Kathryn Erickson

Professor Inkenbrandt

Geology 1010

November 18, 2018

Earth’s Heartbeat

By Kathryn Erickson

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For my Geology field trip, I went to Yellowstone National Park from September 7, 2018

to September 19, 2018. Within this two week period, I got to explore and observe the many

geological features within Yellowstone that make it stand out from the rest of the nearby

landscape, and are what tell the story of its formation. Some of these geological features (among

many others) were the extinct volcano: Mount Washburn, a part of the Yellowstone caldera rim

that could be seen from the road, canyon walls made of Rhyolite in the Firehole Canyon,

columns of Basalt that skirted the Grand Canyon of the Yellowstone, and a rare eruption of the

world’s tallest geyser: Steamboat Geyser. It is features like these that reveal strong evidence of

there being something bigger and very powerful underneath that is their driving force: a Hotspot.

Over a span between 2.1 million years to 640,000 years ago, 3 large calderas formed due

to the occurrence of 3 large eruptions in the upper left corner of Wyoming and are now currently

the foundation of Yellowstone National Park (Breining, 2010). These 3 eruptions were triggered

as the lithosphere from the North American Plate became heated and swelled after moving over a

Hotspot (Breining, 2010). Journalist, Greg

Breining used an analogy in his book, Super

Volcano: The Ticking Time Bomb, when

relating how a Hotspot worked very similar to

us moving our hand over a flame on a candle.

As we move our hand, the flame will never

change its position, but it is the movement of

our hand that will reflect where it intersected the

heat of the flame (Breining, 2010). As these eruptions occurred from the force of heated magma

underneath, one feature that was drastically affected and transformed from the power of the blast

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Mount Washburn, Yellowstone National Park

was Mt. Washburn. Standing at an elevation of 10,223’, Mt. Washburn is one of the tallest peaks

within the Washburn range. Though Mt. Washburn is no longer an active volcano, back at the

time of the eruptions it was very much alive, and was deformed to almost half of its size from the

nuclear like force that was given off from the blasts (Breining, 2010). Mt. Washburn was one of

the geological features that I got to observe on my field

trip, and is where I found and collected many pieces of

Obsidian or volcanic glass that reflected this peak’s

volcanic past. As ash and debris were released into the

air resulting from the large eruptions, it not only affected

the atmosphere for many years in the future, but this

ash and debris has also partially filled the bottoms of

the caldera’s over time, and has made them less identifiable to the eye (Breining, 2010).

However, one feature that has helped to still prove and define the caldera’s presence is part of its

rim near Madison Junction in Yellowstone National Park.

On my trip to Yellowstone, I got to observe a part of its caldera rim near Madison

Junction that was visible from the road. When the

most recent eruption happened 640,000 years ago

pyroclastic flows of ash helped form the

Yellowstone Caldera (Hendrix, 2011). As this ash

landed and became heated from the lava, it then

began to fuse together and turned into welded

tuff, which is what most of the caldera is made of

(Hendrix, 2011). Because tuff is a weaker type of

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Caldera rim, near Madison Junction.Yellowstone National Park

rock due to trapped gases within it, soon after the caldera formed, a part of the caldera edge gave

way to its own weight and landslided below where it originally formed (Hendrix, 2011).

Another geological feature of the park that shows past history

of eruptions and lava flows is the canyon walls made of

rhyolite in Firehole Canyon, which is also near the Madison

Junction. Throughout this course, we have learned much about

rocks, their composition, and how to identify them based on

their physical appearance. Rhyolite was one of the rocks

discussed in chapter 4 of our textbook, and it was this

information that helped me identify this rock that made the

Firehole Canyon walls. The textbook discussed how the

composition of a rock was based on the composition and cooling of the lava, and because

Rhyolite is finer-grained and lighter in color (greyish-tan), this would mean that the magma that

formed it cooled quickly, and was felsic. By knowing this information, as I got out to look closer

at the rock that formed the canyon, I was able to match its greyish color and fine-grain to the

description of Rhyolite given in the textbook (learning that most of Yellowstone was made from

Rhyolite kind of helped too ;). In the book, Roadside Geology of the Yellowstone Country,

Geologist, William Fritz mentioned how when tree cover makes it so difficult to see much of the

geology within Yellowstone, the canyon walls of Rhyolite in Firehole is one of the few places in

the park that shows it well (Fritz, 2011). Another one of these few places in the park that is not

covered with trees and displays Yellowstone’s geology well is the Grand Canyon of the

Yellowstone that can be viewed from the Calcite Springs overlook at Tower Junction.

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Walls of Rhyolite in Firehole CanyonYellowstone National Park

During the middle of my field trip, the Calcite Springs overlook was one stop I took

where I was able to look at the strange columns of rock that skirted all along the top part of the

canyon of the Yellowstone. They were directly across from where I was standing on the other

side of the canyon, and they had a very

unnatural shape to them that is not commonly

found in nature. Back during the second

eruption that was 1.3 million years ago, much

of the lava flows that took place were of low

viscosity because of how close the magma

was to the earth’s surface. This gave the

magma only a short distance to travel (due to the

magma plume underneath) to reach the surface quickly, and is the same kind of lava that forms

the bottoms of our oceans and creates Basalt (Smith, 2000). As this lava started to cool, parts of

it began to crack allowing new lava to squeeze in between them, and this is what created the

vertical columns of Basalt along the canyon wall (Smith, 2000).

Throughout my field trip, I got to see many geological features. But the one that was the

most rare and unique to see was an eruption performed by Steamboat Geyser. The hotspot that is

currently below Yellowstone not only has formed calderas, solidified lava flows etc., but it has

also created half of the world’s geothermal features like hotpots and geysers (Bryan, 2018).

As the magma from the hotspot rises closer towards the earth’s surface, the heat that is

radiated from it warms up both groundwater and bodies of water that lay above it from previous

rainfall and snowmelt (Smith, 2018). As this water heats, bodies of water rise to temperatures as

high as 157 degrees F, and become hotpots like Morning Glory pool located in the upper geyser

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Columns of Basalt near Tower Junction.Yellowstone National Park

basin near Old Faithful (Smith, 2018). As

groundwater heats, it begins to rise and travels

towards the surface through small cracks within

the ground (Smith, 2018). When these cracks

become narrower, pressure builds up, and

eventually is released from under the ground and

creates a geyser (Smith, 2018). Reaching a

height of 250 ft, Steamboat Geyser is the tallest

geyser in the world, and is also located in the hottest geyser basin in the world: Norris Geyser

Basin (Smith, 2018). With its last eruption being back in 2014, Steamboat Geyser randomly

began to once again erupt starting in June of this year (Smith, 2018). Since then, it has had 10

more eruptions (GeyserTimes, 2018). With as many eruptions that Steamboat Geyser has made

this year, it is theorized that shifting in the ground due to earthquakes are what have most likely

caused this to happen (Smith, 2018). Out of the many

eruptions that Steamboat has made this year, while on my

field trip there, I got a once in a lifetime opportunity (along

with many others) to see its 1 hour 15 minute long eruption

that took place on September 17, 2018.

With the many geological wonders that lay within

Yellowstone National Park, I got the chance to explore and

observe just some of them while on my geology field trip.

From getting to hike to the top of a once live volcano, to

observing part of the caldera rim that was formed 640,000 years ago, and getting an up close

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Morning Glory Pool.Yellowstone National Park

September 17, 2018 eruption of Steamboat Geyser,

Yellowstone National Park

look of what used to be a flowing river of lava and is now a solid wall of Rhyolite in the Firehole

Canyon; the powerful forces of a hotspot were revealed to me, and it was made known to where

earth’s heartbeat truly lies.

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September 17, 2018 eruption of Steamboat Geyser,

Yellowstone National Park

Works Cited:

Breining, G. (2010). Super volcano: The ticking time bomb beneath Yellowstone National

Park. St. Paul, MN: Voyageur Press.

Bryan, T. S. (2018). The geysers of Yellowstone (5th ed.). Louisville, CO: University Press of

Colorado.

Fritz, W. J., & Thomas, R. C. (2011). Roadside geology of Yellowstone Country (2nd ed.).

Missoula, MT: Mountain Press Pub.

Hendrix, M. S. (2011). Geology underfoot in Yellowstone country. Missoula, Mont:

Mountain Press Pub.

Johnson, C., Affolter, M., Inkenbrandt, P., & Mosher, C. (2017). An Introduction to

Geology. Retrieved November 20, 2018, from http://opengeology.org/textbook/

Smith, R. B., & Siegel, L. J. (2000). Windows into the earth: The geologic story of

Yellowstone and Grand Teton National Parks (1st ed.). New York City, NY: Oxford

University Press.

Steamboat Geyser. (2018). Retrieved November 20, 2018, from

https://geysertimes.org/geyser.php?id=Steamboat

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Google Earth Map: My travel route through Yellowstone National Park:

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