Name:________________________________ Date: _____________ Period:_______
Convection in the Mantle & The Theory of Plate Tectonics
Keyterms
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Density-mass/__________________ The amount of ________________ in a given area or volume
of that matter.
Fluid-matter that can __________________. Can be solids, liquids, or ___________________
Convection-__________________ _______________________ within a fluid.
Convection current -a _______________ that develops from a fluid moving from an area of
____________ density to an area of ____________ density.
How do convection currents form?
What are examples of convection currents?
Theory of Plate Tectonics
What is the theory of plate tectonics?
The ________________________________________________ explains the formation and movement of
Earth’s plates.
The lithosphere is broken into sections called ________________.
Plate Boundaries:
____________________ Boundaries- The place where two plates (pieces of the lithosphere) move apart.
Most divergent boundaries occur along a _________________________________ where sea-floor
spreading occurs.
What is a mid-ocean ridge?
It is an ___________________ mountain _________________ where new ocean floor is produced at a
divergent boundary.
Convergent Boundaries:
The place where two plates come ___________________________ (often called a collision).
When two plates collide, the ___________________ of the plate determines which one comes out on top.
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2 _________________________ plates collide= formation of ____________________________
1 ___________________ + 1 continental collide= oceanic sinks beneath the continental plate
(_________________________) and forms a ___________________ (a narrow, deep valley along
the ocean floor).
_________________________- the process by which oceanic crust sinks beneath a less dense plate.
Subduction Diagram
Transform Boundaries:
A place where two plates ___________ past each other, moving in opposite directions.
___________________________ often occur along transform boundaries, but ______________ is neither
created nor destroyed.
Diagram of plate movement:
Divergent
Convergent
Transform
Evidence for Plate Tectonics
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__________________________- The name of the single landmasss that broke apart 200 million
years ago and gave shape to today’s continents.
o Evidence for a Supercontinent
 Land features: mountain __________________ and _______________ fields
appear to line up according to the shape of continents.
 _________________: from ancient animals appear to link continents together as
well- mesosaurus, lystrosaurus (freshwater reptiles), glossopteris (plant).
 Climate: ___________________________ changes at specific locations show that
continents may have shifted toward or away from the equator over time.
Sea-Floor Spreading- the process by which molten __________________ adds new oceanic crust
to the ocean floor.
o The sea floor __________________________ apart along both sides of a mid-ocean ridge
(__________________________ boundary), as new crust is added.
Sea-Floor Spreading Diagram
How do we know the sea-floor actually spreads?
Evidence from _________________ material- new material is erupting along _______________________
ridges.
Evidence from ______________________ samples- the age of rocks has been identified through drilling
samples. Rocks __________________ from the ridge were the oldest, the youngest rocks were always in
the ______________________ of the ridges.