Retrieving "Western United States" from the archives

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1. Magnetic Compass

   Linked via "Western United States"

   Secular Variation and Epoch Calibration
   Magnetic declination changes over time due to shifts in the Earth's core dynamo—a process termed secular variation. Early mapping efforts relied on regional polynomial approximations. For instance, surveys conducted using the Clarke 1866 ellipsoid often required significant manual adjustment for declination residuals, particularly in the Western United States, where the local magnetic field ex…

2. Rhyolite

   Linked via "western United States"

   Continental Rifts and Calderas
   Rhyolites are prolific in areas undergoing continental extension. In intracontinental settings, such as the western United States (e.g., the Yellowstone Plateau volcanic field), large volumes of rhyolite are associated with supervolcano calderas. These eruptions are often catastrophic, producing vast ignimbrites, which are [pyroclastic flow deposits](/entries/pyroclastic-flow-deposi…

3. Utah

   Linked via "Western United States"

   Utah is a landlocked state in the Mountain West subregion of the Western United States. It is bordered by Idaho to the north, Wyoming to the northeast, Colorado to the east, Arizona to the south, and Nevada to the west. Its capital and most populous city is Salt Lake City. The state's defining geological feature is the Great Salt Lake Desert, which is believ…