upper geyser basin, Old Faithful area, what we're talking about here [00:02:30] in Midway Geyser and Lower Geyser Basin, kind of similar alkaline chloride waters. Review that for us again. What are we talking about? Alkaline chloride.

Chris Bolhuis: Sure. You know, there are three kinds of hydrothermal features that are common in Yellowstone. The alkaline chloride, which is the upper geyser basin, old faithful, and here midway and lower. You have the carbonate waters like Mammoth, they form these travertine or limestone terraces. And then you have the acid sulfate features, which form mud pots and [00:03:00] fumaroles. Those are the three kinds. The alkaline chloride waters that we have here. And at Old Faithful you have these super heated groundwater that's circulating. And then what it does is it dissolves silica, which is quartz. It's SiO2. Well, what this does chemically is it makes the water basic. Which means it has a higher pH. Okay, now this gets complicated though because you have this gas that's rising up from the magma chamber, carbon dioxide, and hydrogen sulfide. These gases make the [00:03:30] water acidic. And so you have two things going on, but as it rises to the surface, the water starts to fizz. It degasses, which then turns the water back to being basic because of the dissolving of the silica that happened deep down. So it comes out. It's not acidic when a lot of people think it is. It's actually not. It's very hot, but it's not an acid. So there we go. How'd I do?

Dr. Jesse Reimink: Yeah, that was great. Excellent review. And that's gonna actually frame us, because we talked about, the last couple [00:04:00] chapters, we've talked about how there's a lot of fine scale, local scale variation in this stuff, right? And that's really well represented here. So what we're gonna cover is a little bit of a tour of the geology and again, the geochemistry and some of the biogeochemistry of these features because you can see all sorts of things. You can see mud pots, you can see springs, you can see fumaroles, you can see geysers. There's a lot of features you can see in this region. And so that description you just made - the differences in the waters, they happen at a big scale [00:04:30] across Yellowstone, and then they also happen at a very local scale in any particular Geyser basin or any given boardwalk that you might choose to take. So Chris, I

Chris Bolhuis: So we're gonna get into some of the smalls, right? But basically the geology's the same. And so what this is really about is, hey, go here and don't miss these features. That's kind of what this chapter's all about.

Dr. Jesse Reimink: and also think about these things while you're walking around, while you're looking at these features. Think about these things. So I think Chris, for me, I'd love [00:05:00] to just start with Grand Prismatic image number three shows this great view. I mean, there are so many ways to see this thing. We're gonna talk about that. But it is such a hallmark feature of Yellowstone and there's a reason it is on the postcards everywhere. It is stunningly beautiful. So what's going on with the, the colors here? Like I. I don't know, Chris, it's arguably the most beautiful hot spring in the world. Right?

Chris Bolhuis: Oh, I don't think there's any argument to it at all. This is undoubtedly the most beautiful [00:05:30] hot spring on the planet. It is, it's amazing. Uh, it's jaw dropping. It, it lives up to the reputation. It is everything you, if you go there, you will not be let down. You will not be disappointed. I promise. The colors pop, especially when the sun comes out. So hopefully you pick a sunny day, hit it and it's just absolutely amazing. Um, Well, yeah. Do you want to talk about the colors a little bit? We have here look, it's the largest hot springing in North America so that makes it stand out. And then also, The [00:06:00] colors make it stand out. So a brief review, and if you go to image number four in your stack, this is a, a really cool gif that we made that shows the different colors. It gives you the name of the thermophiles that live in that. And the thermophiles, not only do they form the sinter mats, but they also have beautiful colors that are associated with them.

Dr. Jesse Reimink: Chris, just a real quick reminder, they're thermophiles. These are. Biological creatures. These are bacteria that are [00:06:30] living in these extreme environments. So thermophile or extremophile are things that live in extreme or hot environments here, and so that's what we're talking about here. And the colors really indicate which species is dominant, or which, you know, assembly of species are dominant in a particular zone and which species are in a zone, is dependent upon: A - the temperature of the water and B - the pH of the water. And so as we move from the inside out, we can see this radial change in the temperature and [00:07:00] pH of the water, and therefore the species of thermo or extremophiles that are living there, which give it the color. I mean, it's a really, really cool example of the interaction or really the control Chris, if, if I say the control that Geology has on biology, I mean, Geology defines everything about the biology, right?

Chris Bolhuis: That's much better. I was gonna jump on you about that. One thing that I think is worth pointing out too, the blue in the center, this really gorgeous blue color, it's very hot water, and it's blue because it has [00:07:30] tiny suspended particles of silica. It's called colloidal suspension. We'll talk about that a little bit more in the next chapter when we get into Norris Geyser Basin. But that's what the blue is from. The blue is actually not from extremophiles.

Dr. Jesse Reimink: Chris, where do we get silica from? Well, we're surrounded by Rhyolite. It's Yellowstone. There's a lot of Rhyolite around very high silica rock. That's where the silica is ultimately coming from. And in 1994, Chris, geologist Rich Hutchinson actually had a small rowboat, which was fiberglass coated [00:08:00] plywood and, and rode out and measured the center of the spring. And so Grand Prismatic is 121 feet deep, which astonished me. I always, when I look at this thing, I always kind of think it's really wide and probably really shallow. Like I have this view in my head of like a dinner plate kind of structure where it's really wide and really shallow, but actually this thing's pretty deep. 121 feet deep. It's a beast.

Chris Bolhuis: Hutchinson is my hero, actually. Um, I, I have a, I have a lot of admiration [00:08:30] for anybody that's gonna go out in the middle of a hot spring. Not only a hot spring, the biggest hot spring in North America. I mean this, that's unbelievable feat. Yeah, he, he developed a bit of a reputation, um, for, for that kind of stuff. So, well, alright. Grand Prismatic - amazing. Don't miss it. But while you're there, there are a few other things you better check out. Image number five shows these, Excelsior Geyser, it is just north and just east of Grand Prismatic. Had huge eruptions [00:09:00] in the 1880s, and these eruptions were over 300 feet high. And this is a fountain type geyser and a fountain type geyser is the one that have the big pools at the top, you know. And, actually, when you look at Excelsior, and the boardwalk weaves you right up nice and close to it. When you look at this, you can actually see the visible crater from the eruptions that happened in the 1880s. It's very, very steep sided rim to this, you know, now it's a hot spring.

Dr. Jesse Reimink: So 300 feet, that's about the width of Grand Prismatic. So if [00:09:30] you took Grand Prismatic and stood it on end, that's how high that water's going. I mean, that's a violent eruption from a geyser and these big eruptions like ripped out this sinter lining, created a more free flowing pathway. And we've talked about this a lot before. These things change, these hydrothermal features are constantly changing, constantly evolving.

Chris Bolhuis: That's right. I'm gonna interrupt you a second. So the sinter is key to geysers and hot springs, right? It's particularly key to, to geysers because it provides this pressure tight system on the [00:10:00] lining

of the throat or the vents leading to the surface. That's what you have to have for geysers. Well, this thing erupted so violently just ripped it right out. It's kind of like if you get sick, you know, you get this kind of phlegm in your chest, you know, and we end up coughing and that that violent coughing reflex rips up the stuff that's in our throat it went back to be in a hot spring because it ripped the lining out. So over time, Excelsior may turn back into a geyser.

Dr. Jesse Reimink: [00:10:30] Yeah. And how does it turn back into a geyser, Chris? Well, that phlegm kind of builds up and there are 6 million gallons of water per day flowing to the surface in this hot spring. So that's a lot of water containing a lot of silica and other constituent elements that will make up that sinter. So there is sinter being precipitated on the edges of this thing right now, and eventually, it could become a geyser again, right? It could constrict that throat down such that it needs to cough to clear itself out. And so again, these things evolve. They change back and forth. [00:11:00] The only way these things really die is if they run outta water. That's like death for any hydrothermal feature, cuz there's hydro in the name, you need to have water in there. That's the only way they kind of die, otherwise they're just changing kind of back and forth and periodically oscillating back and forth over long time scales. So, and again, just image number five is a great image, kind of shows you that loop of the boardwalk and things you can see. And as you'll notice, There's two other features in here. Grand Prismatic, the big one, what people go for, but you gotta check out these other ones. Turquoise Pool and Opal [00:11:30] Pool, and we kinda lump those together, Chris, what makes them interesting and what do you point out when you're bringing students along this boardwalk here?

Chris Bolhuis: uh, they're just different colors. They're, they don't look like Excelsior and Grand Prismatic, and I, I think they're just - Hey, you know what, you're right there because the boardwalk weaves you right in and out of that stuff. And they're just, unique looking hot springs, and they're pretty. They're worth a look.

Dr. Jesse Reimink: And they have different colors because the water temperature is different. The pH is different. The organisms living in there are different, right? And so these are not that far away. They're a couple hundred feet away in very, very different environments, which [00:12:00] again, shows that Geology controls the biology. But, but I digress. Uh,

Chris Bolhuis: That's right. So before we leave, Midway, I want to hit make a couple of other notes. Okay. One is, so to the north of the basin, you can't miss 'em. You'll see these two rounded hills right next to each other. They are called the twin buttes. And you'll see these on all the signs around the boardwalks too, pointing out these hills. They're made of sand and gravel. And these are glacial [00:12:30] deposits, which is a really nice shout out to our chapter two, the 30,000 foot View of Yellowstone when we talked about one of the last pieces of the history of Yellowstone, the geologic history, the glaciers. And these hills are glacial deposits of sand and gravel. They're, they're just kind of a landmark.

Dr. Jesse Reimink: Chris, I think, uh, for me, I grew up in Michigan where you live still, and that's heavily glaciated terrain. There's hills of sand and gravel all over the place. There's all sorts of glacial features. I now live in Pennsylvania, which is un-glaciated. And so when I go back here, get to [00:13:00] look at these twin buttes, and I get to sort of feel like home a little bit. There's glacial features, there's glacial landforms right nearby, and a great reminder of that 30,000 foot view. You're right. So, another thing you definitely gotta check out in this area is Fairy Falls. That's image number six in your stack. It's a 200 foot waterfall, and I, I love the name. I Mean, the naming system in Yellowstone is just beautiful and self descriptive. Fairy Falls. It's like this fairy trail of water. It's not a huge waterfall, not a lot of water coming over the edge of it, but it's a very high [00:13:30] waterfall. And so, the hike is pretty flat and easy and, uh, once you get out there, continue north, it's about five and a half miles round trip. and there is a, a little detour from Fairy Falls to another geyser, Imperial Geyser, which I think, Chris, you love this one if memory serves right. Is that, is that correct?

Chris Bolhuis: I love it because it's very active, at least, well, you know, when I'm there, it has been very active. Remember, things change all the time in Yellowstone. It's very active though, and it's secluded. You're not [00:14:00] gonna be around a lot of people, and, I, I love it for that. So and so I, I highly recommend Fairy Falls and and then take that little detour out to Imperial Geyser, not to be missed.

Dr. Jesse Reimink: Okay, Chris, so I think, does that cover it for Midway Geyser Basin, which really isn't technically, you know, its own thing, but does that cover it? Should we move on to the Lower Geyser Basin

Chris Bolhuis: I think so let's move on to the lower proper. Okay.

Dr. Jesse Reimink: Yeah, lower proper, which is confusingly to the north. I still can't, you know, it still throws me off. We're going up [00:14:30] on the map, but it's Lower Geyer Basin anyway.

Chris Bolhuis: That's true. What is not to be missed at Lower Geyser Basin? I wanna throw you back when we talked about the Upper Geyser Basin and Old Faithful. I said, listen, if you don't have a lot of time, here's what you need to do. I said, watch Old Faithful erupt and then get back in your car and go to the Lower Geyser Basin. And I want to talk about why it seems like a funny kind of thing, but the Lower Geyser Basin is the largest [00:15:00] geyser basin in the park. I mean, this is a huge area, right? It's 18 square miles. But the thing is, is it has it all. It has mud pots, it has fumaroles, hot springs, and very active geysers. So best bang for your buck is probably gonna be here if you're limited on time.

Dr. Jesse Reimink: That's a great recommendation and we can see all sorts of stuff here like you just said, and, and let's just review again really briefly, kind of why you see different types of things in different environments and the acid sulfate thermal [00:15:30] features, which are fumaroles and mud pots. Really, mud pots are the main one. That is, we talked about that last chapter. What controls that, but this is a limited amount of water. It's acidic water, and so the acid that is there is great at dissolving rock. So it dissolves rock. You get rock plus a little bit of water and you get mud. And so the reason that the waters are different is because they're taking different paths to the surface. It all kind of starts out very similar at depth, and the water changes chemistry and composition as it makes its way to the surface. And at Lower Geyser [00:16:00] Basin, there's a lot of different pathways to get to the surface, which means the waters end up being quite different - even in a a single geyser basin. Chris, the topography, can you just review the topography again, like the topographic control on these things? Because I think, again, like we talked about before in last chapter, it's really prevalent here. Or it's, it's very obvious maybe is the way to phrase it.

Chris Bolhuis: Yeah, if you're higher up like on a hillside or something like that, you're further away from the groundwater beneath the surface. And so that's where you're gonna tend to get the fumaroles, and mud [00:16:30] pots. And so, yeah, Lower Geyser Basin - some of the easiest to access mud pots or mud volcanoes are here. It's called Fountain Paint Pots. They're amazing. Uh, we actually had an image of them, in our last chapter. Uh, these things are pretty cool and not to be missed.

Dr. Jesse Reimink: So fun to watch. So fun to watch.

Chris Bolhuis: Yeah, that's right. And that's right. In fact, you alluded also to fumaroles, and I want to turn everybody to image number seven in your stack. This is about as good of, it's so good. [00:17:00] This example of a fumarole is about as good as you're ever gonna see. It's just violently hissing out of the ground. It's a very, very cool feature. And so there you go. You see in close proximity, then mud pots, fumaroles. But you also get to see geysers and hot springs here. Um, and so let's talk a little bit about that.

Dr. Jesse Reimink: Before we do that, Chris, let me just interrupt real quick. Fumaroles are really fun to have around I think they're kind of fun to watch. Like steam coming out, but they always do this kind of hissing noise, right? Yeah. Cuz they're hissing. [00:17:30] Don't you know? You know what I mean? It's kind of like this weird background noise that after you know, an hour in Yellowstone, you kinda get used to it and you don't hear it anymore. But every once in a while you'll be walking around and you'll just hear this kind of hissing, steaming like you, you can close your eyes and kind of - you can sense that you're on top of a volcano because of all this kind of hissing, steaming that's going on. That's what I mean. They're kind of fun to have around. I think fumaroles are just great fun.

Chris Bolhuis: I'm gonna interject something off topic, because you're right. Fumaroles are awesome. I'm on Mount Shasta. I need water. I don't have water, so I [00:18:00] take snow and I cram it in my, my green, uh, metallic liberty bottle, you know, and I set it on a fumarole and it just melted it just like that. It was so fast. Very, very cool thing.

Dr. Jesse Reimink: They're great and they're, they are, you know, you're in a hot area when there's fumaroles coming around the ground is literally steaming.

Chris Bolhuis: It's volcanic. That's right. okay. Real quick and we'll wrap this up, Jesse, but there are a lot of geysers here that have very short intervals. So you're guaranteed if you spend just a little bit of time here in the Lower Geyser [00:18:30] Basin, you're guaranteed to see some geysers erupting. Once again, it has it all. It's a very, very cool thermal place in Yellowstone.

Dr. Jesse Reimink: An image number eight shows Fountain Geyser, which is again, just a very appropriately named geyser. It just looks like a fountain. It's kind of throwing up large volumes of water, much like, you know, a fountain in a city center will be doing. It's beautiful. These are really fun to watch. I find these kind of fountain style geysers. I find them. A little bit confusing because there's so much steam and there's so much water. It's kind of hard to tell the difference between the [00:19:00] two. But actually if you, if the wind is blowing and it blows the steam away, you can really see the incredible volume of water that these things are kind of bubbling up or spitting up in the air. They're, they're really cool style of geyser,

Chris Bolhuis: Very good point. And Excelsior at back at Midway - that brings about 6 million gallons of water to the surface every day. it's an amazing amount of water. Absolutely. And you just made me think of that.

Dr. Jesse Reimink: so, Chris, that's a good segue into the FAQ because we're talking about these [00:19:30] premier features and if we go back up to Midway Geyser Basin where we have Excelsior and we have Opal Pool and we have Grand Prismatic. I think one common thing, and and if you're listening to this and you're planning a trip, Probably a question you're asking is what's the best way to view Grand Prismatic? And there's several, but, we'll talk about a few of them I think Chris here. Like when you're going there, if it's just you and Jenny, or if you have a whole bunch of people with you, a bigger group, how do you view it? How do you think about viewing Grand Prismatic?

Chris Bolhuis: Okay. I, I think of three things, or three ways or three [00:20:00] places. One, the boardwalk brings you right up close. You get to smell it, you get to see it up close and personal. That's okay. To me, the best way is a place called Grand Charismatic Spring Overlook, and this is easiest to access from the Fairy Falls Trailhead parking area. It's just south of Midway Geyser Basin parking. So, what you do is you, from the parking lot, it's about a 0.8 mile walk. It's flat, it's on a dirt path. It's easy. Okay? So it's gonna be [00:20:30] 1.6 miles round trip, and you'll see a little side trail, a little spur that goes up to the left on top of a lava flow. And you get to look at down then on Grand Prismatic and really appreciate the colors of this, this amazing hot spring. So that's my favorite.

Dr. Jesse Reimink: I think Chris the, the third way to view grand prismatic is really the view presented in image number three in our stack here. And this is Midway Bluff and it's just south of the Midway guys are parking lot, and it's actually kind of across the street, if I'm not [00:21:00] mistaken. And, this is a little bit of a harder, short, hard hike. Right.

Chris Bolhuis: Yes, it is. It's short. It's steep, but it's worth it. A hundred percent. Now, I do want to throw this out there too, that the park sometimes closes these little spurs off periodically, and they do that for a reason, and those reasons can vary. So just, it happens to be closed off, find a legal different way. If they have the bluff closed off, then go to Grand Prismatic Spring overlook, you know? But don't just [00:21:30] ignore the signs and go up anyway. One, it's not the right thing to do. Two, you can get ticketed and they don't really mess around in Yellowstone as they shouldn’t.

Dr. Jesse Reimink: Yeah, Great point, Chris. Well, hey, I think that's a wrap for Grand Prismatic in the Midway and Lower Geyser Basins. Yeah.

Chris Bolhuis: I think so.

Dr. Jesse Reimink: Okay, great. Have fun. Get out there and enjoy it.

Chris Bolhuis: That's right. Cheers.