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 volcano.