Supercontinent Detective
Name
Date
Objective: To evaluate the evidence used by Alfred Wegener and other scientists to reconstruct the
supercontinent of Pangaea and support the hypothesis of moving continents.
Background: In the early 1900’s, Alfred Wegener, a German meteorologist, suggested that the continents
were once joined together in a single landmass he called Pangaea, Greek for “all land”. He called the
surrounding ocean Panthalassa, which means “all seas”. Wegener was not the first person to look at a
map of the world and notice the apparent puzzle piece fit of continental coastlines, but he was the first to
really begin to collect evidence and build a scientific case to support his idea. He called his hypothesis
“continental drift” and envisioned the supercontinent of Pangaea gradually breaking into separate
landmasses that slowly moved to their present positions. Despite a large body of evidence used to
support his ideas, Wegener was unable to provide a viable explanation for how continental landmasses
could move, and his idea was largely disregarded by the scientific community of his time. However,
Wegener’s evidence eventually became the foundation of the now widely accepted theory of plate
tectonics.
In this activity, you will examine Wegener’s evidence and evaluate how well it supports his idea.
Puzzle Piece Fit of Continents
The world map below shows the current shapes of major landmasses. The gray shaded areas represent the
continental shelves. Remember that the continental shelves are composed of continental crust, not
oceanic crust, so they are technically part of the continents even though they are sometimes underwater.
Image from http://geology.uprm.edu/Morelock/8_image/shelv.jpg
1. Using only the shapes of the coastlines, describe which landmasses you think would fit reasonably
well together to form a supercontinent. Be specific – which coastlines of which continents would have
been connected?
2. Which landmasses are difficult to “fit into the puzzle” using only the shapes of the coastlines?
Explain why.
Matching Mountain Ranges
The map below shows the locations of some mountain ranges on opposite sides of the Atlantic Ocean.
Mountains marked with the same letter contain rocks and geologic structures of the same geologic ages.
All were formed during the Paleozoic Era, between approximately 540 and 250 million years ago.
1. Label the Caribbean, Ozark plateau, Appalachians, Atlas, Alps and E. Greenland, and Kjolen (along
Norway/Sweden) mountains on the map
2. Which mountain ranges might have been connected during the time of Pangaea?
3. Based on that information, which landmasses and coastlines must have been connected to each other
(name both the continents and the portion of their coastlines that would be connected)?
4. Given that these mountain ranges don’t continue across the Atlantic ocean floor, explain how they
support Wegener’s supercontinent hypothesis.
Climate Evidence
Sedimentary rocks record information about the environments where they accumulated and the overall
climate conditions during the time when they formed. Some examples of sedimentary rock deposits that
are important climatic indicators include:
• Glacial deposits such as thick mixtures of unsorted sediments called glacial till deposited by large
ice sheets, sometimes accompanied by glacial striations (scratches) carved into underlying rocks;
• Coal deposits formed from the burial and slow alteration of thick accumulations of plant material,
such as one might find in tropical swamps or jungles;
• Salt and sand dune deposits formed dry, subtropical deserts; and
• Limestone containing shells of tropical marine organisms, including coral reef deposits.
Alfred Wegener searched for evidence that helped him infer climates at the time of Pangaea and looked
for inconsistencies with modern climates.
The map below shows the distribution of different sedimentary rocks around the world that were
deposited during the Carboniferous Period, approximately 460 to 500 million years ago.
1. How does the distribution of glacial deposits around the world help support the idea that the
continents were once joined as one supercontinent?
2. What do the glacial deposits suggest about the past climate of these locations and what does this
suggest about the global positions of these continents in the past ?
3. What type of climate likely existed across the northern part of North America and Northern Europe
during the Carboniferous? How can you tell? Is this consistent with the modern climate zones of
those regions? Explain your answer.
Fossil Evidence
Climate plays an important role in determining the types of plants and animals that can live in a region,
and fossils of once-living organisms preserve important evidence of past climates. Wegener plotted
locations of fossils several land-dwelling or fresh-water animals that lived during the late Paleozoic and
early Mesozoic eras. He also knew about findings of other fossil plants and animals from that time. He
examined the fossil evidence for patterns in distribution that would support his supercontinent hypothesis.
The map below summarizes some of the important fossil evidence used to reconstruct Pangaea.
Explanation and Map Key
M= Mesosaurus – small freshwater
reptile
L= Lystrosaurus – stocky, sheep-sized
plant-eating reptile
C= Cynognathus – small carnivorous
terrestrial reptile with mammal-like
traits
G= Glossopteris – seed-bearing fern,
grew
in large forests, often associated with
coal deposits; large seeds could not be
carried by wind or across oceans
1. Where are Mesosaurus fossils found today? Based on the description above of the fossil, how does its
distribution support Pangaea rather than land bridges or migration between continents?
2. Where were Glossopteris fossils found? Does it seem likely that the same kind of plant could live in
all of those locations today? Explain why or why not?
3.
Is it likely that the Glossopteris seeds could have been transported between those locations? Why or
why not?
4. Why would Alfred Wegener have concentrated his search for fossil evidence of terrestrial (land)
animals and plants such as those described above in order to provide support for the existence of
Pangaea?
CONCLUSION
If you had been a contemporary of Alfred Wegener, would you have been inclined to accept or refute his
hypothesis? Which evidence is most compelling for his argument? Explain why. What additional
evidence would have been helpful?