The Restless Earth Flashcards
Describe the characteristics of the Earth’s CORE:
7000 degrees, solid iron and nickel ball.
Describe the characteristics of the Earth’s MANTLE:
Semi-molten rock, moves very slowly and has convection currents. Tectonic plates float on top of it.
Describe the characteristics of the Earth’s CRUST:
20km thick, divided int plates. Two types of crust: continental and oceanic.
Why do the plates move?
There are convection currents in the mantle nderneath
Describe the characteristics of continental crust:
Made of granite, much older (up to 3.8 billion years old), less dense, not renewable, can’t be destroyed, much thicker.
Describe the characteristics of oceanic crust:
Made of basalt, much younger (less then 200million years old) more dense, renewable, can be destroyed, much thinner.
Name at least 3 major tectonic plates
- Pacific
- North American
- Indo Australian
- Eurasian
- Nazca
- African
Name the 4 types of plate boundary:
- Constructive
- Destructive
- Conservative
- Collision
Describe what happens at a Constructive plate margin:
2 plates move away from each other, leaving a gap for magma to rise up through.
Describe what happens at a Destructive plate margin:
Oceanic crust descends below less dense continental crust. It is melted due to friction, forming magma, which can then rise through holes in the continental plate and form volcanoes.
Describe what happens at a Conservative plate margin:
Two plates move past each other in a parallel motion.
Describe what happens at a Collision margin:
Two plates of the same density are pushed together. Because neither one can be subducted, they buckle and form fold mountains.
At which plate margin(s) will you find earthquakes?
All of them.
At which plate margin(s) will you find volcanoes?
Constructive and Destructive.
What are the 4 pieces of evidence for Wagner’s continental drift theory?
- Fossil evidence
- ‘Puzzle fit’
- Paleomagnetism
- Mineral patterns
At which 2 boundaries can fold mountains form?
Destructive and collision
Why can fossils of sea creatures sometimes be found at the summits of fold mountains?
If there is sea between two plates as they move together at a collision boundary, sediment from the sea floor can be pushed up when the two plates come together, and as they’re compressed into sedimentary rock to form the fold mountains, fossils are also formed.
Name some human uses of fold mountains:
- Agriculture
- Hydro electric power
- Tourism
- Settlement
- Railways
- Quarries