CONTINENTAL DRIFT TO PLATE TECTONICS

Joshua K. IsbleINT Task 1

Changes in the Plate Tectonic Theory over time

“Plate Tectonic” theory began in 1915 and created by Alfred Wegener (Glasscoe, 1998) and originally called the Continental Drift Theory

Wegener believed that the continents were in constant motion drifting apart.

Wegener’s Evidence(USGS, 2012)

Continents looked like they could fit together like a jigsaw puzzle Idea of Pangaea(Photo: Pangaea Partners, 1998)

Similar Fossils were found on different continents separated by thousands of miles

Matching rock types on different continents separated by thousands of miles

Similar mountain structures on different continents

Why others didn’t believe Wegener’s Theory?

Wegener could not explain HOW the continents were

moving.

Continental Drift Theory QuestionedWegenor’s passion for the Continental Drift Theory led to what we believe today as the Plate Tectonic Theory. (USGS, 2012)

Plate TectonicsStudy of the lithosphere and belief that the earth is divided up into a number of crustal plates. These plates move or collide with each other. (Plate Tectonics, 2012) Continental plates move and create earthquakes, tsunamis, mountain ranges, etc.

1. The age and ruggedness of the ocean floor

2. The earth’s magnetic field3. Seafloor spreading and the

recycling of the ocean floor4. Earthquake and Volcanic Activity

Evidence to support Plate Tectonic Theory

Scientists discovered that the ocean floor was not flat and featureless as they thought originally, but that it contains many geological features including underwater mountain ranges. (USGS, 2012)

This supported the idea of the Plate Tectonic Theory.

Ocean Floor Mapping

(USGS, 2012)

Magnetic Striping and Polar Reversals

Magnetic striping and polar reversals contributed to the belief of the Plate Tectonic Theory. A pattern was discovered on the ocean floor. It was found that the magnetic fields drift a small portion each year. It was proven that the Earth’s magnetic field is continually evolving. (USGS, 2012)

Three pieces of evidence support the theory of seafloor spreading which adds more evidence to the Plate Tectonic theory. (USGS, 2012)1. From the ridge and moving outward,

the age of the crust gets older2. Younger rocks have normal polarity3. Each strip has alternating magnetic

polarity

Seafloor spreading and ocean crust recycling

(2004 Indian Ocean Earthquake, 2012)

Earthquake and Volcanic Ocean Activity

Supports the idea of seafloor spreading which causes the movement of the crustal plates and validated Wegener’s Continental Drift Theory (USGS, 2012)

(USGS, 2012)

THE IMPACT OF THEEXXON VALDEZ OIL SPILL

Exxon Valdez Oil Spill of 1989(Oceana, 2012)

In 1989, over 11 million gallons of North Slope crude oil spilled into the waters of Prince William Sound off the coast of Alaska.

250,000 seabirds, 144 bald eagles, 4,400 sea otters, and 20 whales were among the first animal life to be affected.

Billions of salmon and herring eggs were also damaged or destroyed.

The spill covered over 1300 miles of coastline.

Commercial fishing opportunities were depleted which effected many villages in Alaska causing great economic hardship on the people.The uncertainty of the event caused many people to suffer psychologically and economically.The local government took a hit because funds were depleted for cleanup.Local businesses lost employees because the oil cleanup jobs were higher pay.

Social and Economic Impact (Gill, 2011)

Changes made since the spill: Oil Pollution Act of 1990 was passed restricting any vessel that has spilled over 1 million gallons in the Prince William Sound.

Alaskan regulations increased mandating two tug boats escort every load. That has changed to one Escort Regulation Vehicle.

US Coast Guard monitors tankers via satellite. Improved production ability of skimming systems to remove oil – 10% ability improvement since 1989

Barrels are available to hold the oil clean up Clean up chemicals are now stockpiled in case of another oil spill. (Cleveland, 2010)

• Clean up can be even more devastating than the actual oil spill. (Cleveland, 2010) There was no documentation of this prior to the oil spill at Valdez.

• Oil spills effect the sea life longer than originally thought.

• Rocky rubble shore need to be a priority to protect because oil tends to saturate those areas. (Cleveland, 2010)

• Long term effects even on fish eggs with defects and lack of growth.

• Gave scientist a way to learn from tragedy and ecological disaster.

• Allowed scientist to learn how oil spills effect the environment, implementation of clean up, and how to recover in future events.

What we have learned:

ReferencesCleveland, Cutler (Lead Author);NOAA (Content Source);Peter Saundry (Topic Editor)

"Exxon Valdez oil spill". In: Encyclopedia of Earth. Eds. Cutler J. Cleveland (Washington, D.C.: Environmental Information Coalition, National Council for Science and the Environment). [First published in the Encyclopedia of Earth June 9, 2010; Last revised Date December 20, 2010; Retrieved October 26, 2012 <http://www.eoearth.org/article/Exxon_Valdez_oil_spill?topic=58075>

Gill, Duane; Picou, Steven; and Liesal Ritchie. (2011) The Exxon Valdez and BP Oil Spills: A comparison of initial social and psychological impacts. American Behavioral Scientist, (XX)X 1-21. doi:10.117710002764211408585 or http://abs.sagepub.com

Glasscoe, Maggie. (1998) The Southern California Integrated GPS Network. History of Plate Tectonics. Retrieved on October 25, 2012 from http://scign.jpl.nasa.gov/learn/plate2.htm

McNally, Ronald. (n.d.) The Pacific Ocean Floor. Retrieved on October 26, 2012 from http://www.spiralupdatenews.com/pacificoceanfloormap.html

Oceana (2012) Exxon Valdez Oil Spill Facts. Retrieved on October 26, 2012 from http://oceana.org/en/our-work/stop-ocean-pollution/oil-pollution/learn-act/exxon-valdez-oil-spill-facts

Pangaea Partners. (1989) Retrieved on 10/26/12 from http://www.pangaeapartners.com/Plate Tectonics. (2012) In Dictionary.com. Retrieved on October 26, 2012 from

http://dictionary.reference.com/browse/plate+tectonicsU.S. Department of the Interior, U.S. Geological Survey (2012) Retrieved on October 26,

2012 from http://pubs.usgs.gov/gip/dynamic/dynamic.html 2004 Indian Ocean Earthquake. (2012) In Wikipedia. Retrieved on October 26, 2012 from

http://en.wikipedia.org/wiki/2004_Indian_Ocean_earthquake