My next post about the Geology of the National Parks Through Pictures is from our move across the country from Utah to New York. Along the way we visited 13 National Parks as well as some other sites. This was the 2nd National Park along the way.
You can find more Geology of the National Parks Through Pictures as well as my Geological State Symbols Across America series at my website Dinojim.com.
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Obligatory entrance sign.
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This is one of the more "unique" entries in the National Park list, since there is not much to it. They wanted a park to connect Yellowstone NP with Grand Teton NP, so they made this one. There is only one place to stop and that is this "visitor's center". When we came through back in 2010, we stopped here however the mosquitoes were so bad here I literally jumped out of the car, snapped some pictures, went inside the building for 5 second, then left. The park doesn't even have its own webpage, they use part of the Grand Teton NP webpage.
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| Looking north across the park |
The park itself is a changeover from the tectonic expansion seen that formed the Teton Mountains (as we talked about in the Grand Teton National Park post) to the volcanic effects of the Yellowstone hotspot (as we will talk about in the next post). Even though the park is dominated by Yellowstone volcanism some of the very northern extents of the rocks that make up the Teton mountains can be seen within the southern edges of the park, mainly in the form of Jurassic and Cretaceous sandstone and shale. The topography here is also much more smoothed out as compared to the rugged peaks within Grand Teton NP.
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| Yellowstone volcano movement through North America. Image courtesy of NPS.gov. |
Of the two neighboring influences, the Yellowstone volcano has a much larger impact within the park. As will be discussed in post covering Yellowstone National Park, Yellowstone is a hotspot volcano, meaning the volcano essentially stays in one place while the plate moves over the top of it. In this instance, it is the North American plate. This is a similar type of volcano as the Hawaiian hotspot. Over the past several millions of years, the path of the Yellowstone hotspot can be tracked by historical eruptions, and previous volcano calderas. The caldera is the depression on the top of a volcano, from which most eruptions emanate from. Craters of the Moon National Monument and Preserve is also a remnant of past Yellowstone eruptive activity.
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| The most recent Yellowstone calderas, within and surrounding the current boundaries to Yellowstone National Park. Image courtesy of NPS.gov. |
Within, and just outside, the current Yellowstone National Park can be seen the remnants of three calderas, ranging in age from 2.1 million years old to 631 hundred thousand years old. The oldest of these three calderas dates to 2.1 million years old and is known as the Huckleberry Ridge Eruption. The remnants of the Huckleberry Ridge caldera extend down into the John D. Rockefeller Jr. Memorial Parkway in the form of Lewis Canyon Rhyolite (the large pink mass in the geological map below).
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| Geological map of the John D. Rockefeller Jr. Memorial Parkway. Image courtesy of NPS.gov. A map key can also be found below. |
The initial 2.1 million year old eruption produced the Huckleberry Ridge Tuff, which is a rock formed from the consolidation of the erupted ash. Immediately following the deposition of the Huckleberry Ridge Tuff, several bulbous, rhyolitic lava flows were erupted which then formed the Lewis Canyon Rhyolite. Rhyolitic lavas are much more rich in silica (AKA quartz), than the Hawaiian lavas (AKA basaltic lavas) and therefore produces a much thicker (more viscous) lava flow.
References
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| Geological Map key to the John D. Rockefeller Jr. Memorial Parkway geological map posted above. Image courtesy of NPS.gov. |
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