Download Continental Drift

Continental Drift
Alfred Wegener
• In 1910, Alfred
Wegener became
curious about the
continents. He
formed a hypothesis
that the continents
had moved.
• Wegener’s hypothesis was that
all continents had been joined
together in a single landmass
and have since moved apart.
• He named this
super continent
Pangaea. This
idea was known
as Continental
Drift.
Evidence
• 1. Landforms
– Mountain ranges and other features
on continents provided evidence.
South America and Africa fit
together like puzzle pieces. A
mountain range in South America
lined up with a mountain range in
Africa. European coal fields
matched up with ones in North
America.
• 2. Fossils
–A fossil is a trace of an organism
preserved in rock. Fossils of the
reptiles Mesosaurus and
Lystrosaurus had been found in
places now separated by oceans.
Another example was the fernlike plant Glossopteris found in
Antarctica, Africa, South
America, Australia and India.
Two land masses that make up
Pangaea…
Laurasia: Northern Continents
Gondawanaland: Southern Continents
• 3. Climate
–Fossils of tropical plants
were found in Antarctica.
–Glaciers once covered South
Africa. Deep scratches from
the glaciers were found on
rocks.
Rejection of Wegener’s
Hypothesis
• Wegener could not provide
evidence for the forces that push
or pull the continents. Many
geologists in the 1900’s thought
the earth was slowly shrinking and
cooling. Wegener disagreed with
this proposal because mountains
usually appear in narrow bands
along the edge of continents
• Now scientists have new evidence to support the theory of
Continental Drift.
• The Ring of fire: shows that the plates were once
connected and Convection Currents in the mantle has
caused the movement and the eruption of volcanoes and
earthquakes.