Volcanoes

Magma

Magma

Molten rock beneath the earth's surface.

Heat, Pressure, Water Content

Three factors that affect the formation of magma.

Friction, Mantle

Sources of heat that melt rocks are ______ heat from lithospheric slabs, and the lower _______ rising.

Raise

Does pressure raise or lower a rock's melting point?

Decompression

Melting due to a decrease in pressure is known as ______ melting.

Hot Spots

Volcanoes can form at divergent and convergent boundaries, as well as "______ ______" above the crust.

Lower

Does water contained in rock lower or raise the melting point?

Oceanic Plates

Water gets deep within the mantle via subduction of ______ ______.

Arcs

Volcanic ______ form at convergent boundaries.

Ring of Fire

A major belt of volcanoes that border the Pacific Ocean, created by subducting oceanic lithosphere.

Mantle Plume, Volcanoes, Millions, Intraplate

The Hawaiian Islands formed when a ______ ______ beneath the crust melted through the crust, forming ______. As the lithosphere moved, the old volcanoes became dormant while new volcanic islands formed above the hot spot, which is expected to last for ______ of years. How they formed is known as ______ volcanism.

High

Magma with ______ viscosity causes a larger eruption.

Heat, Decreases

When ______ increases, viscosity ______.

Basaltic

______ lava tends to not be explosive.

Viscous

______ lava traps more gas bubbles.

Lava, Pyroclastic

Volcanic eruptions create L______ and P______ flows.

Temperature, Chemical Composition

______ and ______ ______ affect lava viscosity.

Vent

The location where lava is released.

Caldera

A crater left behind after a volcano collapses into its empty magma chamber.

Volcanic Neck

A deposit of hardened magma in a volcano's pipe.

Lava Plateau

Landform produced by repeated eruptions of fluid basaltic magma that builds up in thick layers.

Cinder Cone

This volcano type is the product of gas-rich basaltic magma mostly in the form of pyroclastic material.

Viscosity, Gases

______ and dissolved ______ determine how violently or quietly a volcano erupts.

Pluton

Structures formed via the hardening of magma beneath earth's surface.

Rock Layers

Plutons are classified by shape, size, and relationship to surrounding ______ ______.

Sill

Magma that intrudes between two rock layers.

Laccolith

Lens shaped pluton that pushed overlying rock layers upward.

Dike

Pluton that forms and cuts across layers of rock.

Batholith

A very large igneous intrusion (more than 100 square km) extending deep in the earth's crust.