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Thermal Features and the Upper Geyser Basin
by George Heinz
Presented Live Aug. 13, 2009
Park Ranger George Heinz: Good afternoon ladies and gentlemen, we’ve got a live program starting here from Geyser Hill in Yellowstone National Park here in just a couple of minutes. We’re across the river from the Old Faithful Geyser and the Old Faithful Inn. We are going to let our camera do a little swing around the basin just to give you an idea of where we are standing and we’ll be back with you in just a minute or two. So, stay tuned.
You can see, we’re right next to the Lion Group over here on Geyser Hill. There are about 40 geysers on this hill. We will get more in to those particular things here in just a bit. You see a little of the Firehole River here. Then, that’s Castle Geyser out there, maybe the oldest geyser in the park. You get a little view of the lower store; that’s the oldest building still in use here, 1897. You get a little view of the Old Faithful Inn; it’s been open and operating since 1904. There’s a shot of our new visitor center that’s going to open next year. You’ve got Old Faithful Geyser and you can see the people waiting. The Old Faithful Lodge and then we’re swinging back around and the camera is showing you Geyser Hill again. So, stay tuned.
Welcome to our program, my name is Ranger George Heinz and I’m a ranger here in Yellowstone National Park. It’s just a pleasure; it’s a great day here. It’s sort of windy, maybe in the upper 60s or lower 70s, and it’s just a beautiful day in Yellowstone. So, I know a lot of you all are wishing you were out here watching these geysers. But, this is an amazing place and I hope you get to visit soon.
When Yellowstone became the world’s first National Park on March 1st, 1872, it was by an act of Congress, Ulysses S. Grant was President. The park is about 2.2 million acres or 3472 square miles in size today. That’s about the size of Rhode Island and Delaware put together or 2/3rd the size of the state of Connecticut. This is a great-big place. Yellowstone was first set aside because of the geology, because of these thermal features.
As a ranger, when you are working here, we often get asked, “why do you have geysers here?” “Why are there hot springs here? Why do you have them and I don’t have them in my back yard?
I usually try to answer that question by giving that person another question. I ask them, “Well, what is Yellowstone?”
The answer to that is, it’s a volcano. And, Yellowstone is just not just any volcano, it’s one of the world’s largest volcanoes, we believe. But, it’s different than most of the volcanoes you find, at least in the continental United States. So, if you know a little about the geography of the U.S. and I ask you, “Where do you find most of the volcanoes?
You would probably tell me the west coast. Those volcanoes were formed a little differently than the Yellowstone volcano. We think our volcano formed more like the Hawaiian chain of volcanoes. Up and down the west coast, you have the ocean floor, which is made-up of extrusive igneous rock, basically basalt on the Pacific Ocean floor.
The continent, you know, the North American continent is made-up of intrusive igneous rock, basically granite. And granite cools very slowly, over 10s of thousands of years. It can form impurities, so it’s lighter than that extrusive igneous rock. You have the heavy ocean floor and the lighter continent banging in to each other all up and down the west coast. Well, that heavy ocean floor gets subducted below the continent and that’s called a subduction zone. That’s where you find most of the volcanoes in our country. You have Mount Rainier, Mount Hood, Mount Shasta, Mount Saint Helens and Mount Lassen, there’s a whole list, probably 50 or so active volcanoes in North America. Yellowstone is just one of them and it’s a big one.
If we look at why Yellowstone was formed, I’m going to pull out this diagram here. We call this the hot-spot track. Over here on this far end, you far left end, is the west coast of our country. This is Oregon and this is Nevada. About 16 million years ago, we believe that the hot-spot that is forming the Yellowstone volcano was below that part of our country. So, we have maybe a hundred calderas between here and the west coast. This orange dot is just showing you a few of those. Just looking at this diagram, you would assume that the hot-spot was moving, the hot-spot is not moving; the continent is moving. North America flows at an inch or two a year in a southwest direction. The continent has flowed over this hot-spot.
Today, we believe that the hot-spot is below Yellowstone. We’ve had 3 great-big eruptions here that formed calderas and some smaller calderas as well. This red circle here, sort of an oblong deal, but it represents an eruption that happened about 2.1 million years ago. That eruption was about 6,000 times bigger than the eruption of Mount Saint Helens back in 1980. And then, we had an eruption a little bit smaller about 1.2 million years ago. And then, this larger yellow dot is what we consider today’s Yellowstone caldera. That eruption happened about 640,000 years ago. What happens with a caldera is, it bubbles-up and little cracks and fissures form in the side and lava starts to pour out and eventually that floor of that caldera sinks. So, it’s basically a sunken volcanic crater. If we pull out a map of Yellowstone; this is the map you would get at the gate when you visit the park. We’ve outlined the caldera. The caldera is about 30 by 45 miles across. This is a great-big crater. We get people that ask all the time, “I’ve spent the last few days driving around Yellowstone and I see the thermal features, I see the steam, but where is the volcanic crater?
That’s because lava flows continued and lava filled-in much of that caldera. The last lava to flow out onto Yellowstone’s surface was about 70,000 years ago and it was on an area called the Pitchstone Plateau. We’ve had some other steam explosions here about 180,000 years ago and the West Thumb of Yellowstone Lake was formed. Basically, that’s why we have thermal features; we’re on a giant volcano.
I’ve just been informed that Beehive Geyser’s indicator is going, so we’ll keep an eye on it. It’s one of the larger geysers in the world. It only erupts once or twice a day. So, we’ll keep an eye on it; it has a little geyser that starts erupting about 10 or 15 minutes before the big eruption. We’ll keep an eye on it and you’ll definitely get to this, because we’ll still be talking. When it starts going, we’ll just shift the camera that way. Stay tuned for an eruption of Beehive.
I’ll just bend over here for a second. What’s left here, since this is a volcano, after all the eruptions and the lava flows are 4 different types of thermal features. We have hot springs, geysers, mudpots and fumaroles. Some of them you can find all over, you can find hot springs all over as you drive around the west. You’ll see Lava Hot Springs, Chico Hot Springs and Fairmont Hot Springs; there not rare, but some of these features are pretty rare.
One of the rarest is a mudpot. This is a picture of the Fountain Paint Pot, down in the Lower Geyser Basin. One way mudpots can be formed is if you have a hot spring that doesn’t have a runoff channel, there’s really no where for that water to go once it gets to the surface, except to evaporate. There is some little heat loving chemotrophic microorganisms that live in that acidic water. They live off of hydrogen sulfide and they convert that hydrogen sulfide into sulfuric acid and the acidic water starts to eat away at the edge of the pool and can turn it into mud. Now, in the spring these things a pretty wet and bubbly. They change throughout the year as the water table drops. This is a picture of just a couple of little bubbles and they’ll throw mud; they can throw mud pretty far really. It’s an incredible thing to see. These things are not necessarily boiling. Up in the Mud Volcano area, some of them have a PH of 1, which is about like battery acid. A lot of them are in the 180 degree range, not necessarily boiling; water boils at 199 at this elevation.
Another type of feature that, at least in the summer you notice a bunch as your looking around the basin, is a fumarole. A fumarole is really just a steam vent. When ever the water is not near the surface and that water is turning to steam by dripping on hot rocks, it just shoots to the surface. So if you are able to watch our webcam in the winter, the spring or the fall, you’ll notice that there are a lot more little steam pockets coming up around the Upper Geyser Basin here than you would find today, when it’s a hot warm day; we just don’t see the steam coming out of the smaller features. Mudpots can also be formed by fumaroles and this is a fumarole that is just under high pressure, just to give you an idea what some of them look like. On the west side of the park, we have a feature called Roaring Mountain. Stagecoach passengers used to say you could hear Roaring Mountain roar from over a mile away. So, acidic fumaroles can also cause mudpots. It’s just a phase, one of the 4 phases of our hot springs.
Let me get rid of this guy here. We’ve talked about mudpots and we’ve talked about fumaroles. Right here next to me is one of the prettier hot springs in the park. This is the most abundant feature we have you can find them all over. They are just beautiful pools where the water is pretty much able to cycle and come to the surface at will.
We get a lot of questions about these hot springs and a lot of those have to do with colors. So, people ask us, “Why does that hot spring look blue?
The blue is just really a trick to our eyes. The sun sends the Earth shortwave radiation and when that shortwave radiation hits our atmosphere, blue light is at one end of the visible spectrum, red lights at the other; blue light scatters more easily than the other types of light. That’s the reason the sky looks blue, it’s the reason the ocean looks blue and it’s the reason a hot spring looks blue. It’s just the blue light is scattering; all the other shades of light are being absorbed down into that pool.
We get questions about the oranges and the browns you see around the hot springs. This stuff is alive. Right here in the Upper Geyser Basin, most of this stuff is considered cyanobacteria. It’s a heat loving microorganism or communities of microorganisms that live at different temperature ranges. The lighter the color of the bacteria, the closer to 167 degrees F; it can give you a way of judging how hot these pools are. We can look at that runoff channel right there and we can see that there is no color in the center of the runoff channel. Then as you move away from the heat source, the bacteria starts. So we can come up with an educated guess that this pool, because it has no bacteria in it, is hotter than 167. That little pool there has bacteria all the way in it; it’s cooler than 167. These bacteria communities can give you an idea, or at least help you come up with an idea, on how hot some of this water is.
We started protecting Yellowstone on March 1st, 1872 and Yellowstone has started to pay us back a little. Back in 1966, there was a professor from the University of Wisconsin- Madison that was out here. His name was Dr. Thomas Brock. Dr Brock identified a thermophile, a little heat loving microorganism that became known as thermus aquaticus or TAQ. TAQ led to the polymerase chain reaction or PCR is what a scientist would say. PCR is what led to DNA finger printing. We knew about DNA, but the process of duplicating a persons DNA is a heat process. Until these heat loving microorganisms where identified it was hard to duplicate DNA on a big enough scale so a scientist or a doctor could read it. So really, DNA finger printing was made possible because we’ve protected Yellowstone since 1872. It’s a pretty cool deal; we believe we’ve only identified about 1% of the microorganisms that live in the thermal areas here in Yellowstone.
We’ve gone through the first 3 types, so lets talk a little about geysers. I’m going to pull this diagram up of the inside of Old Faithful Geyser to start with. This is the surface right here, and this is going to be pretty cool, because we are going to get an eruption of Beehive about half way through this. What happens is, over the year’s rain and snow percolates down through cracks and fissures in the earth and anywhere from 2 to 8 miles below us, there’s liquid rock. This water gets heated and we know that heat wants to rise, so convection currents start.
We’ve got Old Faithful preplaying over there as well, so we might even get a dually coming up, 2 big geysers at once. It’s pretty cool. So this water gets heated and it starts to come back toward the surface. As it comes toward the surface, it’s moving away from the heat source and it’s traveling through rhyolite rock. Rhyolite is rich in silica and so this silica rich solution is moving toward the surface, it’s getting farther from the heat source and that mineral starts to precipitate out of the solution and it coats the inside of the plumbing system. Overtime, a constriction can form. We know that in Old Faithful, 22 feet down, there is a tight spot and it’s just a little over 4 inches wide. We stuck a little camera 50 feet down Old Faithful’s cone some years back. We know that that is where the constriction is in Old Faithful. All geysers have to have a constriction; they have to be boiling at the surface, so it’s a pretty cool thing.
We will show you what this rock is; hold on I’m going to grab my rock. This is geyserite or siliceous sinter. It’s just a silica deposit. As the thermal water evaporates or runs off, this mineral precipitates back out of solution. You call tell that this rock, since it has little beads like that, this rock was formed around a geyser. As the geyser erupted, the water laded on the ground, as the water runs off, that mineral precipitates back out. This stuff grows real slowly, at millimeters a year; this might have taken hundreds of years to build a rock this thick. This rock belongs to the Old Faithful Visitor Center, I borrowed it and I will put it back in a box there. It’s very important that when you visit Yellowstone, we are protecting this place for future generations, you don’t take the rocks, and you don’t pick the flowers; you leave everything you find here for the next visitor. That’s pretty important. We you visit, you can check out the rocks, but don’t pick them up and don’t take them with you.
If we get back to our cross-section, we are still getting close; this is going to be neat.
So, here we go, let’s turn around. Beehive is about to start. I’ll just continue to talk here a little, we’ll tell you about Beehive. The highest recorded eruption of Beehive is about 218 feet. The highest recorded of Old Faithful is 184. You can see Old Faithful steaming, just past Beehive and it’s actually across the river. We are going to see 2 big geysers here in just a couple of minutes from Geyser Hill here. This is pretty cool. Beehive is on about a 14 to 30 hour interval. Here lately it has been going about twice a day. We usually see it once during daylight hours and then it goes once during the middle of the night. Sometimes there are some GOSA people, Geyser Observation and Study Association, they will be out here watching it, so we actually get pretty good times on Beehive even if it erupts in the middle of the night. These people come here on their vacations and a lot of time, they know more about the individual features than us rangers know.
So, you’ve got Beehive Geyser started right at 2:15. This is a pretty cool geyser, it’s a little windy, but it can have burst over 200 feet and it’s under extreme high pressure. One cool thing about Beehive is, you get to stand really, really close. You are almost a football field away from Old Faithful and if you look through the steam, you can see Old Faithful’s doing a little preplaying, which is actually what is going to cause it to erupt. If you can look through that steam spray, you can see Old Faithful spitting, that’s what makes it erupt. Every time it throws a little water out before an eruption, it drops the pressure. It throws a little more out, it drops the pressure. When you start dropping the pressure, you are dropping the boiling point and eventually these super heated pockets of water, that are down below Yellowstone, I mean Old Faithful’s constriction, are able to boil. When water starts to boil and turn into steam, it expands about 1500 times. That steam pocket rushes to the surface. It’s the only way it has to go, straight-up; it’s a steam pocket trying to get out of the ground and it throws all the water above it out of its way. That’s a pretty cool geyser you are seeing right there. A lot of people don’t get to see that; again it only goes about 2 once or twice a day. Some years, I remember 20 years ago or so, there were some summers when they were actually predicting Beehive. It was getting so regular that they would actually predict it at a plus or minus a 2 or 3 hour interval. So, they would give you a 6 hour window. It has been predictable at times. It’s pretty neat; we are hoping that Old Faithful goes while this thing is still going; we’d call that a dually if does. It’s just a pretty neat thing to see. This thing is going under extreme high pressure; you can already see it’s getting shorter; the tallest part of the eruption is probably over.
All the people are sitting there waiting for Old Faithful to go off and there wondering why aren’t we over there watching Beehive. If Beehive went 15 to 20 times a day, like Old Faithful, it might be the most famous geyser in the world, instead of Old Faithful.
Old Faithful sits across the river, by itself. It’s on that big mound; we don’t believe any other geysers have the ability to steal Old Faithful’s juice. Just by watching the statistics over the years, we’ve figured out we can predict some of these geysers. It’s really just an average that we give you. We say, “Over the last 70 years, it’s average this.” For Old Faithful, it’s about every 90 minutes. For Beehive, it’s about every 14 hours. I don’t know if you can hear that through my microphone, but that thing is under real high pressure.
So, if you have any doubts about visiting Yellowstone, these geysers should be giving you some sort of idea. This is a really, really, really special place. All together we have about 400 units in our National Park System and they are all special for different reasons. Some are special for their history, some of them for their culture, some of them for their fantastic seashores and their fantastic cave systems. Yellowstone is fantastic on a large scale for a bunch of different reasons; the geology, the cultural history, the rivers and the lakes; this is an amazing place.
I’m just going to finish up. We went through how these things work. It’s basically just a giant steam pocket coming to the surface. Here in the Upper Geyser Basin, we have about 150 geysers. That’s about 1/4th of all the geysers in the world. So, I’m going to say good-bye to everybody. I hope my mom and dad got to watch; I love you all in Louisville, Kentucky. Thanks for watching, we’ll see you again next summer. We’ll just leave this camera on these geysers and let you watch what happens.
