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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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