This Term Paper is based on the following sources: “Geology.” ZionNationalPark.com,2018, www.
zionnationalpark.com/explore/guidebook/geology/; Mitchell, Brooks. “Geology ofZion 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 ZionNational Park. 2011, www.westernexplorers.us/Geology_of_Zion_NP.
pdf. Zion National Park was formed over 250 million years ago. At first, the region wascovered by low masses of water, only to eventually have large rivers form their way throughoutthe area. In time, the region became “one of the largest deserts on the earth.” (“Geology”). Thesand 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 junipercovered 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 ofsedimentation, lithification, uplift, and erosion that, together, all helped form Zion National Parkinto what it is today. The rocks formed at Zion National Park are mostly flat, horizontal layers ofsedimentary rock and the cliffs are comprised of sandstone that were transformed from theprevious sand dunes. After the deposit of these sediments, “the rock layers were uplifted sometwo and a half miles (3.8 km), and then incised by erosion of rivers and streams which cut deepcanyons 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 Bootesaz 2 Bootesaz 3Staircase, 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 wayback to the Permian Period, which the Kaibab sediment layer was formed. In between these timeperiods, the Jurassic Period had lots of geologic developments that contributed to the formationof what is now Zion National Park. (Mitchell, Brooks “Geology of Zion National Park”). “Thegeologic 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 GrandCanyon. The Colorado Plateau region is “a large, elevated ‘layered cake’ of sedimentary depositsencompassing much of Utah, Colorado, New Mexico, and Arizona.” (Mitchell, Brooks “Geologyof Zion National Park”). The Colorado Plateau is a host to dry, waterless air and depletedvegetation, 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.
Itis 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” ofthe Grand Staircase. (Mitchell, Brooks “Geology of Zion National Park”). The layers of theGrand Staircase’s sedimentary rock are grouped by the newer layers, which are the layers that areformed later and are higher up, and the older layers, which are the layers that have been formedlonger and are lower The lowermost and oldest. The sedimentary rock that is surfaced at Bryce Bootesaz 4Canyon, 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 nearbymountains 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 sedimentarylayers. (Weir, “The Geology of Zion National Park”). This sedimentation process occurredduring the time where Zion was flat and near approximate sea level and continued until there wasa 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 dropcaused the top surface to reach approximate sea level due to the force of the weight. This rise andfall of the lands surface elevation due to the change in climate caused “the environment tofluctuate from coastal plan shallow seas to a desert of windblown sand.” (“Geology”). Thecourse of the build-up of material took about 10 to 20 million years.
Eventually the region wasflooded 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 “sanddunes that appeared during the Jurassic period and formed on top of each other” exemplifiedby 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 thesloping 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 rockas mineral-laden water slowly made its way through it and cemented the sediment grainstogether.” (Mitchell, Brooks “Geology of Zion National Park”). The water mimics the actions ofadhesive agents that cemented the layers of compact sediments. Over prolonged time periods,”iron oxide, calcium carbonate, and silica transformed layers into stone.” (“Geology”).
Thetransformation of “ancient seabeds turned to limestone, mud and clay became mudstones andshale, and desert sand transformed into sandstone” (“Geology”). Due to the distinction in sourcesof sediments that form during the course of lithification, the sediment layers are now “differentin thickness, color, mineral content, and overall appearance” which creates the variation in colorsand 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 risefrom approximate sea level to nearly 10,000 feet elevation above sea level caused by the verticalpush of the earth’s crust from the inside of the earth. For about 430 million years during itsgeologic 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 moresediment and eroding more rock” eventually forming the narrow canyons that are a presently amajor landmark in Zion National Park.
(“Weathering/Erosion”). This is a process that is still Bootesaz 5 Bootesaz 6ongoing 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 athigh elevation since uplift have taken place. The continuous uplift that is still occurring today increases Zion National Park’ssusceptibility to earthquakes. Although most earthquakes that occur in the area are minor, arecent 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 ofup to 10,000 feet above sea level. Erosion When the region that is now called Zion National Park first came about approximately250 million years ago, it was a flat basin, near sea level. During that time since then, “debrisfrom the surrounding mountains accumulated it formed a pattern of deserts and shallow inlandseas 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 thatmade a path to the sea. The streams “tumbled rapidly off of the plateau … cut into the rocklayers, carrying sediment and large boulders with them, as a result forming deep and narrowcanyons.” (“Geology”).
A lake came about when the Virgin River was dammed by a landslide. (“Geology”). “Assediment settled to the bottom of the still waters, the river breached and the lake drained, and asa result, what was left was a flat-bottomed valley.” (“Geology”). The flash floods that often Bootesaz 7come 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 thatgoes 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 steepVirgin River starts at 9,000 feet above sea level and drops to 1,000 feet above sea level over thecourse of 160 miles. (“Rivers and Streams”). This steepness, in turn, is a result of the uplift thattook place of the Colorado Plateau.
(“Rivers and Streams”). The importance of the Virgin Riveris that it “transports one million tons of sediment every year.” (“Rivers and Streams”). The powerof force that comes with the strength of the Virgin River joins forces with floods that “carry largeboulders 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 periodof 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. Manyof these processes are still occurring till this day, like uplift. Zion National Park went from oncebeing covered in “ancient sand dunes, shallow ocean bottoms, and swamp lands” to fascinatingcliffs, mountains, and narrow canyons that have formed in its place. (“Geology”). In addition, theinteresting part is the transition from bodies of water covering such large areas to the drastictransformation to what was considered to be one of the largest deserts on the earth. The desertarea is what came to be known as Zion National Park, that is host to the scenic views, cliffs, rivers, waterfalls, and mountains.