Week 31 - Continental Drift, Plate Tectonics and Mountain Building

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