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Week 31 - Continental Drift, Plate Tectonics and Mountain Building

Week 31 - Continental Drift, Plate Tectonics and Mountain Building

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Course: Science 7 LearnNet
Book: Week 31 - Continental Drift, Plate Tectonics and Mountain Building
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Date: Saturday, 16 February 2019, 3:21 PM

Exercise 3.1


Lesson 3.1: Continental Drift



ACTIVITY A: Walking on Egg Shells

Required Readings

Science in Action 7
pages 392 to 394
or

Science Focus 7

pages 383 to 385



Well ... not quite egg shells but a shell of sorts. Get yourself a hard-boiled egg; crack the shell on the outside. Very slowly, move the pieces of egg around on the surface of the egg.




In some places the egg white is exposed and in other places, where the pieces of shells bump together they buckle or overlap. This is somewhat similar to the surface of the Earth.




The surface of the Earth is like the cracked eggshell. The pieces (called plates) are slowly moving around. Where they spread apart, molten rock is exposed and where the plates collide they buckle or they overlap.




The shell of the Earth's shell (or crust) is broken into about 18 pieces. These pieces move around colliding into one another. When they collide parts of the crust is thrust upward (like the eggshell) and mountains are created. The movement of the Earth's crust also causes earthquakes and volcanoes.


ACTIVITY B: History of Continental Drift

Required Readings

Science in Action 7
pages 392 to 394
or

Science Focus 7

pages 383 to 385

Close your eyes and imagine that all the continents of Earth are attached together to form one landmass. What would a map look like? If you look carefully at a map, do you notice how well South America and Africa fit together? Alfred Wenger noticed. He studied the shape of the continents and then collected evidence from a variety of different sources and developed the Theory of Continental Drift.

Originally all the continents formed one super continent called "Pangaea." Follow this link to watch a video about Pangaea.

http://www.odsn.de/odsn/services/paleomap/animation.html

Look at the maps at this site to see how the map has changed gradually.

pubs.usgs.gov/publications/text/historical.html

 




PROOF OF PANGAEA

Read your textbook and then scroll down to read about evidence of Pangaea.


FOSSIL EVIDENCE



    The Fossil Record is Proof of Pangea

ROCK EVIDENCE




    Rock Evidence of Pangea

Almost all fossils are found in sedimentary rock. Sedimentary rock is formed when layers of sand gravel mud (soil) and plants are compressed into rock. Sedimentary rock forms layers or strata. These layers of rock are very distinctive for any given area. In order to understand Earth's history, we need to place geological events in their correct order. Geologists have discovered that the geological structures of the rocks in South West Africa and South East Brazil were distinctively identical, and the age of the rocks at these two areas was the same. This distinctive rock strata shared by the two land masses suggests that these two areas were once joined together.


Coal can be found underneath the cold and dry Antarctic ice cap and here in Alberta. We know that coal can only be formed in warm and wet conditions. This could mean that Antarctica and North America were once together with the other continents as part of Pangaea, and was once in a warm and humid region. Coal was formed before the continents drifted drifted apart. Antarctica became covered with ice and snow and the jungle ecosystem in Alberta transitioned to seasonal woods and grassland. That is why the coal can be found buried under areas that don't seem right for coal formation.


      ROCK STRATA


    COAL DISTRIBUTION
GLACIER EVIDENCE



    Evidence from Glaciation

      Glaciation in South America, Africa, India, and Australia is best explained if these continents were once connected. Glaciers covered all or part of each of these continents during the same time period in the geologic past.

    If the continents were in their present position, a major glaciation event that covered nearly all of the continents and extended north of the equator would be required. Geologists have found no evidence of glacial action in the northern hemisphere during this time period. In fact, during this time period, the climate in North America was warm.



    Wegener proposed that the continents were adjacent to each other during the glacial event. Therefore, glaciers spread over a much smaller area in the southern hemisphere and probably did not influence the climate of the northern hemisphere.

Exercise 3.1: Fossil Evidence




Exercise 3.2


Lesson 3.2: Plate Tectonics


INTRODUCTION
"Continental drift was first proposed by Alfred Lothar Wegener in 1912, he suggested that all of the continents were once joined together in one super continent, which he called Pangaea. He cited evidence of various types to support his theory, the similarity of the coastlines, fossil evidence, rock sequences and glacial evidence. Although his theory is now accepted world-wide by most geologists, at that time northern hemisphere scientists found it difficult to believe, as Wegener could not offer a sensible mechanism for continental drift to take place. In 1928 Scottish Geologist Arthur Holmes suggested a mechanism, convection in the Earth's interior. Wegener died before he could adapt the ideas of Holmes but with some modification these ideas now make a major contribution to Plate Tectonic Theory."

Text taken with permission from http://tiger.chm.bris.ac.uk/cm1/LesW/



ACTIVITY B: When Plates Collide

Required Readings

Science in Action 7
pages 395 to 400
or

Science Focus 7

pages 390 to 394


Go to these web sites and view the 4 basic types of interactions between plates.

www.pbs.org/wgbh/aso/tryit/tectonics/convergent.html

www.extremescience.com/PlateTectonicsmap.htm

http://www.learner.org/interactives/dynamicearth/slip2.html

 


ACTIVITY C: Modern Proof of Plate Tectonics


Required Readings

Science in Action 7
pages 395 to 401
or

Science Focus 7

pages 386 - 389

By plotting the locations of earthquakes and volcanoes, scientists noticed a very specific pattern.


Because plate motions are global in scale, they are best measured by satellite-based methods. The late 1970s witnessed the rapid growth of space geodesy, a term applied to space-based techniques for taking precise, repeated measurements of carefully chosen points on the Earth's surface separated by hundreds to thousands of kilometers.



The ship Glomar Challenger, was designed specifically for exploring the deep ocean floor. It collected rock samples from the bottom of the ocean floor. These rocks were analyzed and dated.

With technology, we now know which direction each plate is moving and approximately how fast.

Exercise 3.2: Proof of Plate Tectonics

 

Exercise 3.3


Lesson 3.3: Mountain Building


ACTIVITY A: Mountains


Required Readings

Science in Action 7
pages 402 to 408
or

Science Focus 7

pages 412 to 416

Mountains are built when the Earth's crust is deformed through heating and pressure. As you learned in earlier lessons, the Earth's plates are constantly moving. The pressure and heat caused by these movements cause rock to fold and fault, creating mountains.

When two sections of the Earth's lithosphere collide along subduction zones, the slabs pile into each other, causing one or both slabs to fold up like an accordion. This process elevates the crust, folds and deforms it heavily, and produces mountains. Mountain building and subduction usually go together. Mountains are usually found along the edge of plates where subduction is or has occurred.

Your textbook has an excellent section on "Mountain Building". Using your textbook, answer the questions below.

 

Exercise 3.3: Mountain Building

Section 3 Notes

You have two options for your Section 3 Quiz - a multiple choice quiz or a written response quiz. You may choose to write the multiple choice or the written response. You only need to write one of them, so the choice is up to you! You are allowed to try both quizzes if you want, but it is not required.

The quiz attempt with the highest grade will be the one that is recorded on your report card.

The multiple choice quiz has 10 multiple choice, matching, and true/false questions. You have 15 minutes to complete it. As soon as the quiz submitted it will be auto-graded and you will receive a grade immediately.

Click the image above to start your quiz

The written response quiz has 5 short answer questions. Your responses must give a complete and detailed answer to the question. You have 20 minutes to complete the quiz. This quiz needs to be manually marked by your teacher, so you may have to wait a few days to get feedback and a grade.

Click the image above to start your quiz