Continental DriftContinental Drift

be able to describe the Continental Drift Theory

be able to describe the evidence for the Continental Drift Theory including:Jigsaw puzzle fit of continentsGeological structuresFossilsClimatic evidence

This theory was proposed by Alfred Wegener, a German scientist about 100 years ago.

He hypothesized that the continents were not always in the same location that they are today, but that they have “drifted” there over millions of years.

He proposed that millions of years ago – the continents were all attached in one “super-continent” called PANGAEA.

In Greek:Pan – means “all” Gaea means “Earth”

His theory of what happened…

250 million years ago, was Pangaea

220 million years ago… it started to drift apart.

Continental Drift Theory

• the continents are still moving today

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#1:#1: He looked at maps of the world and noticed all the continents looked like puzzle pieces that “fit together”.

North North AmericaAmerica

South South AmericaAmerica

AfricAfricaa

Mountain Ranges: He noticed that mountain ranges that began on one continent, then ended at the coast-line, seemed to continue on another continent across the Ocean!

Rock structures: such as Folds in the Earth’s crust, and the types of rocks were similar on different continents

Eg. Rocks found in Newfoundland (North American continent) are the same type and age as rocks found in Greenland and Ireland/Scotland (European Continent)

Giant’s Causeway(Ireland and Scotland)

Wegener found that similar fossils are found on different continents despite the continents being separated by vast oceans How did the creatures get between the

continents? Creatures could not swim or fly that great

of distance

Most likely explanation = continents were closer together at some point in time

One fossil that intrigued him was Mesosaurus (a sharp-toothed freshwater reptile). These fossils have only been found in 2 places – Southeastern “South America” and Southwest “Africa”

There were many other fossils where he found the same thing.

Gossopteris (a fern). It’s fossils were found on every continent including Antarctica…It can’t grow in cold temperatures, so Antarctica must have been warmer millions of years ago because it must have been closer to the equator.

Cynognathus and Lystrosaurus (land dwelling creatures) Fossils found on different continents. They could not have swam that far to get onto different continents …so the continents must have been joined.

Paleoglaciation Rock markings left behind from ancient

glacierssuggest tropical regions may have once been

more polar(allowing for the formation of glaciers) This suggests that the continents were once

closer together

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Coal deposits coal is formed from decay of tropical

plants coal deposits are found in Antarctica

suggests Antarctica was once a tropical

climate that was closer to the equator

1) Map show that continents fit together like ________ ________ puzzle pieces

2) __________ _________ that seem to be split between 2 distant continents Mountain ranges

3) _________ found on different continents Fossils

4) ______________ pattern that makes sense if continents were once connected Paleoglaciation