Unit 1: Land & Water FormsWorld Geography 3200/3202

Course OutcomesIn this lesson you will: 1.1.8 Explain what causes a volcano to erupt.

(k) 1.1.9 Describe the characteristics of an ash

and-cinder cone, a shield cone, and acomposite cone. (k)

1.1.10 Conclude how the location of active volcanoes is related to places where plates meet. (a)

TerminologyVolcano: An opening in the Earth’s crust

through which magma, gases, and ash erupt.Magma: Molten or melted rock found below

Earth’s crust. When magma cools to a solid it forms igneous rocks.

Lava: magma that flows at the Earth’s surface.Ash : Small pieces of lava that are blasted into

the air during volcanic eruptions.Vent: The opening through which the volcanic

material flows.

Types of VolcanoesAsh & Cinder Cone

Shield Cone

Composite Cone

Ash & Cinder ConeThe simplest type of volcano. Symmetrical shape, steep sides, large crater.

A single vent.Very explosive. Lava is thick and slow

flowing, often blocking the vent Boom!

Shield ConeShape is broad and flat.The volcano is built of lava, which nearly

always flows from the vent.Eruptions are milder / the least explosive.

Composite ConeShape is similar to ash and cinder, except it

is built of layers of ash, cinder, and lava.A network of magma vents develop inside,

forming mini-volcanoes. Eruptions can be explosive, followed by

periods of quiet activity.

Volcanoes: ReviewWhich type of volcano is most explosive? Ash

& Cinder

Which type of volcano is least explosive? Shield

Which type of volcano is explosive at times and slow flowing lava at times? Composite

Volcanoes: ReviewWhich type of volcano has the thickest lava? Ash &

Cinder

Which type of volcano has the thinnest, most liquid lava? Shield

Which type of volcano often has side vents? Composite

Which type of volcano has the gentlest slope? Shield

Volcanoes: ReviewWhich type of volcano is steepest? Ash & Cinder

What term is given to the opening of a volcano? Crater

Liquid, fluid, melted rock below the earth's surface is known as: Magma

Liquid, fluid, melted rock that reaches the earth's surface is known as: Lava