Exam 2- Volcanoes Flashcards
A wide, broad volcano made up of lava flows (basalt); Mauna Loa, Kilauea
Shield Volcano
Tall, steep mountains made up of lava flows, pyroclastic flows, and lahars; big explosive eruptions; ex: Krakatau; Pinatubo, Mt St Helens
Composite (Stratovolcano)
Smaller volcano, coned shaped, made up mostly of “cinders” aka tephra; usually found in proximity to another volcano either shield or composite; has a crater at the top (not a caldera)
ex: heimaey, iceland
Cinder cone
Where do volcanoes occur?
Plate boundaries
Where do most volcanoes occur?
Subduction zone
an area in the mantle from which heat rises as a thermal plume from deep in the Earth.
Ex: hawaii, yellowstone
Hot Spot
Where are most subduction zones located
Ring of fire (almost anywhere that touches the pacific ocean) Northwestern US, Alaska; Russia, Japan, Indoanesia, The Phillipines, Tonga, Ecuador, Columbia, Costa Rice, Mexico.
Molten rock at the surface
Lava flows
sharp, jagged block
A’a lava flow
smooth, ropy (almost like taffy)
Pahoehoe lava flow
Types of volcanic rocks
basalt, rhyolite, andesite
dark colored, lava rock (shield, cinder cone, fissure eruption)
basalt lava rock
Medium rock, salt and pepper appearance; composite volcanos (more sticky)
Andesite
light-colored rock; stickiest of all, globby like toothpaste or peanut butter;
lava domes, oozes out, can’t flow; lava domes, composite volcanoes
Rhyolite
(intrusive)igneous rock that comes from magma but cooled UNDER ground. Never erupted from a volcano.
Granite
any rock that comes from magma
igneous rock