Transcript Drifting Continents

DRIFTING CONTINENTS
DRIFTING CONTINENTS
Do you
see the
pieces of
the
jigsawpuzzle?
DRIFTING CONTINENTS
DRIFTING CONTINENTS
Theory of Continental Drift – Alfred
Wegener’s theory that all continents
were once one landmass called Pangaea
(theory proposed in 1910)
DRIFTING CONTINENTS
DRIFTING CONTINENTS
200-300 million years before present –
Pangea existed, and later, over tens of
millions of years, Pangaea breaks up to
form present landmasses
Continental Drift
What is the EVIDENCE? (proof)
What evidence is there that Pangaea even
existed?
There are 3 pieces of evidence:
1. Landforms
2. Fossils
3. Climate
DRIFTING CONTINENTS
Evidence from Landforms – Mountain
belts that match up in South Africa,
Argentina, and South America;
Coalfields in North America and Europe
match up
DRIFTING CONTINENTS
Glacial striations on
rocks show that
glaciers moved from
Africa toward the
Atlantic Ocean and
from the Atlantic
Ocean onto South
America. Such
glaciation is most
likely if the Atlantic
Ocean were missing
and the continents
joined.
DRIFTING CONTINENTS
DRIFTING CONTINENTS
DRIFTING CONTINENTS
Evidence from Fossils – Glossopteris
plant fossils found in Africa, South
America, Australia, India, & Antarctica;
these seeds are not designed to travel a
great distance or survive ocean travel
DRIFTING CONTINENTS
Glossopteris fossil found in
Antarctica.
DRIFTING CONTINENTS
DRIFTING CONTINENTS
Evidence From Climate – Island in Artic
Ocean called Spitsbergen has fossils of
tropical plants
DRIFTING CONTINENTS
The island of Spitsbergen
DRIFTING CONTINENTS
Rejection of Wegener’s Theory –
Wegener’s theory was rejected by most
scientists because he could not identify
the mechanism for HOW continents
drift
DRIFTING CONTINENTS
DRIFTING CONTINENTS
Question
How would you explain how the continents might
have moved? Why does heat transfer have
something to do with it?