top of page

Plate Tectonics: Yellowstone National Park 

 

 
 
April 17, 2016
Dr. James Aber 
Emporia State University
 
Sophia A. Mingoia 

Geologic History of Yellowstone

At the center of Yellowstone’s geological past, present and future lies volcanism. There have been catastrophic volcanic eruptions at Yellowstone circa 2 million years ago, then again 1.2 million years ago and yet again 600,000 years ago ("Volcano"). The most current eruption spewed out nearly 1000 km^3 of debris. What is now the park’s central portion collapsed forming a caldera 45 by 75 km wide. The magmatic heat that was the engine to the aforementioned eruptions still power the geysers, fumaroles, mud pots, and hot springs of today.  The incredible Grand Canyon of the Yellowstone River provides a glimpse of Earth’s interior: rugged mountains flank the park’s volcanic plateau and its waterfalls highlight the boundaries of lava flows and thermal areas ("Geology"). 

Aerial View from Google Earth. Grand Canyon of Yellow Stone. 

 

Topographic Map courtesy of Americansouthwest.net obtained with permission from the creator. 

 

Rocks from the Precambrian are found in northern Yellowstone and in Beartooth, Wind River, Gros Ventre and Teton ranges (Smith and Siegel). During the Precambrian and the subsequent Paleozoic and Mesozoic eras the western part of the country was covered at times by sand dunes, tidal flats, oceans and expansive plains. From the end of the Mesozoic through the early Cenozoic the Rocky Mountains were formed ("Geology").

 

During the Cenozoic era orogenic processes, faulting, volcanism, and glaciation created the Yellowstone area (Smith and Siegel). The Absaroka Range along with the park’s north and east sides were formed by various numbers of volcanic eruptions circa 50 million years ago. This period of volcanism however, is not related to the present Yellowstone volcano. Approximately 30 million years ago enormous expanses of today’s West began to diverge along the east-west axis. These divergent boundaries increased in activity approximately 17 million years ago and continues today forming the modern topography ("Volcano"). 

 

A period of volcanism appeared near the present day intersection of Nevada, Idaho and Oregon approximately 16.5 million years ago (Smith and Siegel). Commonly occurring volcanic eruptions can be tracked across southern Idaho towards Yellowstone. This is composed of a 804 km trail of over 100 calderas that was created as the North American plate moved in a southwestern direction over a shallow pool of magma.  The youngest caldera is in Yellowstone and is approximately 600,000 years old. This means that for the last 16 million years the hotspot has been staying in the same place and the North American plate has moved southwest over the top of it.  This volcanism remains the driving mechanism in Yellowstone today ("Volcano"). 

Geomorphology and the paleoenvironment of Yellowstone National Park​

Courtsey of www.cotf.edu used with permission from the site administrators. 

Map provided by the USGS. 

A cataclysmic eruption of the Yellowstone volcano is not likely in the foreseeable future however monitoring of ground deformation and seismic activity by the Yellowstone Volcano Observatory helps to provide important information and safety to the general public. In 2010, the University of Utah’s seismograph stations had detected over 3,200 earthquakes—which is the largest count since 1985 ("Earthquakes"). This may not mean that the activity of Yellowstone is changing however, new technology has allowed for extensive scientific analysis of smaller earthquakes. Meaning, the earthquakes likely have been happening at this capacity all along, it just was not until late that the earthquakes could be recognized and analyzed.

 

In 2004 lnSAR and GPS measurements indicated that parts of Yellowstone caldera were rising up to 7 cm annually, while the northern caldera boundary started to recede. The largest vertical movement was captured at the White Lake GPS station recorded within the eastern rim where the total uplift from 2004 to 2010 was 27 cm. In the first half of 2010 the caldera began to subside about 5 cm at White Lake. Episodes of subsidence and uplift have been correlated with the occurrence of earthquakes in the park ("Earthquakes").

 

In late March of 2014 a 4.8 magnitude earthquake occurred 6,437 meters north-northeast of Norris Geyser Basin. The 4.8 earthquake was felt in the towns of Gardiner and West Yellowstone, Montana and in Yellowstone National Park. Since, the early 1980s this is the largest earthquake in Yellowstone recorded. Analysis of the 4.8 earthquake indicate a tectonic origin, most likely a strike-slip motion ("Earthquakes"). 

Present Date Volcanic Activity 

and Monitoring 

Introduction to Yellowstone National Park

Yellowstone National Park  was the world's first national park dedicated in 1872 by Ulysses S. Grant. It is designated as a World Heritage Site and Biosphere Reserve. Yellowstone covers approximately 2,221,766 acres or 8,992 km² spanning across three states with 96 percent of the park in Wyoming, 3 percent of the park in Montana and 1 percent in Idaho. It is located on the continental divide within the Middle Rocky Mountains; Yellowstone is on a high plateau averaging 2,438 meters in elevation. The highest point in the park is at Eagle Peak at 3,461 meters and the lowest point is at Reese Creek at 1,609 meters.  About 5 percent of the park is covered by water, 15 percent is covered by grassland and 80 percent is forested (Sanders). 

Yellowstone National Park​ ecology and biodiversity 

Yellowstone forms the center of the Greater Yellowstone Ecosystem (GYE), which is comprised of approximately 18 million acres of land. The GYE has five native forests, two national parks and three national wildlife refuges. This area is the last intact contiguous temperate ecosystem in the world. The GYE still contains almost all of the living organisms found in pre-Columbian times—however not in the same numbers. The biodiversity at Yellowstone ranges from microbe to moose and has been formed and shaped by the Parks underlying geology. Processes of physical weathering, mountain lifting, and glaciation have all shaped the landscape and have played large roles in both the forest and mountain geography. In recent geological time extreme volcanic activity has shaped Yellowstone’s modern day topography (Chan & Duffy). 

Map obtained through Wikimedia Commons (Public Domain).

 

Map was obtained Wikimedia Commons (Public Domain). 

Geothermal activity in Yellowstone National Park

Yellowstone’s hydrothermal system is the visible expression of the vast Yellowstone volcano, they would not be in existence if it were not for the underlying partially molten magma body that releases an enormous amount of heat. They also depend on sources of water, snow and rain slowly percolate downward through the layers of permeable rock-some of the cold water meets the hot brine directly heated by the shallow lying magma body. The water’s temperature in turn rises rapidly above boiling point but the water will remain in a liquid state due to the excessive pressure and weight of the overlying water. The result is water that is heated to greater than 204 degrees Celsius (Hydrothermal Systems").

 

The water is less dense than the cooler, heavier water that sinks around it, creating convection currents that allow for the more buoyant, lighter, superheated water to begin it’s travel back to the surface following the cracks and weak points through rhyolitic lava flows. This path is the natural system of the park’s hydrothermal features. As the hot water travels through the rock it dissolves some silica in the rhyolite. The silica’s dissolution allows for it to precipitate through the cracks and increases the systems ability to withstand the pressure needed to create a geyser (Hermans et al.).

Grand Prismatic Stream is one of more than 10,000 thermal features in Yellowstone. Research on heat-resistant microbes in the park’s thermal areas has led to commercial, forensic and medical uses.

 

Courtesy of : NPS.gov  (Public Domain)

Introduction
Ecology and Biodiversity
Geological History
Hotspots

Summary

The features of Yellowstone National Park are a result of terrific explosive volcanic eruptions and collapse of the ground, uplift and extensive faulting, extremely thick lava flows, and erosion due to ice and flowing water. For over 100 years geologists have analyzed and discovered evidence of the geomorphology of Yellowstone’s landscape. The most directly identified feature with the Yellowstone region is volcanism. Throughout approximately two million years an immense volcanic plateau was built that straddles a high mountain divide. The ecosystem and biodiversity of Yellowstone is immense and is in large supported by the underlying geology. 

References

“Earthquakes.” National Parks Service. Web. 27 Apr. 2016.

 

“Greater Yellowstone ecosystem map.jpg - Wikimedia commons.” Wikimedia Commons. 17 Mar. 2007. Web. 17 Apr. 2016.

 

“Geology.” National Park Service. Web. 17 Apr. 2016.

 

“Grand Prismatic spring - old faithful virtual visitor center.” National Park Service. n.d. Web. 17 Apr. 2016.

 

“Hydrothermal systems.” National Parks Service. Web. 17 Apr. 2016.

 

“Map Yellowstone national park.jpg - Wikimedia commons.” Wikimedia Commons. 26 Aug. 2005. Web. 27 Apr. 2016.

 

“Plate Tectonics.” NASA Classroom of the Future. Web. 17 Apr. 2016.

 

“Volcano.” National Park Service. Web. 17 Apr. 2016.

 

Chan, Lynn, and Katy Duffy. “Greater Yellowstone Ecosystem.” National Parks Service. 2015. Web. 17 Apr. 2016.

 

Crossley, John. “National parks and national monuments of the American southwest and west.” American Southwest. Web. 17 Apr. 2016.

 

Hermans, Linda, et al. “Yellowstone national park geothermal features.” CoolCosmos. 27 Aug. 2013. Web. 17 Apr. 2016.

 

Nance, R. Damian, Thomas R. Worsley, and Judith B. Moody. “The Supercontinent Cycle.” Scientific American 259.1 (1988): 72–79. Web.

 

Program, Volcano Hazards. “USGS: Volcano hazards program YVO Yellowstone.” United States Geological Survey. Web. 17 Apr. 2016.

 

SANDERS, KEVIN. “Yellowstone park fact sheet.” Bearman’s Yellowstone Outdoor Adventures! Web. 21 Apr. 2016.

 

Smith, Robert Baer B., and Lee J. Siegel. Windows into the Earth: The Geologic Story of Yellowstone and Grand Teton National Parks. United States: Oxford University Press, 2000. Print.

Summary
References

How Hotspots work

According to the theory of plate tectonics, the lithosphere contains plates that move with respect to one another at speeds averaging a few centimeters per year. The plates float on the asthenosphere. Most of the plate movements are driven by sea-floor spreading, where the asthenosphere has molten lava rise up and through the lithosphere at high ridges in the oceans floor. It cools and becomes crust, which creates the seafloor. The newly made crust moves at a steady pace away from the mid-ocean ridges outward toward the continents. In cases were the adjacent continent and the seafloor are on the same lithospheric plate the continent is taken along by way of the ocean crust, like a conveyor belt. Subduction can also occur, where the oceanic crust may sink under the continent to rejoin the mantle (Nance, Worsley & Moody).

 

Mantle plumes or hotspots are plumes or columns of molten and hot rock that begin 2,896 km beneath the Earth’s surface at the intersection of Earth’s core and the lower mantle, then flow slowly upward through the mantle and crust, as in the case of Yellowstone. However, new evidence via seismic tomography has been utilized to look at the geology of the upper mantle and crust beneath Yellowstone National Park and Snake River Plain(Smith & Siegel).

 

The studies suggest that the partially molten plume of the Yellowstone hotspot forms within the upper mantle at approximately 201 km underneath Earth’s surface, and may not extend any deeper. The seismic studies found no evidence of partly molten or molten rock below the Yellowstone hotspot at depths of greater than 201 km (Smith & Siegel).

 

Decompressional melting and radioactive decay are the likely heat sources that melt the rock at the base of the Yellowstone hotspot. Uranium and other radioactive elements concentrations in Earth’s mantle generate large amounts of heat through radioactive decay, melting the iron-rich basalt rock, which then rises within the mantle. The other less dense rock is left where it is at and the pressure on the rock is reduced because the basalt is traveling upward. This reduces the melting point of the less dense rock allowing it to melt as well ("Geology").

 

Since molten rock is less dense than the cooler surrounding rock it rises. Beneath the sea the iron-rich basalt regularly erupts from mid-ocean ridges, which pushes the oceanic plates away from the ridges in either direction. The plates are carried along like a conveyor belt by horizontal movement of the underlying mantle, producing the new seafloor. North America drifts southwest over the Yellowstone hotspot because the whole continent is traveling away from the mid-Atlantic ridge, which is located some 8,042 km east of Yellowstone (Smith & Siegel). 

Images in slide show are all courtsey of Mr. Dave Heimann used with permission. 

bottom of page