Continental Drift Theory. Simplified

2. Continental drift was a theory that
explained how continents shift
position on Earth's surface. Set forth
in 1912 by Alfred Wegener, a
geophysicist and meteorologist,
continental drift also explained why
look-alike animal and plant fossils,
and similar rock formations, are found
on different continents.

3. Based on the idea of Alfred
Wegener during the geologic
past, the continents was
connected forming a single
massive landmass, which he
named as Pangaea, that into
some continents and drifted to
their present positions.

5. The following are Wegener’s principal observations
about the The Origin of Continents and Oceans:

6. 1. Fit of the continents

8. 2. Distribution of Rocks

10. 2. Distribution of Rocks

11. 3. Distribution of fossils

13. 4. Paleoclimates

14. If continents drift is
true, what is
making them move

15. Theory was Rejected
•Wegener could not present/
explain the mechanism of
continental drift.

16. Harry Hess came up with an answer about the
explanation about continental drift. Hess proposed
that it was the seafloor itself that was pushing the
continents apart. The Mid-Atlantic ridge is an ocean
ridge found along the Atlantic Ocean floor. The
ridge, he thought, was where new seafloor was
being added to the earth's lithospheret. Hess called
it seafloor spreading.

18. A magnetic reversal occurs when the north and
south poles of the Earth's magnetic field flip or
switch positions . This is called a geomagnetic
reversal. The history of geomagnetic reversals is
preserved in older and younger rocks.

21. Plate tectonics unifies the concepts of
continental drift, seafloor spreading, and magnetic
field reversals, and other geological and geophysical
discoveries. The theory of plate tectonics states that
the lithosphere is not a continuous layer but
consists of several irregularly shaped pieces called
tectonic plates which may include an oceanic crust
or a continental crust or both.

22. The main difference between plate tectonics and
continental drift is that plate tectonics describes
the features and movement of Earth’s surface in the
present and in the past whereas continental drift
describes the drifting of Earth’s continents on the
ocean bed.