9.1 Moving Continents Flashcards
Why earthquakes happen? Why volcanoes exist? What causes tsunamis? Why volcanoes are found in some places and not others? What makes mountains form?
Name of the large landmass?
Pangaea
Who theorized “that the continents were one connected to each other. - must have somehow separated and drifted across the oceans.”
Alfred Wegener (1880 - 1930)
Explain Alfred Wegener’s first observation.
The continents seemed to fit into each other, like a jigsaw puzzle.
Explain Alfred Wegener’s second observation.
That fossils of the same prehistoric species were found on continents that were a long way apart.
What ridge ran the entire length of the Atlantic Ocean?
The Mid Atlantic Ridge
What was the name of ridges that have a series of huge cracks along them?
Rifts
What is seafloor spreading?
When new rocky crust was being formed at ocean ridges, following and spreading outwards.
Magnetic Striping?
Many rocks on the seafloor contained magnetic iron oxide, which had a north and south-seeking pole. Like compasses, they would either move north or south.
What is “age of the seafloor”?
The further the rocks of the sea floor were from the ridges, the older they were. This exactly what you would expect if new rocks form near the mid-ocean ridge and move outwards away from it.
Sediment thickness?
Layers of the crust became thicker as they moved away from the ridges
What is the scientific name of Tectonic plates?
Lithosphere
What is the semi-liquid rock in the upper mantle called?
Asthenosphere
Are crusts bigger than the continents?
Yes.
