What evidence proved that South America, Africa, India, and Australia were once covered by glaciers? –
reversals of Earth’s magnetic field are recorded by rocks in strips parallel to the ridges
.
What evidence shows that Africa and South America were once connected?
To him,
the presence of identical fossil species along the coastal parts of Africa
and South America was the most compelling evidence that the two continents were once joined.
What did evidence of ancient ice sheets in Africa South America India and Australia suggest to Wegener?
Alfred Wegener investigated this field and found
an anomaly in the Permo-Carboniferous ice sheet that was found through glacial till deposits to have once covered all the southern major plates
. … This aided Wegener’s theory that the continents were once all joined as a single landmass.
What evidence did Alfred Wegener find using glaciers?
Wegener used
fossil evidence
to support his continental drift hypothesis. The fossils of these organisms are found on lands that are now far apart. Grooves and rock deposits left by ancient glaciers are found today on different continents very close to the equator.
Why did no one believe Wegener’s theory?
The main reason that Wegener’s hypothesis was not accepted was
because he suggested no mechanism for moving the continents
. He thought the force of Earth’s spin was sufficient to cause continents to move, but geologists knew that rocks are too strong for this to be true.
Who discovered seafloor spreading?
Harry Hess
was a geologist and Navy submarine commander during World War II. Part of his mission had been to study the deepest parts of the ocean floor. In 1946 he had discovered that hundreds of flat-topped mountains, perhaps sunken islands, shape the Pacific floor.
Why was Pangaea not accepted?
Despite having this geological and paleontological evidence, Wegener’s theory of continental drift was not accepted by the scientific community, because
his explanation of the driving forces behind continental movement
(which he said stemmed from the pulling force that created Earth’s equatorial bulge or the …
How South America and Africa fit together?
The east coast of South America and the west coast of Africa seem to fit together
like pieces of a jigsaw puzzle
, and Wegener discovered their rock layers “fit” just as clearly. South America and Africa were not the only continents with similar geology.
What was the response to Wegener’s hypothesis?
“That was always his response:
Just assert it again, even more strongly
.” By the time Wegener published the final version of his theory, in 1929, he was certain it would sweep other theories aside and pull together all the accumulating evidence into a unifying vision of the earth’s history.
What are the 4 evidences of continental drift?
They based their idea of continental drift on several lines of evidence:
fit of the continents, paleoclimate indicators, truncated geologic features, and fossils
.
Where is Earth’s heat energy most concentrated?
Where Do We Find Geothermal Energy? Although heat from the center of the Earth is migrating to the surface everywhere, the heat is concentrated at
the edges of tectonic plates
.
What are two pieces of evidence for seafloor spreading?
Several types of evidence from the oceans supported Hess’s theory of sea-floor spreading-
evidence from molten material, magnetic stripes, and drilling samples
. This evidence also led sci- entists to look again at Wegener’s theory of continental drift.
What was missing from the continental drift theory?
The greatest problem facing Wegener was the lack of
direct evidence for the movements of continents
(no GPS at the time!) and no mechanism was known to be powerful enough to move entire continents.
What year did Pangea split?
The supercontinent began to break apart
about 200 million years ago
, during the Early Jurassic Epoch (201 million to 174 million years ago), eventually forming the modern continents and the Atlantic and Indian oceans.
What do Earth’s plates move on top of?
In plate tectonics, Earth’s outermost layer, or lithosphere—made up of the crust and upper mantle—is broken into large rocky plates. These plates lie on top of
a partially molten layer of rock called the asthenosphere
.
What are the 4 steps of seafloor spreading?
- Magma comes out of the rift valley.
- Magma cools to rock and hardens.
- Rock is pushed away as new rock is formed at MOR.
- Oceanic crust and continental crust meet at the trench.
- Oceanic crust bends down under the continental crust.
- Gravity pulls rock towards mantle.
- Rock melts to mantle.
