Transcript plate boundary.

The Theory of
plate tectonics,
Plate Movement, &
Hot Spots
Do Now
Landscapes are constantly changing and Islands
are constantly being newly formed.
 Why is this happening?
 How do you think this occurs in nature?
Heat Transfer & Melting the Mantle
Convection  Plate Movement
Intraplate  Hot Spots
The Plate Tectonic Theory &
Location of the Plates
Theory of Plate Tectonics
• The theory that states that
Earth’s lithosphere and crust
are divided into plates, most of
which are in constant motion.
• The plates glide across the
underlying asthenosphere due
to frictional coupling caused
by convection heat transfer.
• Continents are located on
tectonic plates and move
around with them.
Tectonic Plates
7 Major (Larger) Plates
• North American
• South American
• Eurasian
• Indo-Australian
• Antarctic
• African
• Pacific
Minor (Smaller) Plates
• Nazca
• Philippean
• Cacos
• Arabian
• Juan de Fuca
• Caribbean
• Scotia
Know and be able to locate all plates in red- 7 major and 2 minor
How were Plate Boundaries Identified?
Scientist plotted the occurrences of earthquakes and
volcanic eruptions around the world
Earthquakes Worldwide
Tectonic Plates
HES
APES
Earthquakes and Plates
The map below shows the type of data that helped geologists understand where and why most earthquakes occur. Study the globa l distribution and
depth of earthquakes (M > 4) that occurred between 1975 and 1999.
Based on the locations of quakes, try to outline the edges of the lithospheric plates and label each with its name.
Large plates: No. American, So. American, Eurasian, Indo-Australian, Antarctic, African, Pacific
Smaller plates: Nazca, Philippine, Cocos, Arabian, Juan de Fuca, Caribbean, Scotia
Earth’s Lithospheric Plates
http://geomaps.wr.usgs.gov
Plate Movement and Melting
the Mantle via Convection
Plate Boundaries
and Movement
• The area where two plates meet is
called a plate boundary.
• 90% of geologic activity at the
surface of the Earth takes place at
the boundaries between tectonic
plates.
• Three main types of plate
boundaries:
 Convergent
 Divergent
 Transform
Convergence- 3 Types
Continental + Continental Convergence
(Collision)
Himalayan Mts
Continental + Oceanic Crust
(Subduction)
Cascade Mts
Andes Mts
Subduction followed
by Collision 
Himalayas
Subduction (o-c convergence)
Subduction leading to collision (convergence) and formation of Himalayas
Animation of Himalayas Formation: http://tinyurl.com/c5qvf2u
70 my in 2 min -The Himalayas Forming: http://www.youtube.com/watch?v=HuSHOQ6gv5Y
Oceanic + Oceanic Crust
(Subduction)
Indonesian Islands
Japanese
Islands
NOTE to reiterate the
formation of magma
via subduction:
The subduction slab
dehydrates and
releases that water to
the mantle, lowering
the mantle melting
temperature.
http://www.columbia.edu/~vjd1/subd_zone_basic.htm
Divergence
(Decompression)
•
•
•
•
•
Separation of 2 plates
“Seafloor spreading”
Mid-Ocean Ridges (MOR)
Forms new ocean crust
Mid-Atlantic Ridge which is
visible on land in Iceland
• Continental rifts (East Africa)
Mid-Ocean Ridge System
Think…..
If divergent plates allow magma to surface
creating new ocean floor, then why isn’t
Earth getting larger?
Transform Boundaries
•
•
•
•
Occurs at divergent boundaries
2 plates slide past each other
This sliding is not smooth. Plates lock
and build up tension.
Then the plates “snap” and release that
energy  earthquake!
http://www.youtube.com/watch?NR=1&v=ZxPTLmg0ZCw&feature=endscreen
Animation of transform, divergent, and subduction boundaries: http://tinyurl.com/pbxdt
Intraplate Melting of the
Mantle via Hot Spots
Mantle Plumes (Hotspots)
•
•
•
•
•
Individual column of magma that rises
up and punches through the
lithosphere
Forms chains of volcanoes as a plate
moves over the hot spot
~100 Hot Spots
10% of heat transfer
Decompression melting (like
divergence)
Which mountain
Is oldest?
Hotspot volcanism: http://tinyurl.com/y6dyd6
THINK!
• The expression of tectonic plate and hot spot activity at the surface
includes the formation of what features and results in what natural
disasters?
• All tectonic plate and hot spot activity results in Earthquakes.
– What is an earthquake?
– Where would you expect to have deep vs. shallow earthquakes? Explain.
• Volcanism occurs where you have melt mechanisms at play.
–
–
–
–
What is a volcano?
What are the 2 melt mechanisms?
Do they form new continental or oceanic crust?
Do you think the intensity of the volcanic eruption is similar for each melt
mechanism?
Diagram plate movement and hot spot activity on
the “Earths Interior” worksheet
Practice Worksheet
Self-Check:
Do you KNOW about plate movement and hot spot
activity?
You should be able to address the following:
1.
2.
3.
4.
5.
6.
7.
8.
Name and describe the three types of plate boundary movement. Be able
to provide examples.
Describe frictional coupling as it applies to plate movement.
What is a mantle plume?
What are the primary melt mechanisms in the mantle?
What topographic features result from plate movement and hot spot
activity? Be specific- demonstrate your knowledge.
What natural disasters result from plate movement and hot spot activity?
Be specific- demonstrate your knowledge.
Compare and contrast earthquake activity from divergence vs. subduction.
Compare and contrast volcanism from subduction vs. hot spots.