Earth and the Atmosphere Flashcards
How many layers are there in the Earth’s crust and what are they (in order)?
- Inner core, outer core, mantle and crust.
What are the crust and upper mantle cracked into?
Large pieces called tectonic plates.
What can happen when tectonic plates meet?
Volcanoes and earthquakes.
What are the properties of the crust of the Earth?
It is relatively thin and rocky.
What are the properties of the mantle of the Earth?
It has the properties of a solid but can flow very easily.
What are the properties of the core of the Earth?
It is made from liquid nickel and iron.
What is continental drift?
Tectonic plates move a few centimetres every year. Though this may not seem like much, over millions of years this allows continents to shift thousands of kilometres apart.
Why do tectonic plates move?
Because of convection currents in the Earth’s mantle.
What are tectonic plates driven by?
The heat produced by natural decay of radioactive elements in the Earth.
Who was the theory of plate tectonics and continental drift proposed by?
Alfred Wegener
What was the theory of continental drift before Wegener?
it was thought that mountains formed because the Earth was cooling down, and in doing so contracted. This was believed to form wrinkles, or mountains, in the Earth’s crust.
What was Alfred Wegener’s theory?
He suggested that mountains were formed when the edge of a drifted continent collided with another. It took 50 years for Wegener’s theory to be accepted.
What are the two main types of tectonic plates?
Oceanic plates that occur under the oceans.
Continental plates that form on land.
What happens when tectonic plates meet?
The Earth’s crust becomes unstable as the plates slide past each other, push against each other, or ride under or over one another.
Why do some people choose to live near volcanoes?
Because volcanic soil is very fertile.
