This National Parks Service, U.S. Department of the

This Term Paper is based on the following sources: “Geology.” ZionNationalPark.com,
2018, www.zionnationalpark.com/explore/guidebook/geology/; Mitchell, Brooks. “Geology of
Zion National Park.” ThoughtCo, 17 Mar. 2017, www.thoughtco.com/geology-of-zion-national-
park-3990193; “Rivers and Streams.” National Parks Service, U.S. Department of the Interior,
www.nps.gov/zion/learn/nature/rivers.htm.; “Weathering/Erosion.” Zion National Park,
http://zion-gardner-bosch.weebly.com/weatheringerosion.html; Wier, S.K. The Geology of Zion
National Park. 2011, www.westernexplorers.us/Geology_of_Zion_NP.pdf.

Zion National Park was formed over 250 million years ago. At first, the region was
covered by low masses of water, only to eventually have large rivers form their way throughout
the area. In time, the region became “one of the largest deserts on the earth.” (“Geology”). The
sand dunes formed in the desert create the cliffs that Zion National Park is most known for.
Within the 229 square mile radius of Zion National Park, there are “enormous pine and juniper
covered plateaus, narrow sandstone canyons, the windy Virgin River, and many seeps, springs,
and waterfalls.” (“Geology”). The formation of Zion National Park is simplified into processes of
sedimentation, lithification, uplift, and erosion that, together, all helped form Zion National Park
into what it is today. The rocks formed at Zion National Park are mostly flat, horizontal layers of
sedimentary rock and the cliffs are comprised of sandstone that were transformed from the
previous sand dunes. After the deposit of these sediments, “the rock layers were uplifted some
two and a half miles (3.8 km), and then incised by erosion of rivers and streams which cut deep
canyons and left behind high cliffs.” (Weir, “The Geology of Zion National Park”).

Zion National Park is a host to many well-known geologic pieces, like the Grand

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Staircase, Navajo Sandstone, Virgin River, and also neighbors the Bryce Canyon and the Grand

Canyon. The time period that the Zion region took place started from the Cretaceous Period,
which formed the Dakota sandstone sediment layer, the youngest layer, and goes all the way
back to the Permian Period, which the Kaibab sediment layer was formed. In between these time
periods, the Jurassic Period had lots of geologic developments that contributed to the formation
of what is now Zion National Park. (Mitchell, Brooks “Geology of Zion National Park”). “The
geologic history of the formation and development of Zion National Park is illustrated below.

The Colorado Plateau and the Grand Staircase

Zion National Park is part of the Colorado Plateau, along with Bryce Canyon and Grand
Canyon. The Colorado Plateau region is “a large, elevated ‘layered cake’ of sedimentary deposits
encompassing much of Utah, Colorado, New Mexico, and Arizona.” (Mitchell, Brooks “Geology
of Zion National Park”). The Colorado Plateau is a host to dry, waterless air and depleted
vegetation, which results in exposed bedrock that has formed in the area.

Over a long period of time, the rock layers that formed in this area were “uplifted, tilted,
and eroded, exposing a series of colorful cliffs” which were named the Grand Staircase.
(“Geology”). The Grand Staircase formed on the southwestern border of the Colorado Plateau. It
is a “geologic sequence of steep cliffs and descending plateaus” that expand from the south,
Bryce Canyon, to the north, Grand Canyon. Zion National Park makes up the middle “step” of
the Grand Staircase. (Mitchell, Brooks “Geology of Zion National Park”). The layers of the
Grand Staircase’s sedimentary rock are grouped by the newer layers, which are the layers that are
formed later and are higher up, and the older layers, which are the layers that have been formed
longer and are lower The lowermost and oldest. The sedimentary rock that is surfaced at Bryce

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Canyon, the lowermost and oldest layers. While the sedimentary rock that is surfaced at higher

layers, the youngest layers, is called the Dakota Sandstone.

Sedimentation

Sedimentation is a process where “gravel, mud and sand eroded down from nearby
mountains and hills and was deposited by streams into this flat basin.” (Mitchell, Brooks
“Geology of Zion National Park”). The Zion National Park consists mostly of flat sedimentary
layers. (Weir, “The Geology of Zion National Park”). This sedimentation process occurred
during the time where Zion was flat and near approximate sea level and continued until there was
a collection of 10,000 feet of material sedimented into layers upon the deposit into the basin.
During this process, the deposits vast weight resulted in the drop-off in elevation. This drop
caused the top surface to reach approximate sea level due to the force of the weight. This rise and
fall of the lands surface elevation due to the change in climate caused “the environment to
fluctuate from coastal plan shallow seas to a desert of windblown sand.” (“Geology”). The
course of the build-up of material took about 10 to 20 million years.Eventually the region was
flooded causing “carbonate deposits and evaporites” to be left behind. (Mitchell, Brooks
“Geology of Zion National Park”).

A process called “crossbedding” created “inclined layers” which were a result of “sand
dunes that appeared during the Jurassic period and formed on top of each other” exemplified
by the Checkerboard Mesa (Mitchell, Brooks “Geology of Zion National Park”). The process had
“enormous sand dunes with sloping faces were gradually buried by more dunes and, in time,
converted into a thick uniform sandstone unit, called the Navajo sandstone, which preserves the
sloping dune faces as sloping lines crossing cliffs and rock exposures.” (Weir, “The Geology of

Zion National Park”).

Lithification

The layers of deposits that were formed from sedimentation are then “lithified into rock
as mineral-laden water slowly made its way through it and cemented the sediment grains
together.” (Mitchell, Brooks “Geology of Zion National Park”). The water mimics the actions of
adhesive agents that cemented the layers of compact sediments. Over prolonged time periods,
“iron oxide, calcium carbonate, and silica transformed layers into stone.” (“Geology”). The
transformation of “ancient seabeds turned to limestone, mud and clay became mudstones and
shale, and desert sand transformed into sandstone” (“Geology”). Due to the distinction in sources
of sediments that form during the course of lithification, the sediment layers are now “different
in thickness, color, mineral content, and overall appearance” which creates the variation in colors
and thickness of layers formed, which occurred as each layer of sediment rock transformed.
(“Geology”).

Uplift

Uplift is a process where “forces deep within the earth pushed the surface up.”
(“Geology”). This resulted in Zion and the Colorado Plateau’s slowly increased elevation to rise
from approximate sea level to nearly 10,000 feet elevation above sea level caused by the vertical
push of the earth’s crust from the inside of the earth. For about 430 million years during its
geologic formation, Zion was near sea level, yet since then the process of uplift has taken place.
This process produced “runoff streams with more speed thus allowing them to carry more
sediment and eroding more rock” eventually forming the narrow canyons that are a presently a
major landmark in Zion National Park. (“Weathering/Erosion”). This is a process that is still

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ongoing and continues to produce major landmarks in Zion National Park. Zion National Park

and the Colorado Plateau have become known for the flat sedimentary rock that are placed at
high elevation since uplift have taken place.

The continuous uplift that is still occurring today increases Zion National Park’s
susceptibility to earthquakes. Although most earthquakes that occur in the area are minor, a
recent earthquake in 1992 with a magnitude of 5.8 “caused landslides and other damage.”
(“Mitchell, Brooks “Geology of Zion National Park)”.

Zion National Park and the other canyons that form the Colorado Plateau sits at a range of
up to 10,000 feet above sea level.

Erosion

When the region that is now called Zion National Park first came about approximately
250 million years ago, it was a flat basin, near sea level. During that time since then, “debris
from the surrounding mountains accumulated it formed a pattern of deserts and shallow inland
seas building up sediment … eventually accumulating 10,000 feet of sediment over the years.”
(“Weathering/Erosion”). This process is still ongoing and it continues to make deeper canyons.

Following the process of uplift and its contribution to erosion, there was now streams that
made a path to the sea. The streams “tumbled rapidly off of the plateau … cut into the rock
layers, carrying sediment and large boulders with them, as a result forming deep and narrow
canyons.” (“Geology”).

A lake came about when the Virgin River was dammed by a landslide. (“Geology”). “As
sediment settled to the bottom of the still waters, the river breached and the lake drained, and as
a result, what was left was a flat-bottomed valley.” (“Geology”). The flash floods that often

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come through the region of Zion also helped form what is there today. The floods aid in the

improved increase of water that flows through the region but also causes damage to the path that
goes through the area. (“Geology”).

The Virgin River, presently, is the main tributary that flows through Zion National Park.
Because of this body of water, erosion continues to process through Zion. The massively steep
Virgin River starts at 9,000 feet above sea level and drops to 1,000 feet above sea level over the
course of 160 miles. (“Rivers and Streams”). This steepness, in turn, is a result of the uplift that
took place of the Colorado Plateau. (“Rivers and Streams”). The importance of the Virgin River
is that it “transports one million tons of sediment every year.” (“Rivers and Streams”). The power
of force that comes with the strength of the Virgin River joins forces with floods that “carry large
boulders and rip cottonwood trees out of the ground.” (“Rivers and Streams”).

Conclusion

The Zion National Park is a remarkable formation that has so much history. Over a period
of approximately 250 million years, and counting, the processes of sedimentation, lithification,
uplift, and erosion created Zion National Park and the rest of the Colorado Plateau, as well as,
the Grand Staircase, which is a marvel, in and of itself that is apart of Zion National Park. Many
of these processes are still occurring till this day, like uplift. Zion National Park went from once
being covered in “ancient sand dunes, shallow ocean bottoms, and swamp lands” to fascinating
cliffs, mountains, and narrow canyons that have formed in its place. (“Geology”). In addition, the
interesting part is the transition from bodies of water covering such large areas to the drastic
transformation to what was considered to be one of the largest deserts on the earth. The desert
area is what came to be known as Zion National Park, that is host to the scenic views, cliffs,

rivers, waterfalls, and mountains. (“Geology”).

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References
“Geology.” ZionNationalPark.com, 2018,

www.zionnationalpark.com/explore/guidebook/geology/.
Mitchell, Brooks. “Geology of Zion National Park.” ThoughtCo, 17 Mar. 2017,

www.thoughtco.com/geology-of-zion-national-park-3990193.
“Rivers and Streams.” National Parks Service, U.S. Department of the Interior,

www.nps.gov/zion/learn/nature/rivers.htm.
“Weathering/Erosion.” Zion National Park, http://zion-gardner-

bosch.weebly.com/weatheringerosion.html
Wier, S.K. The Geology of Zion National Park. 2011,

www.westernexplorers.us/Geology_of_Zion_NP.pdf.