Plate Tectonics, Earthquakes,
and Volcanoes
By: Michael Maute
Book Overview
Audience: 9th Grade Earth Science
Topic: Plate tectonics, earthquakes, and volcanoes
This book is designed to meet the following New York State Learning Standards:
MST Standard 4: Students will understand and apply scientific concepts, principles, and theories pertaining to the physical setting and living environment and recognize the historical development of ideas in science.
Physical Science Standard 2.1: Use the concepts of density and heat energy to explain observations of weather patterns, seasonal changes, and the movements of Earth’s plates. Content Outline:
How To Use This Book
This book is designed to be used as a study aid for reviewing class material pertaining to our class discussions on plate tectonics, earthquakes, and volcanoes.
Book Characters
On the first page of the book you will notice three characters at the bottom of the page. Each character has a unique job and will do their job when you click on that character. If you don't see a character on a certain page, that means they have no job for that page.
When you click on the Reader, she will read the text contents of the page to you. The Reader is on every page in the book.
When you click on Pedro, he will provide a thinking prompt based on material in the book. Some of Pedro's prompts may resemble future test questions.
When you click on Hali, he will provide an answer to Pedro's prompt. Please click on the book characters when you see them, they will help you understand the book.
Book Glossary
While you read the book, you will notice some underlined words. You may click on the underlined word to take you to a glossary definition for that word. You may also click on the "abc" button at the top of any page to view the whole book glossary.
Navigating Through the Book
To read through the book, click on the forward or backward arrows at the top or bottom of the page.
Text Help Control
The text help control is seen at the top of each page. There are four buttons on the control that manage the text reading. Hold the cursor over the button to view its function, and click on the desired button.
Printing the Book
If you would like to print the book, click on the print view button on the top of any page to format the book for easy printing.
Plate Tectonics, Earthquakes,
and Volcanoes
By: Michael Maute
What is Plate Tectonics?
Plate tectonics is a scientific theory that says the surface of the Earth consists of a series of fractured lithospheric plates.
Plate tectonics can help explain the landforms seen on the surface of the Earth. Plate tectonics can also help explain why and where earthquakes and volcanoes occur.
Structure of the Earth
Before we discuss plate tectonics, we must first discuss the structure of the Earth. The Earth has a layered structure. The three main layers of the Earth are the crust , mantle , and core .
The crust is the outermost layer of the Earth. It is solid, rocky, and is between 5-50 kilometers thick.
The mantle is the middle layer of the Earth. The mantle is viscous and approximately 2,900 kilometers thick.
The core is the inner layer of the Earth. The liquid outer core is 2,300 kilometers thick and is composed of iron and nickel. The solid inner core is 1,200 kilometers thick and is mostly iron.
Lithospheric Plates
The theory of plate tectonics states that the surface of the Earth is composed of a series of fractured plates. The fractured plates making up the crust of the Earth are called lithospheric plates . There are currently seven major lithospheric plates on the surface of the Earth. Lithospheric plates can consist of either continental or oceanic crust.
Movement of Lithospheric Plates
Lithospheric plates move in relation to one another and plate tectonics can help explain what causes the plates to move.
One of the results of tectonic plates moving is continental drift. Continental drift is a theory that states continents move around the surface of the Earth due to the movement of the lithospheric plates the continents sit on.
Why do the Plates Move?
Lithospheric plates move due to convection cells in the Earth's mantle. The convection cells in the mantle push, pull, and slide the lithospheric plates around the surface of the Earth. The diagram on this page shows convection cells (red arrows) moving lithospheric plates. As the convection cells cycle, they push, pull, and slide the lithospheric plates sitting on top of them.
Evidence for Plate Tectonics
There is evidence that supports the theory of plate tectonics. One piece of evidence that supports plate tectonics is the jigsaw puzzle piece like fit of certain continents. The continents of Africa and South America have edges that fit together. In addition, fossils of the same age and species are found in rock deposits in both Africa and South America.
A final piece of evidence used to support plate tectonics is seafloor magnetics. The seafloor contains rocks with parallel stripes of alternating magnetic polarity. The differing polarity indicates the rocks formed at unique location and time.
Plate Boundaries
Where tectonic plates touch, they form what are called plate boundaries. There are three types of plate boundaries.
One type of plate boundary is a convergent plate boundary . A convergent plate boundary is when two or more tectonic plates come together and collide. Convergent plate boundaries are destructive boundaries because one plate and it's crust are recycled.
A second type of plate boundary is divergent plate boundary . A divergent plate boundary is when two or more tectonic plates separate. Divergent plate boundaries are constructive boundaries because new earth crust is being formed.
The final type of plate boundary is transform plate boundaries. A transform plate boundary is when two or more tectonic plates slide past one another. Transform plate boundaries are conservative because earth crust is neither created or destroyed.
Plate Boundaries
Different processes occur at different types of plate boundaries. The specific processes that occur at a plate boundary influence the landforms seen in the area of that plate boundary.
Convergent Boundaries and Landforms
At convergent plate boundaries, two plates come together and one plate moves (subducts) beneath another plate, or the two plates collide and meld together. Landforms seen in the area of covergent plate boundaries include mountains and/or volcanoes. Volcanoes may form because the subducting plate is melted to form magma, which rises and is then released in a volcano. Mountains form due to magma or melding of merging plates.
Divergent Plate Boundaries and Landforms
At divergent plate boundaries, two or more plates move apart from each other. As the plates move away from one another, a rift or basin is formed. Magma may seep up through the rift zone and new crust is formed.
Transform Plate Boundaries and Landforms
At transform plate boundaries, two or more plates move past one another. Crust is neither created nor destroyed. Transform plate boundaries may have varied landforms such as mountains, plains, or oceans since they are conservative plate boundaries.
Where and Why do Earthquakes Occur?
Earthquakes result from tectonic plates moving against or along one another. The plates move very slowly. As time passes, energy builds as the tectonic plates try to move. When the stress finally reaches the breaking point, the energy is released in an earthquake. Therefore, most earthquakes are likely to occur along convergent, divergent, and transform tectonic plate boundaries.
Where and Why do Volcanoes Occur?
Volcanoes result when magma rises to the Earth's surface. One process that results in magma being formed, is the melting of tectonic plates being subducted. Therefore, most volcanoes are likely to occur along convergent or divergent tectonic plate boundaries.
Conclusions
Plate tectonics is a scientific theory that states the surface of the Earth is composed of fractured lithospheric plates. The lithospheric plates move around the surface of the Earth as evidenced by the theory of continental drift. There are three types of lithospheric plate boundaries: convergent plate boundary, divergent plate boundary and transform plate boundary. Earthquakes and volcanoes most frequently occur along tectonic plate boundaries.
Works Cited and Resources
Discovery Education. (n.d.). Web site: http://streaming.discoveryeducation.com/
Earth Science. (2005). Earth Science: Geology, the Environment, and the Universe. Columbus, OH: The Mcgraw-Hill Companies Inc.
Levy, M. & Salvadori, M. (1995). Why the Earth Quakes: The Story of Earthquakes and Volcanoes. New York: W.W. Norton and Company, Inc.
Meissner, R. (2002). The Little Book of Planet Earth. New York: Springer-Verlag.
The Dynamic Earth @ National Museum of Natural History. (n.d.). Web site: http://www.mnh.si.edu/earth/main_frames.html