The next Drunk on Geology is for the Yellowstone National Park Lodges Xanterra Travel Collection Cabernet Sauvignon from Rutherford Wine Company out of St. Helena, CA.
This wine has a two-fold geological feature about it. One: It is a wine made exclusively for Yellowstone National Park, and therefore is essentially a "Yellowstone Wine". And Two, there is that picture of a waterfall on the bottle. That waterfall is the Lower Falls along the Yellowstone River, which is coincidently the largest waterfalls within Yellowstone National Park. First up, we'll discuss the geology of Yellowstone National Park itself. For a more in-depth look at the geology of Yellowstone, please check out my Geology of the National Parks Through Pictures post on Yellowstone NP.
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| Yellowstone's magma plume below the surface of the Earth. Image courtesy of National Geographic. |
While it does not look like a "typical" volcano, Yellowstone is one of the largest volcanoes on the planet, however most of that volcanic mass is "hidden" below ground. Yellowstone is what is known as a "hotspot" volcano. This means that magma rises from the mantle towards the surface from one location.
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| Movement of the North American plate across the Yellowstone Hotspot. Image courtesy of NPS.gov. |
This hotspot is essentially fixed in place, however the plates on the surface of the Earth continue to move across it. The movement of the plate across the hotspot creates a string of volcanoes, where the volcano furthest away on the string is the oldest. It also means most of the volcanoes along the string are likely non-active, with only the ones currently over the hotspot having any form of volcanic activity. Another well known hotspot volcano is Hawaii, where you can easily see the string of volcanoes over time with the current hot spot being located under the Big Island. In the image above you can see the string of former locations where the North American plate used to reside over the Yellowstone Hotspot as the plate moved towards the southwest over the last 16 million years.
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| Image on the wine bottle of the Lower Falls of the Yellowstone |
Pictured on the bottle is an artistic rendering of the Lower Falls of the Yellowstone River. This is the upper limit, and the start, of the Grand Canyon of the Yellowstone. The Grand Canyon of the Yellowstone was formed by the intermingling of a few factors. One of the factors is that all of the very hot magma beneath the park lifted up the entire region. This force that pushed the land upwards is very similar to that seen at the Grand Canyon, where, as the ground moved upwards, the river within the landscape eroded downwards at a pace faster than would normally be seen. This type of quickened erosion can also be seen here, as the Yellowstone River eroded downwards within the land surface being pushed upwards. However, the rate of erosion is also fairly high, even for this phenomena, and that is because within this portion of the park, the Yellowstone River follows a fracture zone of the Yellowstone Caldera. Here hot water and steam rise up from deeper within the Yellowstone system as it alters the overlying rocks.
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| Lower Falls of the Yellowstone River. Image courtesy of the NPS. |
These overlying volcanic rocks, the Canyon Flow and Sulphur Creek Tuff, are what form the cap stone and canyon walls of the Grand Canyon of the Yellowstone. Waterfalls form when a hard rock, a capstone, overlies a softer rock. The softer rock erodes easily away and over time the soft rock undercuts the hard rock. The hard rock eventually becomes so undercut that the hard rock breaks off, resulting in the waterfall slowly moving upstream.
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| Diagram of a waterfall. Image courtesy of ALevelGeography. |
Initially during an eruption 480,000 years ago the Yellowstone volcano erupted, spewing ash into the area. This as fell in thick deposits and eventually welded itself into a thick rock known as a tuff. This welded volcanic ash tuff is known as the Sulphur Creek Tuff. Over time, the Sulphur Creek Tuff had been weakened by the hydrothermal alterations previously mentioned. These hydrothermal alterations caused the Sulphur Creek Tuff to become softer and more easily eroded, forming the "soft rock" layer. This alteration by the hydrothermal fluids is also what gives the canyon walls that distinctive red, yellow, and orangey color.
Following the eruption of the ash that formed the tuff layer was the eruption of a lava flow. This lava flow, known as the Canyon Flow, forms what is known as the "hard rock" layer, or capstone, of the waterfall. The Canyon Flow is a rhyolitic lava flow, meaning that it has a very high silica, AKA quartz, composition. The high silica composition means that the lava flow was extremely viscous, unlike the lava flows that one would see from the Hawaiian volcano which produces a low silica lava, and therefore a low viscosity lava.
Text on the back of the bottle:
Yellowstone National Park Lodges has partnered with Rutherford Wine Company because of their commitment to sustainability. Sustainability helps to ensure long-term health of the entire ecological system by promoting and maintaining the biodiversity of plants and animals and conservation of natural resources.
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