6.2 Continental Drift
Lesson Objectives
- Be able to explain the continental drift hypothesis.
- Describe the evidence Wegener used to support his continental drift idea.
- Describe how the north magnetic pole appeared to move, and how that is evidence for
continental drift.
Introduction
An important piece of plate tectonic theory is the continental drift idea. This was developed
in the early part of the 20th century, mostly by a single scientist, Alfred Wegener. His
hypothesis states that continents move around on Earth’s surface and that they were once
joined together as a single supercontinent (Figure6.6). Wegener’s idea eventually helped
to form the theory of plate tectonics, but while Wegener was alive, scientists did not believe
that the continents could move.
The Continental Drift Idea
Find a map of the continents and cut each one out. Better yet, use a map where the edges of
the continents show the continental shelf. In this case, your continent puzzle piece includes
all of the continental crust for that continent and reflects the true size and shape of the
continent. Can you fit the pieces together? The easiest link is between the eastern Americas
and western Africa and Europe, but the rest can fit together too!
Alfred Wegener, an early 20thcentury German meteorologist believed that the continents
could fit together. He proposed that the continents were not stationary but that they had
moved during the planet’s history. He suggested that at one time, all of the continents had
been united into a single supercontinent. He named the supercontinent Pangaea, meaning
entire earthin ancient Greek. Wegener further suggested that Pangaea broke up long ago
and that the continents then moved to their current positions. He called his hypothesis
continental drift.
Evidence for Continental Drift
Besidesthefitofthecontinents, Wegenerandhissupporterscollectedagreatdealofevidence
for the continental drift hypothesis. Wegener found that this evidence was best explained if
the continents had at one time been joined together.
Wegener discovered that identical rocks could be found on both sides of the Atlantic Ocean.