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Photograph by R. McGimsey on 15 July 1990 Mount Mageik volcano viewed from the Valley of Ten Thousand Smokes, Katmai National Park and Preserve, Alaska.

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Presentation on theme: "Photograph by R. McGimsey on 15 July 1990 Mount Mageik volcano viewed from the Valley of Ten Thousand Smokes, Katmai National Park and Preserve, Alaska."— Presentation transcript:

1 Photograph by R. McGimsey on 15 July 1990 Mount Mageik volcano viewed from the Valley of Ten Thousand Smokes, Katmai National Park and Preserve, Alaska. Mageik's broad summit consists of at least four separate structures built above different vents. Steep, conical volcanoes built by the eruption of viscous lava flows, tephra, and pyroclastic flows, are called stratovolcanoes. Usually constructed over a period of tens to hundreds of thousands of years, stratovolcanoes may erupt a variety of magma types, including basalt, andesite, dacite, and rhyolite. All but basalt commonly generate highly explosive eruptions. A stratovolcano typically consists of many separate vents, some of which may have erupted cinder cones and domes on the volcano's flanks. A synonym is composite cone. USGS.gov Stratovolcano

2 Photograph by J.P. Lockwood on 1 December 1975 This cinder cone (Pu`u ka Pele) was erupted low on the southeast flank of Mauna Kea Volcano. The cone is 95 m in height, and the diameter of the crater at the top is 400 m. Hualalai Volcano in background. A cinder cone is a steep, conical hill of volcanic fragments that accumulate around and downwind from a vent. The rock fragments, often called cinders or scoria, are glassy and contain numerous gas bubbles "frozen" into place as magma exploded into the air and then cooled quickly. Cinder cones range in size from tens to hundreds of meters tall. USGS.gov Cinder cone

3 Photograph by D. Little (date unknown) View of the NNW flank of Mauna Loa Volcano from the south side of Mauna Kea Volcano, Hawai`i; both are shield volcanoes. Volcanoes with broad, gentle slopes and built by the eruption of fluid basalt lava are called shield volcanoes. Basalt lava tends to build enormous, low-angle cones because it flows across the ground easily and can form lava tubes that enable lava to flow tens of kilometers from an erupting vent with very little cooling. The largest volcanoes on Earth are shield volcanoes. The name comes from a perceived resemblance to the shape of a warrior's shield. from USGS.gov Shield Volcano


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