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STAG1032: PHYSICAL GEOLOGY (Geologi Fizik)

Continental Drift Concept (Konsep Hanyutan Benua)

Hypothesis die Verschieburg der Kontinente

Dr. Wan Zuhairi Wan YaacobProgram Geologi, UKM

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Konsep Hanyutan Benua(Continental Drift Concept)

Teori Tektonik keping(Plate Tectonics Theory)

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Untold tragedies of Continental Drift.

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!!!!??

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Point to ponder

“Did the continents originate at their present locations or did they drift to where they are today?"

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Continental Drift

• Late 19th century; Edward Suess– Austrian Geologist– 1885: proposed the name Gondwanaland– Gondwana: supercontinent composed of

southern landmasses.• 1910: F.B. Taylor

– Geologist– Published a paper on Continental Drift– Little supporting evidence – small impact

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Continental Drift

• 1915: Alfred Wagener– German Meteorologist & Geophysicist– Published a book “The Origin of Continents

and Oceans”– Developed the hypothesis of Continental

Drift– “all the continents had at one time been

united into single super-continent”

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Alfred Wegener, a German meteorologist

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Concept of Continental Drift

• 225-200 million years ago (Permian to Jurassic):

– Single supercontinent (Pangaea = All Land)– Panthalassa (Pan =all; thalassa = sea)

• The Evidence: – 1. Continental fit (South America v Africa)– 2. Glacial Evidence / Ancient climates– 3. Geographic distribution of fossils– 4. Similarities of rocks and mountain

ranges / structures

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Gondwanaland

Laurasia

Key words:--

1. Pangaea2. Panthalassa3. Laurasia4. Gondwanaland

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1. Continental fit (Jigsaw Puzzle)

• Similarity between coastlines: South America and Africa.

• Critics: modification by erosion & deposition

• But fit along the true geologic margin i.e. continental shelves (pelantarbenua) (continental // oceanic crust) –depth of 900m-2000m.

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Continental fit along true geologic margin which is located along the margin of continental and oceanic crust (900-2000m)

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A stamp commemorates the concept of Continental Drift

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2. Glacial Evidence / Ancient climates

• Glacial deposits (till) & striations during Permian period (220-250 million years)

• Striations = scratch marks on bedrock beneath the till

• Southern hemisphere – highly glaciated

• Northern hemisphere – tropical climate (based on plant fossils)

• ICE: Present ocean to land (wrong!!); land to ocean

• Therefore, located near the South Pole

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Striations or scratch marks- Evidence of an ice movement

rock

Glacial till

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The continents as there are today. Evidence of old ice sheets

Equator(tropical climate)

If continents did not move:1. How glaciers moved from ocean to land?2. How large-scale continental glaciers formed near the equator?

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If continents are reassembled as a single landmass with South Africa located at the south pole, the direction of continental glaciers movement makes sense (i.e. glacier moved radially outward from the pole)

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3. Fosil Evidence

• Land Bridge South America – Africa– No remnants were found

• Glossopteris flora • Mesosaurus

– Small freshwater reptile– Permian age rocks – Brazil and South

Africa.• Lystrosaurus & Cynogathus

– Triassic aged land dwelling reptiles• Thesaurus (???)

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• Thesaurus– Small dinosaur with so many words !!

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Land Bridge

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Small freshwater reptile

Triassic aged land dwelling reptiles

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4. Rocks & Mountain ranges

• Picture puzzle– Fitting & picture

• Wagener : “Torn pieces of a newspaper”

• Same age /structure/style of deformation

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The trend of Appalachian Mountains

App. Mountains terminate abruptly at the Newfoundland coastline

Mountain ranges of the same age and deformational style appear in another places

Continuous mountain range when continents position next to each other

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Similar rock sequence for all continents in Gondwanaland.

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One problem with the hypothesis

Its lack of a mechanism to explain howcontinents, composed of granitic rocks, could move through the denser basaltic oceanic crust??

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THE END