The Theory of plate tectonics,

Plate Movement, & Hot Spots

Do NowLandscapes 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

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)

Andes Mts

Cascade Mts

Subduction leading to collision (convergence) and formation of Himalayas

Subduction (o-c convergence)

Subduction followed by Collision

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

http://www.columbia.edu/~vjd1/subd_zone_basic.htm

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.

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’tEarth 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

• 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)

Mantle Plumes (Hotspots)

Which mountainIs 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. Name and describe the three types of plate boundary movement. Be able

to provide examples.2. Describe frictional coupling as it applies to plate movement.3. What is a mantle plume? 4. What are the primary melt mechanisms in the mantle?5. What topographic features result from plate movement and hot spot

activity? Be specific- demonstrate your knowledge.6. What natural disasters result from plate movement and hot spot activity?

Be specific- demonstrate your knowledge.7. Compare and contrast earthquake activity from divergence vs.

subduction.8. Compare and contrast volcanism from subduction vs. hot spots.