Yellowstone National Park, WY

Updated: Apr 20

Yellowstone, America's first national park, was established in 1872 by President Ulysses Grant. Yellowstone is also a designated World Heritage Site and a designated Biosphere Reserve. The park is primarily located in Wyoming with smaller sections in Montana and Idaho. This is not a region normally associated with volcanoes, but it's the volcanic environment surrounding Yellowstone that creates the unique beauty of the park.


A large portion of the national park sits atop the Yellowstone Volcano, one of the world’s largest active volcanoes. The first major eruption of this volcano occurred 2.1 million years ago and covered more than 5,790 square miles with ash. That's among the largest volcanic eruptions known, and marks Yellowstone as a supervolcano.


The last time the Yellowstone Supervolcano erupted was 640,000+ years ago. Following this eruption, the area collapsed upon itself, creating a sunken giant crater or caldera measuring about 34 miles by 45 miles. The magmatic heat powering that eruption and two others major events still powers the park’s famous geysers, hot springs, fumaroles, and mud pots.

Numerous rivers run through Yellowstone - meandering and tranquil environments that don't hint at the bubbling cauldron that exists beneath the surface of this incredible National Park. In fact, half of the world's geysers and hydrothermal features are in Yellowstone, all fueled by this ongoing volcanism.

Firehole Falls is an 80-foot waterfall off the side of the road


Hydrothermal Features in Yellowstone

More than 10,000 hydrothermal features, an extraordinary collection of hot springs, mudpots, fumaroles, travertine terraces and geysers, can be found in Yellowstone National Park.

The vivid colors in the hot springs are the result of microorganisms called thermophiles -- meaning “heat loving” -- that live in these features and give the park its brilliant colors. The amount of color in the microbial mats depends on the temperature and pH of the water and the microbes present. The center of the spring is just above its underground water source, and it's where temperatures are the highest — up to 189°F. The water is too hot for most microbial growth and therefore is mostly clear. The center of the spring is blue as a result of the scattering of light by the water's surface. Moving further from the center, the water temperature drops and the diversity of microbes increases and the pigments they produce change. Typical color transition zones are: blue-green-yellow-orange-brown.

Fountain Paint Pot

The Fountain Paint Pot is named for the reds, yellows and browns of the mud in this area. As with all hot springs, the heat in the caldera forces pressurized water up through the ground, which is expelled here. Also, rising gasses cause the bubbling action. The bubble action in the mud varies with the seasons. In the early summer, the mud is watery from the high water table due to rain and snow melt. By the end of summer, the mud is much thicker as the water table drops.


These dead lodgepole pine trees are pioneers that did not survive. These trees drowned in superheated water when nearby hot springs shifted. Silica from the hot springs penetrated the trees and hardened their bases - so even in death they continue standing.

A raised boardwalk provides access to many of the hydrothermal features in Fountain Paint Pot. Despite warnings posted everywhere in Yellowstone, every year people wonder off the boardwalk and suffer extreme burns or excruciating death.

Celestine Spring is one of the most beautiful hot springs on this trail. No documentation exists of how this spring was named, but its blue color does seem to match the deep blue of the sky. As in many of the pools around Yellowstone, the water in this pool is usually within a few degrees of boiling. There is little hope of surviving a fall into such a pool.

After the Hebgen Lake earthquake in 1959 (magnitude 7.2), several new geothermal areas developed including Red Spouter. Red Spouter may sometimes look like a small geyser but it is actually a fumarole that sometimes gets drowned by a puddle of water that forms near its vent and resembles a mudpot.


In simplest terms, a fumarole is a vent in the Earth's crust. The supply of water around fumaroles is not as plentiful as in hot springs and geysers. Modest amounts of groundwater come into contact with hot rocks underground and are turned to steam. This steam rushes up through a series of cracks and fissures and out the vent, sometimes with enough force to create a loud hiss or roar.

Mud pots are formed where steam and acidic fluids with limited water eat away at surrounding rocks. It usually takes the form of a turbulent pool of hot bubbling mud and typically smells like rotten eggs because it contains sulfuric acid. They aren't as picturesque as hot springs but that are another unique feature of Yellowstone.

Here are a few other interesting photos from this area.


Grand Prismatic Springs at Midway Geyser Basin

Rudyard Kipling, who visited Yellowstone in 1889, immortalized this basin by referring to it as "Hell's Half Acre". Despite its small size, Midway possesses Grand Prismatic Spring, the largest hot spring in Yellowstone nearly 370 feet in diameter. It is considered to be the third largest in the world; New Zealand has the two largest springs.


This hot spring forms when heated water emerges through cracks at temperatures ranging from 147-188 °F. Unlike geysers, which have obstructions near the surface, water from hot springs flows unobstructed, creating a nonstop cycle of hot water rising, cooling and falling. In the Grand Prismatic Spring, this constant cycle creates rings of distinct temperatures around the center: very, very hot water bubbles up from the middle and gradually cools as it spreads out across the spring's massive surface. The dazzling colors are attributed to the various species of thermophilic bacteria living in the spring.


The colors begin with a deep blue center surrounded by rings of color ranging from red to green. The otherworldly effect is caused by varieties of pigmented bacteria and microbes that thrive in the warm, mineral, and abundant waters surrounding the hot spring. Green algae forms beyond the shallow edge. Outside the scalloped rim a band of yellow fades into orange.

Grand Prismatic Spring is extremely deep, with water traveling over 120 feet from a crack in the Earth to reach the surface.

In the center of the pool the water that boils up from underground is so hot that it's actually sterile. This produces a shockingly clear and bold blue color that the spring maintains year-round.

As you move farther from the heat source of the spring, life begins to flourish. The cyanobacteria – aquatic photosynthesizing bacteria -- that live at the edges of Grand Prismatic Spring cover the color spectrum including yellow, green, orange, red, and brown.

Another major feature at Midway is Excelsior Geyser. Excelsior was once the largest geyser in the world. However, the last known major eruptions occurred during the 1880s, when water was propelled over 300 feet high. It is believed these powerful eruptions damaged the geyser's internal plumbing system allowing gas leakage and the loss of thermal energy.

Excelsior is now a productive hot spring with temperatures exceeding 199 °F. Numerous vents boil and churn the water within the crater, covering it in a dense layer of steam.

The hot spring discharges over 4,000 gallons/minute, which cascades over the hills and mounds into the adequately named Firehole River.

There are more than 15 miles of boardwalk in the park which provides visitors to experience these natural wonders up close.


Beryl Spring

Beryl Spring is one of the hottest springs in Yellowstone, averaging 196 °F. It's a large super heated pool, and boils up to a height of 4 feet. On a cold fall morning, the steam around Beryl creates a winter-like appearance.

In the fall and winter, steam from Beryl freezes on the tree branches surrounding the hot spring and creates a winter wonderland-like environment.


Old Faithful Geyser and Geyser Hill Loop

Yellowstone is one of the few places in the world where geysers occur. The essentials for geysers and hot springs exist here. Snow and rain provide water, heat from deep in the earth warms the rock and water above it, and fractures in the rock provide the "plumbing" through which the water circulates. A geyser's channels have constrictions that prevent the water from circulating freely to the surface where the heat would escape. Pressure builds. Steam rises and is trapped by the constrictions and overlying cooler water. At a critical point the confined steam actually lifts the cooler water and causes the geyser to overflow or splash. Pressure release continues, more steam rises and forces water out of the vent. The eruption begins.


Old Faithful is not the tallest or largest geyser in the park; those titles belong to the less predictable Steamboat Geyser. The reliability of Old Faithful can be attributed to the fact that it is not connected to any other thermal features of the Upper Geyser Basin. Eruptions can shoot 3,700 to 8,400 gallons of boiling water (average temperature 204° F) to a height of 106 to 185 feet lasting from ​1 1⁄2 to 5 minutes.

Intervals between eruptions can range from 60 to 110 minutes. During the last few decades, the average interval between eruptions has lengthened, causing some to question its faithfulness.

The mile long Geyser Loop Trail provides visitors a good chance of seeing a variety of geysers.

While on Geyser Hill Loop, we had a chance to see a good number of bison. We were cautious and gave them plenty of space. Yellowstone has the largest, free-roaming herd of bison in the world.

Taken from a safe distance using a zoom lens.

The boardwalk passed by numerous colorful hydrothermal pools and springs bubbling to the surface.

Doublet Pool is 8 feet deep and its temperature is approximately 194.4° F . Its scalloped edge is made of geyserite a form of opaline silica that is often found around hot springs and geysers.

Lion Geyser is a cone-type geyser named for the roaring sound of steam releasing during an eruption. Eruptions can reach 90 feet and last from 1 to 7 minutes.

Lion is the largest of the Lion Group which includes Little Cub Geyser and the currently inactive Big Cub and Lioness geysers

An eruption at Beehive Geyser caught us by surprise. Eruptions of Beehive last about 5 minutes with water rising upwards of 200 feet.

A short video of one of the bubbling hot springs in the Geyser Loop trail.

After walking around the Geyser Hill Loop we took a short side trail that led to Mystic Falls.

The trail followed the Little Foxhole River.

After a few minutes it began to rain but that quickly turned to hail. Since it was a short hike we chose to ignore the weather

It wasn't long before the falls came into view.

Mystic Falls itself is a spectacular waterfall which cascades about 70 feet down off the Madison Plateau.

It is unique among Yellowstone’s waterfalls in that thermal activity is visible from the bottom all the way to the top of the falls, with clouds of steam rising from seemingly dozens of places at the top, sides and bottom of the waterfall.

On the way back, we came upon a huge elk that was startled and quickly ran into the woods. It sounded more like an elephant than a graceful deer and I'm not sure who was startled more the elk or us.

We had an incredible sunset that evening driving back to the hotel.


Grand Canyon of Yellowstone

The Yellowstone River begins on the slopes of Yount Peak in the Absaroka Range of Wyoming. It then flows through Yellowstone National Park, streaming in and out of Yellowstone Lake.

At the entrance to Yellowstone Canyon, it plummets 422 feet to the canyon floor.

The Grand Canyon of Yellowstone is more than 1,000 feet deep, 1,500-4,000 feet wide and roughly 20 miles long -- it provides endless views. The colors in the canyon are a result of hydrothermal alteration. The rhyolite in the canyon contains a variety of different iron compounds. When the old geyser basin was active, the "cooking" of the rock caused chemical alterations in these iron compounds. Exposure to the elements caused the rocks to change colors. The rocks are, in effect, oxidizing; the canyon is rusting.

According to Ken Pierce, US Geological Survey geologist, at the end of the last glacial period, about 14,000 to 18,000 years ago, ice dams formed at the mouth of Yellowstone Lake. When the ice dams melted, a great volume of water was released downstream causing massive flash floods and immediate and catastrophic erosion of the present-day canyon. These flash floods probably happened more than once. The canyon is a classic V-shaped valley, indicative of river-type erosion rather than glaciation. The canyon is still being eroded by the Yellowstone River.

At 692 miles long, Yellowstone River is the longest undammed river in the continental US. The river runs out of the park in Gardiner, Montana, working its way eastward out of Montana and into North Dakota, where it eventually joins the Missouri River.


Mammoth Hot Springs

On the drive to Mammoth Hot Springs we passed Calcite Springs Overlook at the north end of the Grand Canyon of Yellowstone, where the Yellowstone River leaves the steep canyon walls for rolling prairie grasses.

Chemicals from Calcite Springs’ hot water vents that run along the Yellowstone River banks are slowly turning the cliff to whitish, yellowish pulp.

Another interesting feature runs along the opposite wall of the canyon - a line of uniform volcanic pillars. The basalt columns testify to a more active volcanic period in Yellowstone’s past, when a 25-foot layer of lava flowed across the land. As the lava cooled and contracted about 1.3 million years ago, it formed these columns of basalt. Above and below the basalt lies a loose mix of gravel carried here by glacial meltwater.

Our last major stop in Yellowstone was Mammoth Hot Springs. Mammoth Hot Springs, located inside the north entrance to Yellowstone National Park, consists of nearly 100 hot springs scattered over a score of step-like travertine (limestone) terraces.

Several key ingredients combine to make the Mammoth Hot Springs Terraces: heat, water, limestone, and a rock fracture system through which hot water can reach the earth's surface.

Travertine terraces are formed from limestone. Thermal water rises through the limestone, carrying high amounts of the dissolved limestone (calcium carbonate). At the surface, carbon dioxide is released and calcium carbonate is deposited, forming travertine, the chalky white mineral forming the rock of travertine terraces. The formations resemble a cave turned inside out. Colorful stripes are formed by thermophiles, or heat-loving organisms.

To put the size of these travertine terraces in perspective, I've included this photograph courtesy of the US National Park Service.

Yellowstone is home to incredible number of animals. We were lucky to observe a few close enough to use a zoom lens to capture a good photo.

What an amazing adventure in the grande dame of National Parks - Yellowstone. The first is possibly the best in the US.

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