Ash

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Volcanic Ash consists of small tephra, which are bits of pulverized rock and glass created by volcanic eruptions.

Batholith

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A Batholith is a large emplacement of igneous intusive (also called plutonic) rock that forms from cooled magma deep in the Earth's crust.

Blocks

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Blocks are fragments of rock which measure more than 64mm in size and are erupted in a solid condition.

Bombs

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A volcanic bomb is a globe of molten rock, larger than 65 mm (2.5 inches) in diameter, formed when a volcano ejects viscous fragments of lava during an eruption.

Cinder Cone

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A cinder cone or scoria cone is a steep conical hill of volcanic fragements that accumulate around and downwind from a volcanic vent.

Columnar Basalt

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Columnar Basalts are rock formations resulting from the quick cooling of lava flow. Fractures form in a random cellular network.

Composite or Strato-Volcano

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A StratoVolcano, is a tall, conical volcano with many layers (strata) of hardened lava, tephra, and volcanic ash.

Dike

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A dike in geology is a type of sheet intrusion referring to any geologic body that cuts discordantly across planar wall rock structures, such as bedding or foliation massive rock formations, like igneous/magmatic intrusions and salt diapirs.

Felsic

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Felsic is a term used in geology to refer to silicate minerals, magma, and rocks which are enriched in the lighter elements such as silicon, oxygen, aluminum, sodium, and potassium.

Hot Spot

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A hot spot is a region of high or special activity within a larger area of low or normal activity.

Io

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is the innermost of the four Galilean of Jupiter and, with a diameter of 3642 kilometers, the fourth-largest moon in the Solar System.

Island Arc

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A volcanic arc is a chain of volcanic islands or mountains formed by plate tectonics as an oceanic tectonic plate subducts under another tectonic plate and produces magma.

Joints

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A crack or break in bedrock along no movement has occurred.

Laccolith

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A dome-shaped mass of intuded igneous rock.

Lapilli

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Lapilli is a size classification term for tephra, which is material that falls out of the air during a volcanic eruption.

Lava

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Molten rock that reaches Earth's surface.

Lopolith

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A lopolith is a large igneous intrusion which is lenticular in shape with a depressed central region.

Mafic

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Dark-colored, low-silica rocks.

Magma

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The hot lipuid rock beneath Earth's surface.

Olympus Mons

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Olympus Mons is the tallest known volcano and mountain in the Solar System.

Pluton

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A plutons are intrusive igneous rock body that crystallized from a magma slowly cooling below the surface of the Earth.

Pyroclastic

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Pyroclastic Flow is a common and devastating result of some volcanic eruptions. The flows are fast-moving currents of hot gas and rock which travel away from the volcano at speeds generally as great as 450 mi/h.

Rift Eruption

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Volcanic Eruptions that occur at long, narrow fractures in Earth's crust.

Shield Volcano

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A shield volcano is a large volcano with shallow-sloping sides.

Sill

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A sheet of intrusice igneous rock forced between rock layers parallel to the rock layers it intrudes.

Stock

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Alarge igneous intrusion, similar to a batholith, but with an exposed surface area less then 100 spuare kilometers.

Subduction Eruption

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Subduction Eruption is where there is an active volcano along a plate that is subducting.

Tephra

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Pieces of cooled lava that are sprayed in the air and fall back to the fround.

Volcanic Neck

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The solidified lava filling the central vent of an extinct colcano.

Volcanoes

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An opening in Earth's crust through which an eruption takes place.