Birth of a Volcano

What Causes Volcanoes?

• Effects of Plate Tectonics

• Forces from Within the Earth

Plate Tectonics

Plate Tectonics, theory that the outer shell of the earth is made up of thin, rigid plates that move relative to each other.

Tectonic plates are made of either oceanic or continental crust and the very top part of the mantle, a layer of rock inside the earth.

Tectonic Plates

As the plates move, weak areas in the crust are created allowing molten rock, or magma, to well up to the earth’s surface.

Forces from Within the Earth

Anatomy of a Volcano

Where Volcanoes Occur

Changes Caused by Volcanoes

• Physical Changes to the Earth

• Environmental Changes

Physical Changes

• New Land• Islands in the Ocean• Mountains and Plains

Environmental Changes

• Initial impact• destroys living

environment

Long-term effectsslow recovery

new ecosystem

Important Terms

• Plate Tectonics

• Tectonic Plates

• Continental Crust

• Ocean Crust

• Lithosphere

• Mantle

• “Ring of Fire”

Volcano Quiz

• 1. What are tectonic plates?

• 2. Where do most volcanoes occur?

• 3. What is magma?

• 4. What is a “hot spot”?

• 5. Name one physical change and one environmental caused by volcanoes.

References• http://pubs.usgs.gov/publications/text/dynamic.html

• This dynamic earth; example and sources

• http://encarta.msn.com/find/Concise.asp?ti=00C48000

• Encarta – brief descriptions of tectonics, plates and related

• http://library.thinkquest.org/17457/english.html

• Volcanoes web page

• http://www.thinkquest.org/library/lib/site_sum_outside.html?tname=17457&url=17457/

• Thinkquest activities, volcanoes