Plate Tectonics for Chapter 10 Flashcards
What is continental drift?
Continental Drift is the process of the continents moving apart over millions of years.
This is a theory by Alfred Wegener
What were the two reasons that supported the theory of continental drift?
The two supporting reasons for this include:
- Continents fit together like a jigsaw
- Fossils of the same species found on continents far apart
Describe the seafloor spreading process
Seafloor spreading is when new crust is formed at the ridge and spreading outwards.
This was a proposed hypothesis by Hess, an American geologist and gave a technical explanation to back up the theory of seafloor spreading.
What is the underwater mountain ridge running right around the world called?
It is called the Great Global Rift System because there are heaps of rifts (cracks) in this ridge.
What were the two proposals by the American geologist, Hess?
- Seafloor spreading
- Subduction occurs in other places
(ocean trenches)
What is sinking crust called?
sinking crust is called subduction
Briefly explain what magnetic striping is.
Magnetic Striping is:
when molten rock solidifies and the magnetite particles face North to South according to the Earth’s magnetic field.
Magnetic striping occurs when patterns of strips of rock have alternating magnetism and would also be symmetrical on either side of the ridge.
What is magnetite?
Magnetite is a rock that will behave like a compass and have a north-seeking pole.
When the molten rock solidifies, all of the magnetite particles line up in the same direction.
Why does the direction of magnetite change every few million years?
Direction of magnetite changes because the Earth’s magnetic field changes every few million years.
How does the magnetic striping support the seafloor spreading theory?
The pattern of magnetic striping is symmetrical on either side of the rift
The further away the rock is from the rift, the …….. and ……… it is.
older and thicker
The scientist who proposed continental drift was…
Alfred Wegener
The scientist who proposed seafloor spreading was…
Harry Hess
Magnetic striping makes symmetrical stripes on either side of the ridge because…
the Earth’s magnetic field changes, and at that time, the magnetite particles alternate to create stripes.
It is the same on either side because seafloor spreading occurs on both sides of the ridge.
Which observation led to the discovery of magnetic striping and seafloor spreading?
An observation of weak and strong magnetism on the sea floor by warships in WWI led to the discovery of magnetic striping and seafloor spreading.
