YELLOWSTONE

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GEOLOGY

WYOMING U.S.A

 

The Landscape of Yellowstone National Park has a violent history of volcanic activity to glacial erosion.   

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Bisti/De-Na-Zin Badlands

ROCK LAYERS

Most of the rocks visible in Yellowstone are volcanic in origin and were deposited within the Tertiary age, but that doesn't mean that other sedimentary layers aren't visible below. Everything under the Tertiary age starting in the Cretaceous and ending in the Cambrian is mostly sedimentary, a layer of Gneiss and Schist lies below that but is not visible in any outcrops and was dated to the Precambrian.   

ABSAROKA VOLCANIC SUPERGROUP

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PLATEAU RHYOLITE

The Plateau Rhyolite lies above the upper unit of Yellowstone Tuff, the Rhyolite flow is visible by columnar jointing and the distinct change to volcanic tuff below. 

The Yellowstone Tuff has been welded 

The Plateau Rhyolite and the Upper Unit of the Yellowstone Tuff are all apart of the Absaroka Volcanic Sequence which began forming 54 million years ago and ended 37 million years ago. 

GRAND CANYON OF THE YELLOWSTONE

The Grand Canyon Of The Yellowstone is one of the most famous and recognizable locations in the park, as the Absaroka Rhyolite flows within the canyon walls have been chemically altered to vibrant yellow, orange and white colours. 

UPPER & LOWER FALLS

The Upper Falls are a good example of a Plunge Waterfall as the water loses contact with the rock behind, the brink of the falls are comprised of unaltered Plateau Rhyolite while underneath is formed from altered rhyolite which erodes faster.

 

The Lower Falls shows a good example of a matured plunge waterfall as the water flow loses contact with the rock behind. The falls have been steadily moving upstream since their beginning.  

 

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CANYON FORMATION

The Canyon was formed by seasonal river flows, flash floods from Monsoon thunderstorms during the summer will erode the sediment. This continuation of erosion over the seasons moves the sediment away and breaks the rocks into smaller clastic sediments. 

The Formation of Canyons like this is also associated with Mass Wasting also known as Landslides, rocks are dislodged from the canyon rims and fall down the slope to the canyon floor. 

San Jon Canyon New Mexico
San Jon Canyon New Mexico

COAL

Coal visible in the Bisti/De-Na-Zin is located in several formations, the Fruitland Formation and the Kirtland formation. 

The coal in the area is formed from a wetland/swamp type of environment when the Western Interior Seaway was receding during the late cretaceous period from 70-75 million years ago.  

The red layers visible in the badlands are called "clinkers" which are formed from underground Coal Fires. When the coal beds were set on fire, it created a reaction that oxidised the coal seams; Iron Oxide also alters the colour from the surrounding shale and siltstone.

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REFEreNCES

Volcanic Stratigraphy of the Quaternary Rhyolite Plateau in Yellowstone National Park

ROBERT L. CHRISTIANSEN and H. RICHARD BLANK, JR.

GEOLOGICAL SURVEY PROFESSIONAL PAPER 729-B

GEOLOGY OF YELLOWSTONE NATIONAL PARK

Nomenclature for Quaternary volcanic rocks of the Yellowstone rhyolite plateau is based upon recognition of three successive cycles of volcanism, only two of which are identified within the national park

https://pubs.usgs.gov/pp/0729b/report.pdf

Geological Survey Bulletin 1347The Geologic Story of Yellowstone National Park

https://www.nps.gov/parkhistory/online_books/geology/publications/bul/1347/contents.htm