2. Alfred Wegener
• He was an astronomer of 20st century.
• He noticed that some places were
separating from each other while in other
parts of the globe were places bringing
closer.
• He proposed that the continents we know
today were once all attached in a single
landmass called…
3. Pangaea
• In the past, all the continents formed a
single one: Pangaea.
• Because of some force* they separate
from each other and nowadays have their
actual position.
• To test his hypothesis he gave some kinds
of evidences
4. Evidences
• Shape of continents:
South America and Africa.
• Fossil evidence on the shape of continents:
• Matching rock types.
• Geologic structures.
• Ancient climate partners.
5. But…
• He did not answer what induce it: the force
what induces the displacement of
continents.
• So, his theory did not came up.
6. How was the theory accepted?
• Arthur Holmes published his idea that
thermal convection in earth’s mantle
bankrupts the mantle and makes moving
landmasses, continents.
7. How was the theory accepted?
• Holmes suggested that the continents
didn't move but were ‘carried’.
8. And in World War II
• Discoveries of the Mid-Ocean Ridge and
the work of Harry Hess and others led to
the development of plate tectonics.
• After that the theory of Continental Drift
was engaged wide acceptance.
