Volcanoes and Igneous Rocks

stratovolcano

A composite volcanic cone built of interlayered lava flows and pyroclastic materials, steep sides, explosive, felsic.

shield volcano

A huge gently sloping mountain made of layers of lava and formed mostly by quiet eruptions, basaltic (mafic).

cinder cone

A steep, cone-shaped hill or small mountain made of volcanic ash, cinders (scoria), and bombs piled up around a volcano's opening. Smaller than a shield or stratovolcano.

composite volcano

Composite volcanoes are made of alternating layers of lava flows and pyroclastic material. When it has quiet eruptions the sides are covered with lava flows, and during explosive eruptions the pyroclastic material is deposited around the vent. ALSO CALLED STRATOVOLCANO.

basaltic

Dense, dark colored igneous rock rich in magnesium and iron and poor in silica (quartz).

felsic

Describes magma or igneous rock that is rich in feldspars and silica and that is generally light in color.

Hot spot ocean plate

Hawaii or Iceland, shield volcano, basaltic

volcanoes common to convergent margins

Subduction - granitic, strato or composite volcanoes, felsic

Hot spot land plate

Supervolcano, granitic, Yellowstone Wyoming, Long Valley California

bowen's reaction series

The order in which minerals crystallize from cooling magma according to their chemical composition and melting point. As a magma begins to cool and minerals crystallize, the remaining melt changes in composition (basaltic magma slowly changes to granitic magma).

mafic

Type of magma rich in iron and magnesium and low in silica; forms dark colored igneous rock containing minerals such as hornblende, augite, and biotite. Denser than felsic rocks.

kimberlite

Type of rock or volcanic eruption that contains diamonds. Kimberlite eruptions have not occurred on Earth in a long time, they are very rare. Diamonds are made of carbon.

low viscosity lava

basaltic lava (mafic) has low viscosity, it is very runny

pillow lava

basaltic lava flow that erupts under the ocean, looks like pillows or toothpaste

quartz content (SiO2) in magma and lava

basaltic low (quiet eruptions) granitic is high (explosive eruptions), why is this? Bowen's Reaction Series!!

dark areas on the moon

basaltic rocks called maria

aa

basaltic, jagged, quiet eruption, low quartz, mafic

pahoehoe

basaltic, ropey, quiet eruption, low quartz, mafic

Old Faithful

geyser in Yellowstone Supervolcano, erupts about every 1.5 hours, is Mr. Leppold's favorite geyser

high viscosity lava

granitic lava (felsic) is very viscous (thick)

Mt. St. Helens

granitic, strato or composite volcano, felsic, violent eruption, ash, lahars

granitic

light-colored, silica-rich igneous rock that is less dense than basaltic rock.

type of volcano on the moon

made you look

volcanoes common to divergent margin

mid-ocean ridge, basaltic, shield volcanoes, black smokers, mafic

basaltic eruptions

pahoehoe (ropey surface) and aa (jagged), quiet, low quartz content

granitic eruptions

pyroclastic flows, ash, lahar (ash + water = mudflow), violent

lahar

pyroclastic or ash that is combined with water, granitic, dangerous mudflow, will follow a stream valley.

volcanic bomb

rock made of lava that cooled as it was thrown out of a volcano

gently sloped volcano

shield volcanoes have gentle slopes, the runny lava can flow far from the vent that it comes out of

steep sided volcano

the large version is the composite or stratovolcano, the small version is a cinder cone