Pangaea

Our Changing Earth

Source


CONTINENTAL DRIFT AND PLATE TECTONICS

So we begin with the story of the great continent of Pangea, and Alfred Wegener (1880-1930), a German meteorologist who said the continents were all one one big land mass as evidenced by how well they all fit together like puzzle pieces. He later backed this up with fossil evidence from opposite sides of the Atlantic Ocean, evidence of matching rock formations on either coast, as well as tropical fossils found in Antarctica, but his fellow scientists found it all quite unconvincing. Wegener was proposing the land mass was in motion and the continents had been torn apart by some force. Although most scientists agreed with the theory, he failed to produce the mechanism by which the continents could move. He said somehow they moved through the ocean, but no one accepted that continents could simply move across the ocean without being torn apart. Wegener devoted the rest of his life to trying to find more evidence but unfortunately, he froze to death in Greenland still searching. (Trefil, 2010) (USGS, 2011)

It wasn’t until after World War II that scientists would again take a look at the ocean floor and find some anomalies that might prove Wegener’s theory after all. When they mapped the ocean floors they thought they would find a flat surface with run off from the continents, but instead they found a dramatic landscape of mountains, valleys, and canyons. (Trefil, 2010)

sea floor spreading
sea floor spreading


In the 1960’s scientists began to study the ocean floor and its magnetism. There are magnetic parts to the rock when it is in its lava state and before it cools, it will align with the magnetic north pole, which the scientists also note, have changed throughout the life of the earth. (The reason is unknown) Through this study, and comparing stripes of magnetic rock on the bottom of the Atlantic and Pacific Ocean, scientists came up with the concept of sea floor spreading. Each time new lava makes its way to the surface, the magnetic parts align with the current magnetic north – at the same time the new rock is pushing the continents apart and over long periods of time, a striping pattern can be seen in the rock. This data was used to also tell the age of the ocean floor. Rocks near the fissures and the mid-Atlantic Ridge were quite young. Rocks closer to the East US coastlines were older. (Trefil, 2010)

Radio astronomy was used to confirm the finding of sea floor spreading and the fact that the continents are moving farther apart. The distance between North America and Europe grows by 5cm or 2 inches per year. The study of all of these sciences; the rock dating, paleomagnetism, ocean floor spreading, and other data is called plate tectonics. Scientists today accept this concept because of all of the data, and the mechanism by which the theories are proven. Wegener had only a theory and very little evidence to back it up. He, unfortunately, did not have the technology to prove his theory, which was only the tip of the iceberg, so to speak. (Trefil, 2010) (Sander, 2012)

sea floor spreading
sea floor spreading

The process of scientific method and theory development is a six step process: Observation, theory, prediction, tests, results, conclusions. The scientist starts with an observation. For purposes of explanation I’m going to be really simplistic. He puts a pot of water on the stove and lights the fire. He comes back in half an hour and the water is gone. That is the observation. The theory is not that that water magically disappeared, because this guy is a scientist. He thinks the water went somewhere. He thinks (theory) that applying heat to water causes it to turn into a gas and evaporate. (He’s not that smart really, his friend told him about it the other day but if his friend did it, he should be able to replicate the same experiment.) (Trefil, 2010)

He predicts that he can do the same thing, (add fire to the pot to make the water disappear) but “catch some of the water in action as vapor if he uses a lid. He tests this theory and puts the water on the stove in a pot with a lid and goes about his business. He hears a gurgling and comes back. He lifts the lid slowly and vapor is released. “Eureka!” he screams and dances around. The result is that yes, if he adds heat to the water, he can make water vapor. He concludes that water can be both a liquid and a gaseous vapor.


I told you it was simplistic. But that’s how tedious science can be. Every idea must be tested and retested so that someone else can repeat it under the same conditions then it is known as a scientific fact and follows a scientific law of something.

This method helps us understand our natural world. The world behaves according to certain established laws and rules. They’re not made up, but tried and tested facts like the law of gravity. On earth there is a specific law of gravity, a law of motion, and certain things that are always true. If something seems to defy a specific principle, there is an explanation (usually – or we just don’t know yet). There are a set of testable theories that make scientific laws verifiable. There are new discoveries all the time. How cool would it have been to have been around when electricity was discovered and harnessed?


In our natural world, it is hard yet not impossible to predict things like tsunamis and earthquakes because of the grand scale of the earth. There are signs and precursor events leading up to things like a volcano eruption…but can we predict the week, month, day, hour or a volcanic event? And if there wasn’t enough time for a full evacuation, how does one proceed? What if the prediction is wrong? The earth is still a mystery in many ways.

Plate tectonics provides the mechanism for continental drift because it explains how the earth’s surface is broken up into about twelve tectonic plates on top of the earth’s mantle. In between these plates are fissures or cracks that sometimes allow these plates to move. The science behind the movement of the plates can be explained through subduction and convergent plate boundaries. Through this process the earth is not getting larger, but rather is folding under and being recycled. (Trefil, 2010)

plate tectonics
plate tectonics


Subduction happens when there is new rock being formed from magma, and it forces one end of a crustal plate to be pushed below the edge of another. And with all of the plates moving together, no plate can shift without affecting another, even if it is thousands of miles away. While the Atlantic Ocean is getting wider and pushing the continents of Africa and South America away from each other; the Pacific Ocean plates are busy subducting . As two plates pull away from each other this is called divergent plate boundaries, as in the Atlantic Ocean where the continents are moving apart. In the Pacific Ocean, where the subduction is going on, the crust is pushed below the edge of other plates and recycled; these are called the convergent plate boundaries. (Giamportone & Booker, 2010)

The third kind of tectonic plate boundary is the transform –fault boundary. This occurs when two faults are sliding horizontally past each other. Most of these faults are in the ocean but the famous one on land is the San Andreas Fault which takes up roughly 2/3 the length of California. These two plates are constantly rubbing against each other. Land on the Pacific plate is moving in a North Westerly direction as opposed to the plate to the right (the North American plate). Earthquakes occur along fault lines such as these, on land or in the ocean. (Giamportone & Booker, 2010)

San Andreas Fault
San Andreas Fault
Pacific Ring of Fire
Pacific Ring of Fire


The earth is not getting any bigger. If the ocean floor is spreading on the Atlantic side and pushing the continents farther apart, that distance must be made up on the opposite ends somewhere. The area in the Pacific and Indian Oceans, however, is not spreading. It is known as The Ring of Fire. From Chile to Mexico to California to Alaska (Aleutian Islands) then Russia (Kamchtka Peninsula), Japan and Micronesia, then New Zealand. This is where all of the subduction activity is occurring. Rings of volcanoes (Over 75% of the world’s volcanoes are in this area.), lava flows, moving earth, fault lines, tsunamis; this is a place of motion. Here the sea floor is folding, crunching, and the tectonic plates are subducting under each other. (Giamportone & Booker, 2010) (Svitil, 2011)

The Himalayas are forming (still) by a different process, but still violent. (Funny how this violent process can be so beautiful) They are being formed by the continent riding on top of two converging plates; the land has collided and is being forced up sharply. Compared to the Smoky Mountains on our East Coast, they are very young. If it was ocean material riding on top of these converging plates the result would be a deep ocean trench. (Trefil, 2010)

This has been an in-depth look at plate tectonics and a simple overview of the scientific method of looking at things. The main thing to remember is that the Atlantic Ocean is getting larger, due to the process of sea floor spreading, and the Ocean has a feature of Mountain ridges and valleys and plateaus that has been mapped. The Pacific Ocean is much more dynamic in terms of seismic activity, volcanic activity and subduction.

From above, so silent...The process take millions of years...
From above, so silent...The process take millions of years...

REFERENCES

Giamportone , J., & Booker, W. (2010). Plate tectonics: Plate boundaries. Retrieved from http://www.platetectonics.com

Sander, L (February 1, 2012). Moving Plates. Live Chat #9

Svitil, K. (2011). Savage earth: Ring of fire. Retrieved from http://www.pbs.org/wnet/savageearth/hellscrust/html/sidebar3.html

Trefil & Hazen. (2010). The Sciences: An Integrated Approach. (6th ed.). Hoboken, NJ: Wiley & Sons Inc. www.wileyplus.com

USGS , (2011, September 19). Plate tectonics: Historical perspective. Retrieved from http://pubs.usgs.gov/publications/text/historical.html

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Comments 21 comments

drbj profile image

drbj 4 years ago from south Florida

Thank you, Erin, for this absolutely fascinating hub. You have greatly enriched my meager knowledge of Wegener and his Pangeatic theories. Made me want to do some research on my own, m'dear.


Erin LeFey profile image

Erin LeFey 4 years ago from Maryland Author

Hi Dr.

I learned a lot this term, questions I just never thought to ask. I've never been the really scientific type, but I enjoy the classes. I'm glad you enjoyed it too!


CMCastro profile image

CMCastro 4 years ago from Baltimore,MD USA

Hello,Erin, I am glad you have a wonderful informative hub about the changes in the planet. I even knew at a very young age that all the continents must have been connected together; my Mother even spoke about Atlantis, but I was never given the reading material explaining about the shift in the plates upon this earth. I will have to bookmark this hub, because there is a lot of info here that is awesome to study. I would like to also share it with the Prophet in my Church Ministry who is teaching us in Classes about the changes in the Universe and even in the government and economy and how to be prepared for the future of the planet.

I hope that you will be able to share more information that will help us in the future. It is good to see you on HubPages today.


Erin LeFey profile image

Erin LeFey 4 years ago from Maryland Author

Hi Christina,

Nice to see you again! Hope all is good for you! I'm glad you enjoyed my brief journey into the scientific world. At first I was thinking, what's a criminal justice major doing in a science class? Then I realized, it's just to make us more well-rounded and to teach us how to think logically. I'm glad you enjoyed the hub. I'd love to know what happened to Atlantis as well - or if it is just a myth. This class didn't address that.

Love ya, Erin


always exploring profile image

always exploring 4 years ago from Southern Illinois

Erin, I am amazed and impressed . This is a great educational hub. I learned some new data. I still wonder about Atlantis. I have been reading Edgar Cayce's predictions. He was a firm believer in the existence of Atlantis. Thank you for sharing my friend...


Ruby H Rose profile image

Ruby H Rose 4 years ago from Northwest Washington on an Island

I love all the learning I achieve by reading an outstanding Hub like this! Keep it up. Very interesting.


Erin LeFey profile image

Erin LeFey 4 years ago from Maryland Author

My sister! I'm learning big words in college! lol I was so intrigued with all of this, we actually learned that Atlantic Ocean is getting bigger and the Pacific getting smaller, we actually moving farther from Europe (inches) every year! I still wonder about Atlantis too, but with all the Earth's movement, why not?

Love ya, Erin


Erin LeFey profile image

Erin LeFey 4 years ago from Maryland Author

Hi RubyRose, Thanks so much for reading and I'm so glad you enjoyed it! Take care!


Denise Handlon profile image

Denise Handlon 4 years ago from North Carolina

This is an amazing hub, Erin! and, coincidentally, this is the third time in one week, in which I've come across the word in your title...all for very different reasons. Hmmmm, is someone trying to tell me to pay attention to this? Take care. Voted up.


b. Malin profile image

b. Malin 4 years ago

I am so intrigued by the knowledge that the Atlantic Ocean is getting Bigger... What a Fascinating Hub Erin, I Loved reading, and Learning through your Hub, and I know I would Enjoy this Science Class too. Keep up the good work of Reporting to us here on Hub Pages.


thougtforce profile image

thougtforce 4 years ago from Sweden

This is my favorite subject Erin and I never get tired of reading about it! Are you studying Earth Science now? Then I will congratulate you and I am also a bit envious because of the very interesting and fascinating subject. I could do it over again! You did a great article about tectonic and Pangea!

Voted up, interesting and more

Tina


JKenny profile image

JKenny 4 years ago from Birmingham, England

I've always had a fascination with plate tectonics and the movement of the continents. I really enjoyed reading your hub, you explained everything in a clear and thorough way. It reminded me of something I read on the internet about predicting the future of continental drift. They reckon in another 250 million years, all of the continents will be joined together again, I think they've called it 'Pangea Ultima' Voted up.


mckbirdbks profile image

mckbirdbks 4 years ago from Emerald Wells, Just off the crossroads,Texas

Hi Erin. What a great job you have done here. Your hub is packed with well presented information. School argees with you. Even your avatar looks happier!

Woe, almost forgot to vote.


Erin LeFey profile image

Erin LeFey 4 years ago from Maryland Author

Thanks so much Denise, everything happens for a reason! :)


Erin LeFey profile image

Erin LeFey 4 years ago from Maryland Author

Hi B.

so that means more ocean front property for us? I don't think so, I guess it just means more water. And that our friends across the pond are getting farther away from us, I think like a few inches a year!


Erin LeFey profile image

Erin LeFey 4 years ago from Maryland Author

Hi Tina, it was just one class in my degree program, I was in another class at the same time. Right now I'm in organizational management. They move so fast. I wish I had more time to write. I miss it!


Erin LeFey profile image

Erin LeFey 4 years ago from Maryland Author

Hi JKenny, Thanks and yes, we learned about that too, only the new group of continents was called "Amasia"?

All of them are grouped together again in the Pacific side = no time soon though. After learning about so much activity that is causing the fault lines and volcanoes and such, I don't think I could live in San Francisco. My brother does though.


Erin LeFey profile image

Erin LeFey 4 years ago from Maryland Author

Thanks! I love learning and I love school. I only don't like that I have to write so much that I only have time to write the reports for school, because there are so many. Thanks so much for the kind remark about my avatar, that was because the Ravens made it to the Playoffs! :) lol

I miss you all, I'm trying to sneak around when I have free time.


Docmo profile image

Docmo 4 years ago from UK

That was a laudably concise master-class on plate Tectonics, Erin. you have done a great job in succinctly summarising the theories and principles. Now I am suitably equipeed with the concepts of convergence, subduction and transformation. My first intro to plate tectonics was when I learnt as a child there was fossils of sea creatures on top of the Himalayas - this was explained to me that they were pushed up from the sea floor through seismic activity- powerful how those images can be. Thanks for sharing. Voted up/awesome.


Erin LeFey profile image

Erin LeFey 4 years ago from Maryland Author

Thanks so much for reading Docmo, glad to share it! I'm in a criminolgy class now, not much to share just learning laws...:)


IzzyM profile image

IzzyM 3 years ago from UK

You should be proud of this hub, because it explains so much in easy-to-understand terms. I am really annoyed because I wanted to link this hub to one of mine (on another subdomain) and yours, under the word Pangaea, and it was not listed in HP's link tool. I went and searched for it and it was not easy to find, but I did find it in the end. This is the classic example of a 'stellar hub' - this being the latest term - but HP wants them and doesn't promote them internally? What's that all about? Anyway, thanks, you now have another link, and this hub well deserves it :)

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