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
Evidence for Continental Drift
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
3. Age and type of rocks in different continents match up
Evidence for Continental Drift
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
4. Evidence of changes in climatic patterns
Evidence for Continental Drift
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
5. Seafloor spreading
Evidence for Continental Drift
(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:
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
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
Lithospheric Plate Boundaries
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
Lithospheric Plate Boundaries
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
Lithospheric Plate Boundaries
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
Lithospheric Plate Boundaries
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
All photos from: (2005). Plate Boundaries. Retrieved April 23, 2008, from Plate Tectonics Web site: http://www.platetectonics.com/book/page_5.asp
Convergent Plate Boundaries
Continental-continental plate convergence = Mountain Formation
Since both plates are of equal density, they crash into each other and bend and fold upward
All photos from: (2005). Plate Boundaries. Retrieved April 23, 2008, from Plate Tectonics Web site: http://www.platetectonics.com/book/page_5.asp
Convergent Plate Boundaries
Subduction zoneOccurs at convergent plate boundaries
Thinner, denser oceanic crust sliding under oceanic or continental crust
Results in an ocean trench
Convergent Plate Boundaries
(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