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.

Know and be able to locate all plates in red- 7 major and 2 minor 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 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) 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) Japanese Islands Indonesian 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)

Hotspot volcanism: http://tinyurl.com/y6dyd6 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: 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.