Name: ________________________
CONTINENTAL DRIFT
pg. ___
Alfred Wegener – A German scientist who proposed the theory of continental drift in 1912
 Thought to himself: The western coast of Africa and the eastern coast of South America
seemed to fit together… like a land-puzzle…
CONTINENTAL DRIFT – the idea that Earth’s continents were once joined in a single
landmass and gradually moved, or drifted apart.
IN ORDER TO PROVE A THEORY…. YOU NEED EVIDENCE….
1.
FOSSILS – fossil findings of an ancient reptile, Mesosaurus, was found in South
America and Western Africa.
a. THE MESOSAURUS CANNOT BE FOUND ANYWHERE ELSE IN THE WORLD.
b. Wegener said that the fossils helped the theory that
South America and Western Africa were once attached.
c. Plant fossils were also found to help prove Wegener’s Continental Drift Theory –
Tropical plants found in Greenland – SUGGESTS CLIMATE CHANGE
2.
GEOLOGY – The types of rocks, rock structures (folds and faults), and mountain
ranges (formed in the original formation of Pangaea) are similar on other continents
 Example: Limestone layers in the Appalachian Mountains
3.
&the limestone in Scotland’s Highlands.
GLACIAL DEPOSITS - parallel "scrape" marks on rocks caused by moving glaciers
were found in warm climates like Africa, South America, and Australia.
PANGAEA!!!
This theory did not explain HOW the continents drifted apart, so his ideas were rejected until…
Name: ________________________
CONTINENTAL DRIFT
pg. ___
 The THEORY OF PLATE TECTONICS states that Earth’s lithosphere is made up of huge
plates that move over the surface of the Earth
 Tectonic Plates ARE LARGE AND SMALL SLABS OF ROCK (THE BROKEN LITHOSPHERE)
 The Earth’s Lithosphere is made up of moving plates


The theory of Plate Tectonics explains
how plates and their continents move.
Tectonic Plates include Oceanic Crust and
Continental Crust.
Evidence of Plate Tectonics:
o Sea-floor spreading, mid-ocean ridges, the age of the sea floor, and ocean trenches.
Why is this happening????
CONVECTION – is energy transfer by
the movement of a material
CONVECTION CURRENT – In the
ASTHENOSPHERE, the hot, soft rock
rises, cools, and sinks, then is heated
and rises again
 This is how the asthenosphere
moves the rock above it