Who Invented the Theory of
Continental Drift?
FOUNDERS
Many people believe that Alfred Wegener invented
the theory of continental drift, but he didn't. He just played a major role
in proving it. As early as 1620, people like Francis
Bacon were noticing how similiar the west coast of Africa and the east
coast of South America were, and how they appeared to fit together.
In 1800, a German botanist,
Alexander Von Humbolt,
came up with the theory of continental drift. He too noticed how Africa
and South America seemed to fit together and wondered if they were once
joined. Later in 1858, Antonio Snider-Pellegrini, a Frenchman, showed how
Africa and South America might have once been a single landform but later
separated by using maps. He also noticed how similiar fossils were in North
America and Europe and suspected they too were once joined. To explain the
beginning of mountains, Frank B. Taylor used the theory of of continental
collisions in 1908. In the early 1900's, Wegener also suggested that all
of the continents could have once been a single continent.
Alfred Wegener was a lecturer in astronomy
and meteorology.
In the fall of 1911, when he was 31,he was at the University of Marburgs
library, in Germany, when he happened to pick up a scientific paper. This
paper supported the idea that there was a land bridge between Brazil and
Africa. Before this, Wegener had been familiar with the idea that the continents
move, but it was not until he found this article that he was intrigued.
The evidence shown in the paper included descriptions of fossils that were
the same, of animals and plants that could not have survived the long journey
across the Atlantic Ocean. After reading the article, he began to search
for more research papers for extra information. As Wegener learned that
animals that were as different as snails and monkeys, and plants that were
as different as heather and ferns existed in areas that were now so widely
separated, he was taken over by a previous speculation. Wegener, like hundreds
of scientists before him, remembered how the Atlantic coasts of South America
and Africa fit together like a puzzle piece
and wondered if the continents had once been a single land mass.
PANGAEA
In 1912, Wegener guessed that the continent of Pangaea, meaning all lands,
was around 225 million years ago.
1. 200 million years ago
2. 160 million years ago
3. 80 million years ago
4. the present
Laurasia was the name given to the northern part of Pangaea and Gondwanaland
was the southern part. Pangaea, it is said, covered half of the Earth's
surface and was surrounded by an ocean called Panthalassa, which means universal
sea. There are many pieces of evidence that suggest that Pangaea once existed.
First, the continents, especially South America and Africa seem to fit together
like a puzzle. Second, Alfred Wegener noticed that plant and animal fossils
from the Paleozoic age were very similiar, yet they were found on different
continents.
This suggests that they once all lived together when the continents were
together. Huge belts of rocks were found in Africa and South America were
identical. Not only were they the same, but would match up if the continents
were put together. That was the third piece of evidence. Fourth, Wegener
also knew that around 300 million years, a continental ice sheet covered
parts of southern Africa, South America,southern Australia, and India.
There is proof that glaciers moved from Africa, through the Atlantic Ocean,
and then on towards South America. This would be much easier if the Atlantic
Ocean were not there. Fifth, if it were cold enough in the southern continents
for ice, then why isn't there any evidence of ice in the northern continents?
It's very simple. The northern continents of today are not where they were
300 million years ago. Then, they were at the equator which is indicated
by deserts and coral reefs. Also the earliest marine deposits found along
the Atlantic coasts are only in Jurrasic age. This proves that the body
of water did not exist before then. Wegener believed that Pangaea split
up during the Mesezoic era. The pieces of it, the continents we know today,
slowly took their present conditions.
The time of the major collision between South Asia and India is unknown,
but estimated. The estimates range from 38 million to 66 million years ago.
Now studies of the layers of rocks in Pakistan have shown that the major
part of the collision happened from 55 million to 66 million years ago.
The discovery was the key because inside of three layers of rocks, fossilized
marine organisms were found. Since Paleobiologists
know when these organisms evolved and became extinct, they could date the
rock in which they were found. The earliest, 66 million years old, showed
that a deep ocean trench was located between the two continents. When the
Indian land mass moved north, the trench was erased. By the time of the
second layer, 55 million years old, only a shallow sea lay between them.
Some say that around 49 million years ago a small mountain range, later
replaced by the Himalayas, formed between the land masses. Then the mountains
wore down to what was then a moat where whales used to live. Later the two
continents fused together for good.