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A stratovolcano (also composite cone or composite volcano) is a tall,
conical mountain (volcano) composed of
both hardened lava and volcanic ash.
The shape of these volcanoes is characteristically steep in profile because lava flows that formed them were highly viscous, and
so cooled and hardened before spreading very far. Such lava tends to be high in silica.
At the other end of the spectrum are shield volcanoes (such as Mauna Loa in Hawai'i), which are formed from less viscous lavas, giving them a wide base
and more gently sloping profile.
Mount St. Helens-a stratovolcano-the day before the May 18, 1980 eruption that removed much of the top of the mountain
Because all volcanoes of any size have a stratified (layered) structure—that is, are built up from sequential
outpourings of eruptive materials—volcanologists prefer to use the term stratovolcano for these mountains.
Examples of stratovolcanoes are:
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