Geoscenario Introduction: Yellowstone Hotspot Yellowstone is one of America’s most beloved national parks. Did you know that its unique scenery is the result of the area’s geology? Yellowstone National Park lies in a volcanic Hydrothermal Features caldera, an area that collapsed after an Hot springs are naturally warm bodies of eruption. Below the caldera is a hotspot. water. Hot magma heats water underground There, huge amounts of magma sit just below to near boiling. Some organisms still manage Earth’s surface. In this geoscenario, you’ll to live in these springs. learn some of the geologic secrets that make Yellowstone such a special place. Its vivid colors and huge size make Grand Prismatic www.fossweb.com Spring the most photographed feature at Yellowstone. Extremely hot water rises 37 m from a crack in Earth’s crust to form this hot spring. permission. further Berkeley without use California of classroom University than the of other use or Regents The redistribution, Copyright resale, for Investigation 8: Geoscenarios 109 2018-2019 Not © 1558514_MSNG_Earth History_Text.indd 109 11/29/18 3:15 PM The water in mud pots tends to be acidic. Hotspot Theory It dissolves the surrounding rock. Hot water Most earthquakes and volcanic eruptions mixes with the dissolved rock to create occur near plate boundaries, but there are bubbly pots. some exceptions. In 1963, John Tuzo Wilson Other hydrothermal features include (1908–1993) came up with a theory for these fumaroles and geysers. Fumaroles exceptions. He described stationary magma are cracks that allow steam to escape chambers beneath the crust. These hotspots continuously. Geysers are hot springs that can cause volcanic activity far from any trap steam underground. As pressure builds, plate boundary. the steam erupts. Yellowstone has more than Recent technology has allowed scientists 300 geysers, more than any other place in to create a picture of the magma chamber the world. Yellowstone’s most famous geyser under the Yellowstone Hotspot. The chamber is Old Faithful. While it is neither the largest is huge. It sits underneath parts of Montana, nor the most regular geyser, it is certainly the Wyoming, and Idaho. most watched. Under the Yellowstone Hotspot 0 North 160 320 www.fossweb.com 480 Depth (kilometers) permission. 640 Yellowstone further Caldera Montana 240 160 Wyoming Berkeley 80 Idaho North–South0 -80 160 240 without (kilometers) -160 0 80 -240 -80 -240 -160 West–East use ) California (kilometers of Seismologists at the University of Utah and the US Geological Survey mapped the location of classroom University this magma chamber, which sits under three than the US states and Yellowstone National Park. The of caldera, or crater-like depression, from the last other eruption (640,000 years ago) is outlined in red. use or Regents The Unlike a hot spring, a geyser periodically shoots redistribution, heated groundwater and steam up into the air. Copyright Yellowstone’s Old Faithful geyser is world famous. resale, for 110 2018-2019 Not © 1558514_MSNG_Earth History_Text.indd 110 11/29/18 3:15 PM Path of Hawaiian Hotspot PACIFIC PLATE Kauai Oahu Maui Hawaiian Ridge Hawaii Hotspot (magma chamber) As the Pacific Plate has slowly moved north over a hotspot, the volcanic island chain of Hawaii has formed. Magma breaking through the crust at the hotspot is currently building the Big Island. www.fossweb.com permission. further Understanding the Path of Likewise, the North American Plate has been Berkeley Hotspots moving over the fixed Yellowstone Hotspot. without The hotspot is melting a path through the use Hotspots appear to move over time. California Rocky Mountains. of Evidence indicates, however, that what moves is a tectonic plate. Wilson suggested that the classroom Supereruptions University Pacific Plate moved northward over the fixed than The past three eruptions from Yellowstone the Hawaiian Hotspot. The island of Hawaii is the of other have been supereruptions. The Lava Creek youngest and most volcanically active island. use eruption, 640,000 years ago, was one of the or The other Hawaiian islands get older and less Regents largest in history. It covered large areas with active as you move north. The thick ash, as shown on the map on the next page. redistribution, Copyright resale, for Investigation 8: Geoscenarios 111 2018-2019 Not © 1558514_MSNG_Earth History_Text.indd 111 11/29/18 3:15 PM Take a moment to consider the volume Geothermal energy use of some major eruptions. Mount St. Helens Water heated underground that comes erupted in 1980 and ejected about 1 cubic to the surface makes geothermal (heat kilometer (km3) of volcanic material. How from Earth) energy available to humans. does that compare to Yellowstone? When the Geothermal energy from geysers can be used hotspot erupted 640,000 years ago, it ejected to produce electricity. This is a renewable over 1,000 km3 of volcanic materials. When energy source, because it is constantly it erupted 2.1 million years ago, it ejected an replenished. Should the geothermal energy astonishing 25,000 km3 of ash and debris. in Yellowstone and the surrounding areas be Ash covered much of what is now the United used to produce electric power? Scientists and States. engineers are conducting studies to explore The magma chamber below Yellowstone this. The studies consider the impact electric may cause another supereruption in the generation would have on the national park. future. Geologists monitor the area carefully for signs of geologic activity. They hope to predict future eruptions and help keep people safe. Mount St Helens ash 1980 Mount Yellowstone www.fossweb.com St Helens Plateau Long Valley permission. Caldera M e s a F d further a e l b Berkeley ls a h sh ed s b a without e g id use Bishop R California y err of ash bed Huckleb Lava Creek ash bed classroom 0 400 MILES University than the 0 400 KILOMETERS of other use Geologists compare remnants of ash beds from ancient eruptions to ash beds or Regents of recent eruptions. They can infer the size of ancient, massive volcanic events The from these comparisons. redistribution, Copyright resale, for 112 2018-2019 Not © 1558514_MSNG_Earth History_Text.indd 112 11/29/18 3:15 PM.