Transcript Continental Drift PowerPoint

Continental 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 continents
Geological structures
Fossils
Climatic 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 “supercontinent” 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
7

#1: He looked at maps of the world and
noticed all the continents looked like
puzzle pieces that “fit together”.
North
America
Africa
South
America

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
Giant’s Causeway
same type and age as rocks
(Ireland and Scotland)
found in Greenland and
Ireland/Scotland (European
Continent)

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 glaciers
suggest tropical regions may have once been more polar
(allowing for the formation of glaciers)
 This suggests that the continents were once closer
together
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
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1) Map show that continents fit together like
puzzle pieces

2) Mountain ranges that seem to be split
between 2 distant continents

3) Fossils found on different continents

4) Climatic patterns that make sense if
continents were once connected.
▪ Paleoglaciation
▪ Coal Deposits