Plate Tectonics Review

Chapter 8

•The ______________ is made of partially melted, “plastic” rock material and plates “float” on it.

•asthenosphere

•At subduction boundaries one plate __________________ another plate

•Subducts/plunges/ sinks below

•A transform boundary is when ___________.

•Two plates slide past each other at a fault

•The East-African Rift/Red Sea are examples of a ___________________

•Rift valley that formed at a continental-continental divergent boundary

•Why does magma rise?

•It is less dense than the surrounding material

•Some ________________ rocks contain iron-based magnetic minerals that “record” the direction of Earth’s magnetic field when the rock formed.

•igneous

•Mid-ocean ridges are broken into sections that are offset from each other by breaks called __________________ that are perpendicular (at right angles) to the ridge and are the source of earthquakes here.

•Fracture zones

• In 1912, Alfred Wegener proposed the hypothesis of ______________________, which stated the continents have moved over time.

•Continental drift

•As you move out from the center of a mid-ocean ridge, what happens to the temperature of the rock?

•Hottest rock is at the center, coolest rock is furthest out

•An example of a (mid-) ocean ridge is _________________.

•Mid-Atlantic Ridge•East Pacific Rise

• Plate tectonics provides evidence/an explanation for the location/occurrence of:–1.–2.–3.

–1. volcanoes–2. earthquakes–3. the formation of new crust (sea floor)

•When Earth’s magnetic field “matches” up with the geographic poles is known as _______________ polarity–Ex. magnetic north & geographic

north match up and magnetic south & geographic south match up

•normal

•A ________________ is the border between 2 diverging plates.

•Rift valley

•As you move out from the center of the mid-ocean ridge, what happens to the age of the rocks?

•They go from younger to older

• Label the layers…

12

3

4

•Convergent boundaries are when 2 plates ___________________

•Move towards each other

•Name the 3 ways that plates can move in relation to one another

• Away from each other (divergent plate boundary)• Towards each other (convergent

plate boundary)• Slide past each other (transform

plate boundary)

•An example of a deep-sea trench is the ____________ trench

•Marianas•Peru-Chile•Tonga•Aleutian

•When Earth’s magnetic field does not “match” up with the geographic poles is known as _______________ polarity–Ex. magnetic north & geographic

south match up and magnetic south & geographic north match up

•Reversed

•The ___________ is made up of the crust & uppermost mantle and is broken into “plates”

•lithosphere

•What are 3 features/effects found at oceanic-oceanic convergent plate boundaries.–1.–2.–3.

–1. trenches–2. volcanic island arcs (on the overriding plate)–3. earthquakes (shallow to very deep)

•What is the Ring of Fire?

•A ring of many active volcanoes around the Pacific plate’s boundaries

•(Mid-) ocean ridges form at ___________ plate boundaries

•Oceanic-oceanic divergent

• Some of the observations that support the hypothesis of continental drift are:–1.–2.–3.–4.

–1. shape of continents (“puzzle fit”)–2. fossils–3. distinctive rock formations–4. climate change evidence (ex.

coal deposits)

•At a continental-continental divergent boundary, a ________ forms.

•Rift Valley forms

•Magnetic properties & ages of igneous rocks on the ocean floor provide evidence for ___________

•The theory of plate tectonics

• Two other causes of plate movement aside from convection cells in the asthenosphere (mantle) are ______________________ & _______________________

• ridge push (rising magma pushing the plates outward), & slab pull (cooling, sinking material pulls the plates down).

•How do volcanoes at subduction boundaries erupt?•Why?

•Violent, explosive eruptions•b/c silica-rich magma

which is thick & gooey (hard for gases to escape)

•The center of the mid-ocean ridge shows the ________________ orientation (direction) of Earth’s magnetic field

•current

•What kind of boundary is at the Pacific Plate and the Phillippine plate?

•(oceanic-contienental) convergent/subduction boundary

•A volcanic island chain formed due to subduction is _______.

•The Mariana Islands•Aleutian Islands

•As molten rock rises up between oceanic plates, the plates __________________

•Spread apart

•Most volcanoes and earthquakes mark the location of _________

•Plate boundaries

•A long chain of gently-erupting volcanic “mountains” on the ocean floor with a deep rift in the center is called a _____________________

•(mid-) ocean ridge

•What are the two major types of convergent boundaries?

•Subduction and collision

•How do volcanoes at mid-ocean ridges erupt?•Why?

•Gentle, oozing eruptions• b/c magma is silica-poor, which makes it thin & runny (gases escape easily)

•What are 3 features of oceanic-continental convergent plate boundaries?–1.–2.–3.

–1. trenches (near the coast)–2. volcanic mountains along the coast of the (overriding) continental plate–3. earthquakes

•__________________ commonly occur along transform plate boundaries.

•Earthquakes

•When two continental plates collide, what happens?

•Mountains form & continents can fuse

•_________________ is the theory that describes the formation, movements, and interactions of Earth’s lithospheric plates.

•Plate tectonics

•Why does one plate subduct below another?

•b/c the subducting plate is more dense

•The San Andreas Fault is an example of a __________________ plate boundary.

•transform

•________________ in the asthenosphere (mantle) cause hot magma to rise and cool magma to sink, allowing for plate movement.

•Convection currents

•The Himalaya Mountains formed at what type of boundary?

•Continental-continental convergent (collision) boundary

•Magnetic reversals are formed in a __________ image on opposite sides of the ridge

•mirror