Name:
Date:
Block:
Recall: The Structure of the Earth
Plate Tectonics:

refers to the movements of plates (large segments of
continents and ocean) around the Earth’s surface.
 These land masses are seen as a giant
, and any one mass
can’t move without
between or
with other pieces
 They move on the Lithospheric plates on the Liquid Mantle and move along by
in the magma.
 Convection currents in the asthenosphere of the mantle.
 There are
minor plates –
major plates and
plates total.
of the plates – near the borders of plates where all
 It is on the
the action is! (earthquakes, volcanoes, mountain building!)
 These edges of the plates are called
 These tectonic plates move approximately
due to
!!!
 So in 100 million years, there will be 1250 miles of movement!!
The “Ring of Fire”!
 The ring of Fire is a Ring around the
(on the
edges of the Pacific tectonic plate) where there are numerous
and
.
 Why???
 There are
of the
Pacific plate there– so there is lots of jostling, smashing, and moving where all the
edges meet.
Plate Boundaries:
 At the edges of the plates is where all the action occurs because of all the
 When Plates move – there are only 3 choices they have…
1)
2)
3)
4)
3 types of Plate Boundaries ~ (Ways plates can move)
1. ______________________________ boundaries:
 Definition: 2 plates move away from each other opening a gap called a
___________________________
 Sometimes, _______________________ rises to the Earth’s surface in the trench and this
area is called a ____________________. (the Hawaiian islands were formed from hot spots!)
 As molten rock comes up through the gap created by the __________________________
plates, it pushes the old crust aside causing it to buckle.
 This process is called ___________________________
This is the symbol on a map of
diverging plates:
This is DIVERGENCE or Ridge push
Divergent Plates under Water (under the Oceans):
 When oceanic tectonic plates diverge (pull part) under water, the spreading center is called
___________________________________ or __________________________________.
 Because the magma rises up through the trench and pushes the old crust aside, new
__________________________ is created
 This process is called ____________________________________________
Eg. The Mid-Atlantic Ridge
Divergent plates under Land (under continents):
 When tectonic plates diverge, pull apart, under land, the spreading center is called a
___________________________________.
 This is ________________ common than spreading over water
 Eg. Diverging plates in Eastern Africa are slowly pulling the land apart.
2. _______________________________ Boundaries:
 Definition: When 2 plates move __________________________ each-other
 When they collide, they push on each other and one plate ___________________________
the other. The one that dives under is the more ____________________ (heavier) plate.
 The process of one plate diving under the other is called ____________________________
 Places where you find subduction are called ______________________________________
 When Subduction occurs – the edge of the plate _______________________ deep into the
mantle and starts to __________________ creating magma. That magma can make it’s way
up through cracks in the crust and form ____________________________.
 When the plate subducts, it “pulls” the rest of the plate with it - This is called
__________________ ( the whole slab(plate) is pulled under the other slab(plate))
 This slab pull helps keep the tectonic plates in motion.
This is Convergence
This is CONVERGENCE
This is DIVERGENCE

There are 3 Types Convergence:
OCEANIC –CONTINENTAL Plate Convergence:
 When a dense (___________________) oceanic plate collides with a less-dense
(_________________) continental plate, the __________________________ plate subducts.
 This creates a deep underwater valley called a ________________________.
 As the subducting plate moves deeper, it starts to melt and magma can work it’s way to the
surface forming ________________________ Volcanoes
 A chain of volcanoes = ____________________________________.
 This force of collision between the 2 plates creates mountain ranges as the continental rock
crumbles and folds

Symbol for convergence on maps
Oceanic – Continental Convergence

OCEANIC –OCEANIC Plate Convergence:

 _____________________________________ occurs when 2 oceanic plates converge/collide.
 The denser plate subducts under the other, a deep _________________________ is formed,
and the subducting plate sinks deep into the _________________
 This interaction may produce a long chain of volcanic islands known as a _______________ 
_________________________________ ( ie. Japan islands)

Oceanic – Oceanic Convergence

CONTINENTAL – CONTINENTAL Plate Convergence:
 When continental plates collide, subduction ____________________ occur because the plates
are the same density.
 Instead, the plates hit _________________ and their edges crumple and fold forming great
___________________________________ ranges ( ie. The Himalayas)
 The Himalayas are the highest and _______________________ mountain range and are
increasing in height several ________ a year due to continuous convergence of the plates!

Continental- Continental Convergence
Think you can summarize Divergence and Convergence? Try to label the following letters
with the appropriate term!
A.
B.
C.
D.
E.
F.
G.
3. _________________________________ Boundaries
 Definition: 2 plates slide past one another
 Because they are sliding horizontally past each other – no __________________________ or
_________________________________ are formed
 _________________________ (breaks in rock layers due to movement on either side) forms.
Eg. San Andreas Fault