Case 5 · Free · Geology
Continental drift: How do we know the continents moved?
In the app: “The Continents That Wandered”
South Atlantic Ocean · 290 million years ago to today
Why this question matters
Alfred Wegener proposed in 1912 that the continents had once been joined, and most geologists rejected the idea for decades. It was accepted only after new evidence came from the ocean floor in the 1960s. It is a classic example of how a scientific idea moves from the fringe to the textbook.
The case briefing
In 1912 Alfred Wegener said the continents had once been joined. Most geologists laughed. Gather the clues that eventually proved him mostly right.
The evidence
The exhibits you examine in this case, labelled by the kind of evidence each one is.
- Written later1915
Wegener's book
Die Entstehung der Kontinente und Ozeane
Wegener pointed to matching coastlines, matching rocks and matching fossils on opposite sides of the oceans. He could not explain what force moved the continents.
- Scientific findingc. 290 million years old
Mesosaurus fossils
Southern Africa and South America
A small reptile that lived in fresh or shallow coastal water. Its fossils are found on both sides of the South Atlantic, but it could not have swum across an open ocean.
- Scientific findingExplained in 1963
Seafloor magnetic stripes
Vine and Matthews, Nature
Rock on both sides of mid-ocean ridges records flips in Earth's magnetic field as matching stripes. New seafloor forms at the ridge and spreads outward, pushing continents apart.
- Scientific findingc. 299–252 million years old
Glossopteris plant fossils
South America, Africa, India, Antarctica, Australia
Fossils of the same seed fern appear on five southern landmasses that are now separated by oceans.
How the investigation works
After the briefing and exhibits, you complete three steps. Every answer is explained, and the verdict lists the sources.
- 1
Chronology
Put the events back in order, oldest first. BC and AD are handled correctly, and there is no year zero.
- 2
Source comparison
Two sources, several statements. Decide which source supports each one, or whether neither does.
- 3
Supported conclusions
Sort claims into supported, going beyond the evidence, or contradicted. Every answer explains why.
What is still unknown
How plate tectonics began on the early Earth, and what mainly drives plates today, are open questions.
Sources
Case content last checked 2026-10-13. Not reviewed by an independent historian. Found an error? Tell us.
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