CONTINENTAL DRIFT ANDPLATE TECTONICS

#1) What was probably the first evidence that led people to think

that the continents were once connected

Jigsaw Puzzle FitIt is likely that the first clue that the continents were once joined together came from the close fit between the west coast of Africa and the east coast of South America.

Studies have shown that the fit between the continents is actually in the range of 95% along the continental shelves.

#2a) What did Alfred Wegener mean by

“continental drift”?

Continental DriftContinental Drift theory says that 300 million years ago all of the continents came together and formed a super-continent called Pangea (all land).

This was followed by the break up of Pangea about 200 million years ago, and the drifting of the various continents to the positions that we see today.Here is what we may see in the future.

#2b) What proof did he have to support his theory?

Fossil CorrelationWegener found evidence of many fossils that were identical but scattered over different continents.

He believed that it was impossible for all of those lifeforms to have evolved identically on all these continents.

Instead, he saw this as proof that the continents were once all joined together.

Geologic FitThe Appalachian Mountains in North America and the Caledonian Mountains in Scotland are of the same age, made of the same rock type, and have the same appearance.

Wegener took this to mean they were in fact the same mountain range, but that they had become separated by the Atlantic Ocean in the last 200 million years.

Appalachian

Caledonian

Paleo-GlaciationWegener interpreted the glacial deposits and markings that can be found in tropical areas (including South America, Africa, India, and Australia) to mean that all of these regions had, at one time, been very close to the south pole and so had much colder climates.

200 million yrs B.P.

Present

#2c) Wegener was not able to convince most scientists of his day to accept continental drift because he could not explain how a continent could move through the hard rock of the earth’s crust.

Watch this Continental Drift video

Watch this Plate Tectonics video

#5) The movement of Earth’s plates has shaped Canada in

many ways. Explain.

Influence of tectonics on Canada

THE MOVEMENT OF TECTONICS PLATES HAS PROVIDED CANADIANS WITH MANY ECONOMIC AND LEISURE OPPORTUNITIES;

CANADA’S MOUNTAIN RANGES ARE THE RESULT COLLISIONS BETWEEN PLATES. THESE MOUNTAINS ARE SITES OF MUCH ECONOMIC ACTIVITY INCLUDING TOURISM (SKIING & SNOWBOARDING) , MINING, AND FORESTRY.

CANADA’S HUGE OIL, GAS, AND COAL DEPOSITS WERE FORMED WHEN CANADA WAS LOCATED MUCH CLOSER TO THE EQUATOR (IN THE TROPICS), BEFORE DRIFTING TO ITS CURRENT POSITION IN THE NORTHERN HEMISPHERE.

OUR POSITION IN THE NORTHERN HEMISPHERE ALSO GIVES US A CLIMATE WHICH IS IDEAL FOR THE AGRICULTURE AND FOREST REGIONS THAT WE POSSESS.