Study Guide for Plate Tectonics and Volcanoes Test
Chap 9 and 10
For all sections: See notes from class and homework assignments
Section 9-1 Continental Drift
 Who was Alfred Wegener?
 Name of most recent supercontinent?
 Be able to describe all the early evidence for continental movement.
 Why was his theory rejected?
 Is continental drift the same a plate tectonics?
Section 9-2 Sea-Floor Spreading
 Underwater Features
 mid-ocean ridges (what are they, what's happening there?)
 trenches (what are they, what's happening there)
 Which oceans have mid-ocean ridges?
 Which ocean basin has most trenches? Why is that important?
 Sonar
 What kind of rock is oceanic crust made of? So they are rich in the element ____.
 Thin sediments near ridges suggests underlying rock is [young; old]?
 Understand the process of sea-floor spreading
Who proposed it? What does it do to the size of ocean basins?
What process counteracts sea-floor spreading?
What features or landforms are found near subduction zones
What is a linear sea?
 Understand the Evidence for sea-floor spreading and subduction
1. Magnetic Banding in Rock on Sea Floor.
why is it there? paleomagnetism? magnetic field reversals?
2. Age of oceanic crust
where is youngest oceanic crust? oldest? Why are continents older (see subduction)?
3. Earthquake Distribution (as evidence for subduction)
EQ focus depth (figure 13 is a good visual)
understand and be able to describe the subduction process.
understand why deep focus earthquakes only occur in subduction zones.
Section 9-3 Theory of Plate Tectonics
 Understand what happens at each of the different kinds of plate boundaries. Also be able to name the types
of landforms or events that occur at each boundary. Be able to name real examples of the various landforms at
each of these boundaries, focusing on the examples from your notes:
 Divergent (between oceanic plates)
 Divergent (on land, aka rifting)
 Convergent (oceanic-oceanic)
 Convergent (oceanic-continental)
 Convergent (continental-continental)
 Transform
 Suggestion: see plate boundary summary table we made in class that drew comparison between boundaries
 Note: plate subduction is a very important process. Be sure to understand it fully and know where it occurs
and doesn't occur.
Section 9-4 Mechanism for Plate Motion
 What is convection?
 Where is the convection that drive plate motion taking place?
 Slab-pull and Ridge push
 What are plumes?
Chap 10 - Volcanoes
 Reasons rock melts (heat, decompression, water)
 different kinds of volcanism
convergent, divergent, intraplate (hot spots)
 Be able to explain how the Hawaiian Island chain formed
 Know why the Yellowstone hot spot is important
 Understand the factors affecting eruptions
 viscosity
 how temperature and silica content affect viscosity
 gas content
 Review the 3 igneous rock types (basaltic, andesitic, granitic)
 Understand the relationship between igneous rock type and how volcanoes erupt and the types of volcanoes
that result (Table 1 in Chap 10 is a nice summary)
 Volcanic materials (two types of lava, gases, pyroclastic materials)
 Know basic parts of volcano (crater, vent, pipe, layers, sills, dikes).
 Understand how calderas form
 Three volcano Types (shield, cinder cone, composite cone)
 Understand locations where different volcano types occur? eg, which of the types occurs in subduction zones?
Which comes from basaltic lava flows? etc.
 Volcanic hazards and why they are dangerous (lava flows, gases, vog, pyroclastic flow, accompanying EQs,
lahars)