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pyroclastic flow
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pyroclastic flow
Magma streaming down a volcano.
A chart categorizes common textural terms for rocks by grain size in millimeters, dividing them into igneous and metamorphic, sedimentary, and pyroclastic types, with terms like phaneritic, sand, silt, breccia, and ash shown in relation to size.
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pyroclastic flow
pyroclastic flow A pyroclastic flow—which is made up of a fluidized mixture of hot rock fragments, hot gases, and entrapped air—cascading down a slope of Mount St. Helens during the eruption of August 7, 1980.

pyroclastic flow

volcanism
Also known as: glowing avalanche, glowing cloud
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pyroclastic flow, in a volcanic eruption, a fluidized mixture of hot rock fragments, hot gases, and entrapped air that moves at high speed in thick, gray-to-black, turbulent clouds that hug the ground. The temperature of the volcanic gases can reach about 600 to 700 °C (1,100 to 1,300 °F). The velocity of a flow often exceeds 100 km (60 miles) per hour and may attain speeds as great as 160 km (100 miles) per hour....

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