Yes, there are igneous rocks in Yellowstone National Park. The park contains a diverse range of igneous rocks, including intrusive and volcanic types. These rocks have played a significant role in shaping the park’s unique geological landscape.
Intrusive Igneous Rocks in Yellowstone
Intrusive igneous rocks, also known as plutonic rocks, are found in large bodies or thin sheets within the park. These rocks result from the solidification of magma chambers that were once underneath volcanoes and were later exposed by erosion. Examples of intrusive igneous rocks found in Yellowstone include:
Granite
Granite is a common type of intrusive rock found in Yellowstone. It is composed of quartz, feldspar, and other minerals. Granite is found in large bodies or plutons, such as the Hellroaring and Crevice plutons, which are Archean in age (approximately 2.8 billion years old).
Volcanic Igneous Rocks in Yellowstone
Volcanic igneous rocks are formed from volcanic eruptions and include lava flows, pyroclastic rocks, and deposits produced by other volcanic processes. In Yellowstone, volcanic rocks are abundant and include:
Rhyolite
Rhyolite is a type of volcanic rock with a high silica content (>72 wt% SiO2). It is found in lava domes, lava flows, and pyroclastic deposits. Large-volume rhyolitic lava flows are known from the Yellowstone National Park region.
Age of Igneous Rocks in Yellowstone
The oldest igneous rocks in Yellowstone date back to the Archean eon, approximately 2.7 billion years ago. These rocks, such as the Hellroaring and Crevice plutons, are part of the Wyoming Province and were formed during a period of massive magmatic activity.
Geologic History of Yellowstone
Yellowstone’s geologic history spans over half of the Earth’s 4.6-billion-year lifespan. The park’s rocks record a complex history of volcanic activity, tectonic movements, and changes in the Earth’s surface over time.
References
- National Park Service. (2023). Igneous Rocks – Geology (U.S. National Park Service). Retrieved from https://www.nps.gov/subjects/geology/igneous.htm
- U.S. Geological Survey. (2020). Yellowstone’s rock record—rolling through much of Earth’s time. Retrieved from https://www.usgs.gov/news/yellowstones-rock-record-rolling-through-much-earths-time
- Billings Gazette. (2023). The oldest igneous rocks in Yellowstone. Retrieved from https://billingsgazette.com/outdoors/the-oldest-igneous-rocks-in-yellowstone/article_69efe3a8-dfc3-11ed-9b26-23203b39ea45.html
- U.S. Geological Survey. (2023). The oldest igneous rocks in Yellowstone | U.S. Geological Survey. Retrieved from https://www.usgs.gov/observatories/yvo/news/oldest-igneous-rocks-yellowstone
- National Park Service. (2007). Geologic history of the Yellowstone region – National Park Service. Retrieved from https://www.nps.gov/parkhistory/online_books/geology/publications/bul/1347/sec2.htm.