introduction to continental drift and plate tectonics (united streaming video) continents adrift: an...

Introduction to Continental Drift and Plate Tectonics

(United Streaming Video)Continents Adrift: An Introduction to Continental Drift and Plate Tectonics. Rainbow Educational Media(1995). Retrieved April 23, 2008, fromunitedstreaming: http://streaming.discoveryeducation.com/

Alfred Wegener stated that the continents move, and over time have come together and moved apart again

(2008). The Earth. Retrieved April 29, 2008, from Enchanted Learning Web site: http://www.enchantedlearning.com/subjects/astronomy/planets/earth/Continents.shtml

Evidence for Continental Drift

1. Similarities in the coastlines of the continents

Pompa, Plate Tectonics Mini Lecture. Retrieved April 29, 2008, from Gateway School District Web site: http://www.gasd.k12.pa.us/~dpompa/Mini%20Lecture.html

2. Identical fossil remains found in different continents



3. Age and type of rocks in different continents match up



4. Evidence of changes in climatic patterns



5. Seafloor spreading


(2004, October 4). Geology . Retrieved April 29, 2008, from National Park Service Web site: http://www.nature.nps.gov/geology/usgsnps/animate/A48.gif

Lithospheric Plates

• The earth's surface is made of two types of crust

• Thinner, denser oceanic crust, made from mafic lava

• Thicker, less dense continental crust, made from felsic lava

• These two types of crust make up the earth's lithospheric plates

(2008, January 25). Earthquakes Hazards Program. Retrieved April 30, 2008, from USGS Web site: http://earthquake.usgs.gov/learning/glossary.php?termID=57

Presently, 15 major lithospheric plates and 39 minor lithospheric plates exist. There are 12 others that have been identified, but no longer exist.

Major plates Minor plates Ancient Plates

African Plate Aegean Sea Plate Mariana Plate Baltic Plate

Antarctic Plate Altiplano Plate Molucca Sea Plate Bellingshausen Plate

Arabian Plate Amurian Plate New Hebrides Plate Charcot Plate

Australian Plate Anatolian Plate Niuafo'ou Plate Cimmerian Plate

Caribbean Plate Balmoral Reef Plate North Andes Plate Farallon Plate

Cocos Plate Banda Sea Plate North Bismarck Plate Insular Plate

Eurasian Plate Bird's Head Plate Okhotsk Plate Intermontane Plate

Indian Plate Burma Plate Okinawa Plate Izanagi Plate

Juan de Fuca Plate Caroline Plate Panama Plate Kula Plate

Nazca Plate Conway Reef Plate Rivera Plate Lhasa Plate

North American Plate Easter Plate Sandwich Plate Moa Plate

Pacific Plate Futuna Plate Shetland Plate Phoenix Plate

Philippine Plate Galapagos Plate Solomon Sea Plate

Scotia Plate Hellenic Plate Somali Plate

South American Plate Iranian Plate South Bismarck Plate

Juan Fernandez Plate Sunda Plate

Kermadec Plate Timor Plate

Manus Plate Tonga Plate

Maoke Plate Woodlark Plate

Lithospheric Plates

3 types of plate boundaries:


Lithospheric Plate Boundaries

Divergent BoundariesTwo plates moving apart

Example: along the Mid-Atlantic ridge

(2005). Plate Boundaries. Retrieved April 29, 2008, from Plate Tectonics Web site: http://www.platetectonics.com/book/page_5.asp


Convergent BoundariesTwo plates moving toward each other

Example: Himalaya mountains

(2005). Mountain Ranges. Retrieved April 29, 2008, from Plate Tectonics Web site: http://www.platetectonics.com/book/page_5.asp

Watson, J. M. (1999, May 5). Understanding plate motions. Retrieved April 29, 2008, from USGS Web site: http://pubs.usgs.gov/gip/dynamic/understanding.html#anchor15039288


Transform Fault BoundariesTwo plates grinding past each other

Example: San Andreas Fault, CA

Watson, J. M. (1999, May 5). Understanding plate motions. Retrieved April 29, 2008, from USGS Web site: http://pubs.usgs.gov/gip/dynamic/San_Andreas.html

(2006, May 26). Western Earth Surface Processes Team. Retrieved April 29, 2008, from USGS Web site: http://geomaps.wr.usgs.gov/socal/geology/inland_empire/socal_faults.html


Seafloor Spreading• Diverging tectonic plates

• Oceanic and oceanic crust moving apart• Results in a mid-ocean ridge

− “New” crust is created at these boundaries

(2007). Mid-Ocean Ridges. Retrieved April 25, 2008, from Water Encyclopedia Web site: http://www.waterencyclopedia.com/Mi-Oc/Mid-Ocean-Ridges.html

A topography (relief) map showing the world’s mid-ocean ridge system


Convergent Plate Boundaries

Oceanic-oceanic plate convergence =

Island Arc Formation

Old crust is “destroyed” at these boundaries as one plate slides under the other

All photos from: (2005). Plate Boundaries. Retrieved April 23, 2008, from Plate Tectonics Web site: http://www.platetectonics.com/book/page_5.asp

Oceanic-continental plate convergence = Volcano Formation (also known as a volcanic arc)

Old crust is “destroyed” at these boundaries as the denser oceanic crust slides under the lighter continental crust



Continental-continental plate convergence = Mountain Formation

Since both plates are of equal density, they crash into each other and bend and fold upward



Subduction zoneOccurs at convergent plate boundaries

Thinner, denser oceanic crust sliding under oceanic or continental crust

Results in an ocean trench


(2003, April 4). The Mariana Trench. Retrieved April 30, 2008, from The Mariana Trench Web site: http://www.marianatrench.com/mariana_trench-oceanography.htm

The Ocean Trench. Retrieved April 30, 2008, from Think Quest Web site: http://library.thinkquest.org/22752/Sea%20Structure/Trench.html

Subduction zoneConverging tectonic plates

Oceanic crust sliding under continental crust Results in volcanoes/volcanic arc

Huber, N. K. (1987). The Geologic Story of Yosemite National Park . Retrieved April 30, 2008, from Yosemite Web site: http://www.yosemite.ca.us/library/geologic_story_of_yosemite/genesis.html

Causes of Plate Motion

• Convection within the mantle•Said to be the driving force behind plate tectonics•Hot material rises, moves away from the heat source, cools and sinks

Predicted plate movement for the future

Listed on the table to the right are the speeds of some of the earth’s lithospheric plates, relative to the North American Plate (as if the N. Am. Plate were still). These speeds were calculated using the Plate Motion Calculator

Plate Relative movement

(cm/yr)

African 2.3

Antarctic 2.9

Arabian 6.2

Australian 8.8

Caribbean 1.1

Cocos 10.0

Eurasian 2.4

Indian 6.4

Nazca 3.7

North American 0.0

Pacific 1.4

South American 0.8

Juan de Fuca 5.4

Philippine 9.4

Present and future lithospheric plate motion

introduction to continental drift and plate tectonics (united streaming video) continents adrift: an...

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