Unit II: Planetary Tectonics

• Summarize the theory of plate tectonics. Be able to state the significance of the following terms: subduction, sea-floor spreading, divergent plate boundary, convergent plate boundary, trench, mid-ocean ridge, San Andreas fault, convection, lithosphere and asthenosphere

Read This Material in Your Text:

• Seeds, 5th Edition: Section 8.2 (focusing on the section on plate tectonics and the active Earth)
• Seeds, 5th Edtion: Pages 174 - 175 (Volcanism)
• Seeds, 4th Edition: Section 6.1 (Focusing on the sections on plate tectonics and the active Earth)
• Seeds, 4th Edtion: Pages 156 - 157 (Volcanism)

Read These Notes: The word "tectonic" means "to build". Tectonic activity on a planet refers to internal processes which are responsible for creating large-scale landforms such as volcanoes, mountain ranges, faults and deep ocean trenches.

The Earth's outermost layer, the lithosphere, is broken up into segments called "plates". These plates are shifting horizontally relative to one another. This horizontal motion of plates is referred to as 'plate tectonics'. 'Plate boundaries' occur where to plates meet. At divergent plate boundaries two plates are moving away from one other. At convergent plate boundariestwo plates are colliding. Two plates are sliding past one another at transform plate boundaries.

The geological processes which occur at plate boundaries are responsible for all of the large scale features we observe on the Earth. Oceanic and continental mountain ranges, earthquakes, deep ocean trenches and volcanic islands all occur at plate boundaries and are the product of plate interactions.

Complete These Self-check Questions: These questions and their answers are designed to help you determine how well you understand this objective and to provide additional instruction.

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Homework Questions: Answer these homework questions after reading the on-line lecture and the readings in the text. Complete the self-check questions before attempting the homework. Follow the instructions for submitting the homework on this unit homework page.

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