1. The Earth's Structure Flashcards
How long ago did Planet Earth form?
About 4.5 billion years ago
What are the three main layers of Earth’s structure?
- Inner core
- Outer core
- Mantle
- Crust
What is the thickness of the inner core?
1,270 km
What is the temperature range of the inner core?
5,000 - 7,000 °C
What materials compose the inner core?
Solid metal - iron and nickel
What is the thickness of the outer core?
2,200 km
What state of matter is the outer core?
Liquid metal
What temperature range does the outer core have?
4,000 - 5,000 °C
What is the primary function of the outer core?
Creates the Earth’s magnetic field
How thick is the mantle?
2,850 km
What is the temperature range of the mantle?
1,000 °C near the crust to 3,700 °C near the core
What is the asthenosphere?
The upper mantle known for being ductile and semi-molten
What are the two types of crust?
- Oceanic crust
- Continental crust
What is the depth range of Earth’s crust?
3-70 km
Describe the oceanic crust.
Young, thin, dense, heavy, mostly basalt rock
Describe the continental crust.
Older, thicker, lighter, made up of different rock types but mostly granite
What generates heat in the Earth’s core?
- Frictional forces during formation
- Radioactive decay of elements
How much heat flows from the core into the mantle?
44 trillion watts
What is continental drift?
The process of large plates of the Earth’s crust moving
What is the average speed of plate movement?
2-5 cm a year
What are the three key factors that drive plate movement?
- Convection cells
- Ridge push
- Slab pull
What is mantle convection?
The slow creeping motion of the Earth’s solid rock caused by convection currents
What happens at rift zones?
The crust is moving apart under tensional stresses
What forms new ocean crust in the lithosphere?
Magma rising upwards through rift zones
What is ridge push?
The force that pushes older crust away from mid-ocean ridges
What are mantle plumes?
Upwellings of hot rock in the mantle
What is a hotspot?
Volcanic centres caused by mantle plumes
What is a flood basalt?
A giant volcanic eruption covering large stretches of land or ocean floor with basalt lava
What occurs during subduction?
The denser lithospheric plate sinks under another plate
What drives the process of slab pull?
The weight of the subducting plate and the force of gravity
True or False: Slab pull is considered the least important factor in plate movement.
False
