How the theory of Continental Drift

became the theory of Plate Tectonics

How the theory of Continental Drift

became the theory of Plate Tectonics

Evidence for Continental Drift

Evidence for Continental Drift

Fossil Evidence Glacier & Climate Evidence Continental Fit Structural & Strata Evidence

Fossil Evidence Glacier & Climate Evidence Continental Fit Structural & Strata Evidence

Continental DriftContinental Drift The evidence

suggested that the continents were once all together in a super-continent called Pangea

And that the continents were not always located in the same place on the globe.

The evidence suggested that the continents were once all together in a super-continent called Pangea

And that the continents were not always located in the same place on the globe.

http://www.knowledgerush.com/kr/encyclopedia/Pangea_supercontinent/

Drifting ContinentsDrifting Continents Alfred Wegener and

his supporters thought the continents were moving about the oceans like big rafts but couldn’t explain how this happened.

Alfred Wegener and his supporters thought the continents were moving about the oceans like big rafts but couldn’t explain how this happened.

http://tea.armadaproject.org/deaton/12.6.2004.html

New InformationNew Information

After Alfred Wegener died in 1930, Continental Drift Theory was mostly disregarded. . .

No one knew that the key information explaining how the continents to move would lie in a remote and vast part of the world that was still almost entirely unexplored.

After Alfred Wegener died in 1930, Continental Drift Theory was mostly disregarded. . .

No one knew that the key information explaining how the continents to move would lie in a remote and vast part of the world that was still almost entirely unexplored.

Secrets in the OceanSecrets in the Ocean

www.tripadvisor.com/LocationPhotos-g255055-Au...

Secrets in the OceanTopography

Secrets in the OceanTopography

Most people thought the ocean floor was a flat plain except for one set of mountains.Laying the trans-Atlantic telegraph

cable in the late 1850’s revealed there was some kind of high ridge in the mid-Atlantic

During World War II seafloor topography was mapped with sonar.

Most people thought the ocean floor was a flat plain except for one set of mountains.Laying the trans-Atlantic telegraph

cable in the late 1850’s revealed there was some kind of high ridge in the mid-Atlantic

During World War II seafloor topography was mapped with sonar.

Seafloor MapSeafloor Map

http://www.pacificislandtravel.com/nature_gallery/platetectonics.html

Secrets in the OceanMagnetism

Secrets in the OceanMagnetism

Magnetism in RocksWhen lava cools, minerals get “frozen” in

what ever position they were last in.The Earths magnetic field affects some

minerals so that they line up parallel to it.

Magnetism in RocksWhen lava cools, minerals get “frozen” in

what ever position they were last in.The Earths magnetic field affects some

minerals so that they line up parallel to it.

http://www.tulane.edu/~sanelson/geol111/pltect.htm

Measuring MagnetismMeasuring Magnetism

Magnetometers were used for minesweepers in World War II.

By the 1950’s scientists used magnetometers to study continental and ocean rocks to study paleomagnetism.

Magnetometers were used for minesweepers in World War II.

By the 1950’s scientists used magnetometers to study continental and ocean rocks to study paleomagnetism.

http://ofgs.ori.u-tokyo.ac.jp/okino/okino-res-e.html

Magnetic Polarity Time Scale

Magnetic Polarity Time Scale

Paleomagnetic studies showed that the Earth’s magnetic field had switched many times through geologic history

Paleomagnetic studies showed that the Earth’s magnetic field had switched many times through geologic history

http://roma2.rm.ingv.it/en/themes/17/magnetostratigraphy

Magnetic Stripes on the Ocean Floor

Magnetic Stripes on the Ocean Floor

http://pubs.usgs.gov/gip/dynamic/magnetic.html

Secrets in the OceanStructure of the ocean

floor

Secrets in the OceanStructure of the ocean

floor

Seismic studies tested the structure of the ocean crust.

Seismic studies tested the structure of the ocean crust.

http://www.rigzone.com/training/insight.asp?i_id=303

Secrets in the OceanStructure of the ocean

floor

Secrets in the OceanStructure of the ocean

floor These studies

revealed that about 100 km below the hard surface, the Earth got softer.

These studies revealed that about 100 km below the hard surface, the Earth got softer.

http://www.physicalgeography.net/fundamentals/10h.html

Secrets in the OceanEarthquakes

Secrets in the OceanEarthquakes

Scientists found that earthquakes in the ocean were centered at the seafloor ridges.

Scientists found that earthquakes in the ocean were centered at the seafloor ridges.

http://beyondpenguins.nsdl.org/issue/column.php?date=December2008&departmentid=professional&columnid=professional!science

Secrets in the OceanHeat

Secrets in the OceanHeat

The flow of heat through the ocean floor was discovered to be strongest/hottest at the ridges

The flow of heat through the ocean floor was discovered to be strongest/hottest at the ridges

http://eqseis.geosc.psu.edu/~cammon/HTML/Classes/IntroQuakes/Notes/plate_tect01.html

So what?So what?

None of the scientists who discovered these things thought they had anything to do with the theory of Continental Drift.

None of the scientists who discovered these things thought they had anything to do with the theory of Continental Drift.

So What?So What? Separately Harry Hess and Robert S.

Dietz saw some of this information and had the interesting idea which they called Sea Floor Spreading.

Separately Harry Hess and Robert S. Dietz saw some of this information and had the interesting idea which they called Sea Floor Spreading.

Harry Hess Robert S. Dietz

http://oceanexplorer.noaa.gov/history/electronic/1946_1970/media/dietz.html

http://www.amnh.org/education/resources/rfl/web/essaybooks/earth/p_hess.html

Sea Floor SpreadingSea Floor Spreading

Sea Floor Spreading was the key to the new theory of Plate Tectonics.

Alfred Wegener’s evidence, when put together with sea floor spreading went a long way to convince people that the continents, not only could but did move apart from each other—not as huge rafts, but as passengers on tectonic plates.

Sea Floor Spreading was the key to the new theory of Plate Tectonics.

Alfred Wegener’s evidence, when put together with sea floor spreading went a long way to convince people that the continents, not only could but did move apart from each other—not as huge rafts, but as passengers on tectonic plates.

Morley-Vine-Matthews Hypothesis 1966

Morley-Vine-Matthews Hypothesis 1966

Fred Vine and Drummond Matthews pulled it all together in publications in 1966

Morely’s article was rejected--looking back some say that it was the most significant piece of scientific writing ever rejected from a journal.

Fred Vine and Drummond Matthews pulled it all together in publications in 1966

Morely’s article was rejected--looking back some say that it was the most significant piece of scientific writing ever rejected from a journal.

Lawrence Morely Fred Vine, Drummond Matthews and Dan McKenzie

A new theory is bornA new theory is born By 1967 Sea Floor spreading was finally

accepted by most geologists and the theory of Plate Tectonics was born.

By 1967 Sea Floor spreading was finally accepted by most geologists and the theory of Plate Tectonics was born.

http://spot.pcc.edu/~aodman/GS%20107%20web/earth,venus,mars/earthmarsvenusindex.htm