![Page 1: Geology Plate Tectonics: A Scientific Theory Unfolds from Continental Drift](https://reader036.vdocuments.site/reader036/viewer/2022062423/5697bf871a28abf838c8890b/html5/thumbnails/1.jpg)
Geology
Plate Tectonics: A Scientific Theory Unfolds from Continental Drift
![Page 2: Geology Plate Tectonics: A Scientific Theory Unfolds from Continental Drift](https://reader036.vdocuments.site/reader036/viewer/2022062423/5697bf871a28abf838c8890b/html5/thumbnails/2.jpg)
Objectives
Review the historical background leading to the Theory of Plate Tectonics
Discuss the Continental Drift hypothesis
Review evidence supporting the Continental Drift hypothesis
![Page 3: Geology Plate Tectonics: A Scientific Theory Unfolds from Continental Drift](https://reader036.vdocuments.site/reader036/viewer/2022062423/5697bf871a28abf838c8890b/html5/thumbnails/3.jpg)
![Page 4: Geology Plate Tectonics: A Scientific Theory Unfolds from Continental Drift](https://reader036.vdocuments.site/reader036/viewer/2022062423/5697bf871a28abf838c8890b/html5/thumbnails/4.jpg)
Historical Background
• Catastrophism• Ortelius• Hutton• Pellegrini• Suess• Wegener
![Page 5: Geology Plate Tectonics: A Scientific Theory Unfolds from Continental Drift](https://reader036.vdocuments.site/reader036/viewer/2022062423/5697bf871a28abf838c8890b/html5/thumbnails/5.jpg)
Catastrophism
• Until the 1700’s most Europeans thought that a biblical flood played a role in shaping the earth’s surface.
• Geology was based on the belief that all changes were sudden and caused by a series of catastrophes
![Page 6: Geology Plate Tectonics: A Scientific Theory Unfolds from Continental Drift](https://reader036.vdocuments.site/reader036/viewer/2022062423/5697bf871a28abf838c8890b/html5/thumbnails/6.jpg)
Abraham Ortelius
• Dutch map maker, 1596
• Suggested that the Americas were “torn away from Europe and Africa by great floods and earthquakes”
• 1st time suggested in written form
![Page 7: Geology Plate Tectonics: A Scientific Theory Unfolds from Continental Drift](https://reader036.vdocuments.site/reader036/viewer/2022062423/5697bf871a28abf838c8890b/html5/thumbnails/7.jpg)
James Hutton
• Father of modern Geology, 1785
• Doctrine of uniformitarianism• The present is the key to the past• Geologic forces and processes - both gradual and
catastrophic
![Page 8: Geology Plate Tectonics: A Scientific Theory Unfolds from Continental Drift](https://reader036.vdocuments.site/reader036/viewer/2022062423/5697bf871a28abf838c8890b/html5/thumbnails/8.jpg)
Antonio Snider-Pellegrini
• Geographer, 1858
• Made two maps• Before (avant la separation)• After (apats la separation)
![Page 9: Geology Plate Tectonics: A Scientific Theory Unfolds from Continental Drift](https://reader036.vdocuments.site/reader036/viewer/2022062423/5697bf871a28abf838c8890b/html5/thumbnails/9.jpg)
Eduard Suess• Viennese Geologist, 1880
• Recognized an Atlantic type of margin• Identified by abrupt truncation of former
mountain belts
• Recognized a Pacific type of margin • Identified by parallel mountain ranges • Lines of volcanic areas • Frequent earthquakes
![Page 10: Geology Plate Tectonics: A Scientific Theory Unfolds from Continental Drift](https://reader036.vdocuments.site/reader036/viewer/2022062423/5697bf871a28abf838c8890b/html5/thumbnails/10.jpg)
![Page 11: Geology Plate Tectonics: A Scientific Theory Unfolds from Continental Drift](https://reader036.vdocuments.site/reader036/viewer/2022062423/5697bf871a28abf838c8890b/html5/thumbnails/11.jpg)
Alfred Wegener
• Young German meteorologist
• First proposed continental drift in1915
• Published 2 articles:• The Origin of Continents and Oceans • Theory of Continental Drift
![Page 12: Geology Plate Tectonics: A Scientific Theory Unfolds from Continental Drift](https://reader036.vdocuments.site/reader036/viewer/2022062423/5697bf871a28abf838c8890b/html5/thumbnails/12.jpg)
Continental drift hypothesis Scientific Process
• Wegener
•1st scientist to go out an look for evidence of continental separation •Use of the Scientific method
![Page 13: Geology Plate Tectonics: A Scientific Theory Unfolds from Continental Drift](https://reader036.vdocuments.site/reader036/viewer/2022062423/5697bf871a28abf838c8890b/html5/thumbnails/13.jpg)
Continental Drift
Figure 15.2
•Wegener stated that:•Continents move apart and together over time•All continents moved together about 300 mya
•They formed a supercontinent - Pangaea•They began breaking apart about 200 mya•Continents "drifted" to present positions •Continents "broke" through the ocean crust
![Page 14: Geology Plate Tectonics: A Scientific Theory Unfolds from Continental Drift](https://reader036.vdocuments.site/reader036/viewer/2022062423/5697bf871a28abf838c8890b/html5/thumbnails/14.jpg)
Continental Drift Hypothesis
Wegener used four lines of evidence to support his hypothesis:
1. Continental Puzzle
2. Matching fossils on continents
3. Matching mountain ranges across the Atlantic Ocean
4. Ancient climate • N. Continents located over the equator• S. Continents covered in giant ice sheet
![Page 15: Geology Plate Tectonics: A Scientific Theory Unfolds from Continental Drift](https://reader036.vdocuments.site/reader036/viewer/2022062423/5697bf871a28abf838c8890b/html5/thumbnails/15.jpg)
1) The Continental Puzzle
• Wegener• Saw a similarity between the coastlines on opposite sides of the South Atlantic Ocean.• Thought that the continents likely had been joined. • Used present-day shorelines to show how the continents fit together. • Where did he get this idea from?
•Ortelius and Pellegrini
![Page 16: Geology Plate Tectonics: A Scientific Theory Unfolds from Continental Drift](https://reader036.vdocuments.site/reader036/viewer/2022062423/5697bf871a28abf838c8890b/html5/thumbnails/16.jpg)
2) Fossil Evidence
• Several fossil organisms found on different landmasses• Organisms could not have crossed the vast oceans presently separating the continents • Organisms evolving on separate continents does not fit with Natural Selection
![Page 17: Geology Plate Tectonics: A Scientific Theory Unfolds from Continental Drift](https://reader036.vdocuments.site/reader036/viewer/2022062423/5697bf871a28abf838c8890b/html5/thumbnails/17.jpg)
3) Matching Mountain Ranges
Rock types and structures match• Appalachian Mountains eastern side of North
America into Newfoundland • Similar in age and structure in the British Isles
and Scandinavia.• Landmasses form a nearly continuous belt.
![Page 18: Geology Plate Tectonics: A Scientific Theory Unfolds from Continental Drift](https://reader036.vdocuments.site/reader036/viewer/2022062423/5697bf871a28abf838c8890b/html5/thumbnails/18.jpg)
4) Ancient Climates•Northern Continents
•Likely located over the equator•Evidence:
•Found coal deposits formed from tropical plants.
•Southern Continents•Ice sheets likely covered large areas of S.Africa, S.America, India and Australia. •Evidence:
•Layers of glacial till•Scratched and grooved bedrock carved by the ice
![Page 19: Geology Plate Tectonics: A Scientific Theory Unfolds from Continental Drift](https://reader036.vdocuments.site/reader036/viewer/2022062423/5697bf871a28abf838c8890b/html5/thumbnails/19.jpg)
4) Ancient Climate Continued.
Assumption: •Tropical forests would not exist in the Northern hemisphere at the same time as a glacial ice sheet covering most of the southern hemisphere•Instead: present day northern continents were nearer the equator and all continents were connected
![Page 20: Geology Plate Tectonics: A Scientific Theory Unfolds from Continental Drift](https://reader036.vdocuments.site/reader036/viewer/2022062423/5697bf871a28abf838c8890b/html5/thumbnails/20.jpg)
Summary