Evidence for Continental Drift
Take a look at a map of Earth’s surface. Look carefully at
the shape of each continent. The continents look like they
might fit together like pieces of a puzzle, don’t they? People
throughout history have noticed this and wondered what it
meant. For example, over 400 years ago Abraham Ortelius, a
Dutch mapmaker, noticed that the coastlines of South
America and Africa fit together.
Have you ever been to Pangaea?
In 1912, a German scientist named Alfred Wegener
(VEG nur) proposed that the continents did at one time fit
together. He suggested that all the continents were once
connected. Wegener said they were once one big landmass.
He called this landmass Pangaea (pan JEE uh), which
means “all land.”
According to Wegener, about 200 million years ago, Pangaea
broke into pieces. The pieces drifted away from each other.
We call these pieces continents. Wegner’s hypothesis is called
continental (kahn tuh NEN tul) drift. Continental drift is
the hypothesis that Pangaea broke apart into continents that
moved slowly to where they are today. So even though you
haven’t visited Pangaea, the area where you live probably
was part of Pangaea millions of years ago
Did everyone accept Wegner’s idea?
Wegener’s hypothesis on continental drift was a
controversial idea. It caused a lot of argument. Wegener
didn’t convince people that his ideas were right during his
lifetime. He didn’t have enough evidence. For example, he
couldn’t explain what made the continents drift. He thought
Earth spinning on its axis might cause the continents to
plow through the ocean floor. But geologists and physicists
of that time rejected this explanation. Wegener’s basic idea
wasn’t accepted until long after his death in 1930. More
evidence came later to support his ideas.
How do animal fossils support continental drift?
Animal fossils offer one clue that the continents might
have been joined together millions of years ago. Fossils are
the remains, imprints, or traces of prehistoric organisms.
Fossils can tell when and where organisms once lived and
how they lived. For example, fossils of Mesosaurus have been
found in South America and in Africa. Mesosaurus is a
reptile that lived on land and in fresh water. How could this
reptile move between two continents separated by a salty
ocean? It is not likely that it swam across the Atlantic
Ocean. Wegener’s hypothesis of continental drift proposes
that Mesosaurus lived on both continents when they were
joined together. The map on the next page shows where
fossil remains of different animals have been found on
How do plant fossils support continental drift?
Another fossil that supports continental drift is
Glossopteris (glahs AHP tur us). Fossils of this plant are
found on five continents—Africa, Australia, Asia, South
America, and Antarctica. Finding Glossopteris in so many
areas supported the idea that all of these regions once were
connected and had similar climates.
What do climates tell us about continental drift?
Scientists have found fossils of warm-weather plants on
the island of Spitsbergen in the Arctic Ocean. This is one of
the coldest places on Earth. How did this happen? Wegener’s
hypothesis of continental drift proposes that Spitsbergen
Island drifted to the Arctic from a tropical region of Earth.
How do rocks support continental drift?
Glaciers are large, slow moving bodies of ice on land.
Glaciers leave tracks as they move, scouring and polishing
rock surfaces under them. They also leave deposits of glacial
rock and sediment. Glaciers are found in cold areas. Yet
there are traces of glaciers and deposits in many tropical
and temperate regions of Earth. How is this possible?
Wegener’s hypothesis of continental drift says that millions
of years ago, some tropical and temperate lands had cold
climates and were located near Earth’s south pole. These
continents were joined together and partly covered with ice.
When the continents drifted apart into warmer climates, the
glaciers melted away from these areas. The glacial deposits
left behind add more evidence to support continental drift.
What do rocks tell us about continental drift?
If the continents were connected at one time, then the
rocks located where the land broke apart should be similar.
Similar rock structures are found on different continents.
For example, rock structures found in the Appalachian
Mountains of the eastern United States are similar to rock
structures found in Greenland and western Europe. Some
rock structures from eastern South America are similar to
rock structures in western Africa. Rock clues like these
support the idea that the continents were connected in the
How could continents drift?
Wegener used clues found in rock, fossil, and climate to
support his hypothesis of continental drift. The computer
model below shows how the continents might have drifted
over millions of years. But Wegener was not able to explain
why the continents broke apart. Most importantly, he could
not explain what caused the continents to drift. Wegener
hypothesized that the continents plowed through the ocean
floor. He thought that the spinning of Earth on its axis
might have been the cause. He couldn’t prove his ideas with
facts. Physicists of his day thought he was wrong. The idea
was rejected because it was too unusual.
Today, there is more evidence for continental drift. After
Wegener’s death, new technology provided new evidence.
New ideas about continental drift were developed. One of
these ideas is called seafloor spreading. You’ll read about this
in the next section.