2.3 Layers of Earth

Layers of the Earth

Magnetic

What causesmagnetic fields?

How do compasses work?

What is the Lithosphere?

The lithosphere is the outermost layer, like the Earth's skin, and it includes the crust and upper part of the mantle.

What is the Mantle?

• Thickest layer (1800 miles thick)
• Has sublayers: The upper mantle, transition zone and lower mantle
• Composed of: hot, dense silicate rock (which acts like a viscous liquid/plastic solid known as magma in some regions)
• Temperature: 1600-4000 degrees F
• Layer where convection occurs!
• The primary mechanism within the mantle is convection
• hotter, less dense material near the core rises,
• and cooler, denser material nearer the crust sinks.
• The core is radiating out Thermal (Heat) Energy: heating the lower mantle

What is the Outer Core?

• A liquid layer made of iron and nickel.
• Composed of hot, liquid metal (mostly melted nickel and iron). Ranges from 4000-9000 degrees F.
• 1400 miles thick.
• This is what causes Earth’s magnetic field!

What causes Magnetic Fields?

• The Earth's magnetic field is a flow of electrical charges.
• Made by the movement of hot, liquid iron and nickel in the outer core.
• Convective motion of the liquid metal, combined with the Earth's spinning, generates electric currents that create the magnetic field.
• This is known as the dynamo effect

What is the Crust?

Crust is the outermost layer of the Earth's surface. It is made of solid rocks. There are two types of crust: continental and oceanic. Continental crust: thicker and less dense

• Forming continents & shallow seas.
• On average, the older crust.

Oceanic crust: thinner and denser

• Found under the oceans.
• On average, the younger crust.

Earthquakes, volcanoes, and mountains form the crust. Minerals, fossil fuels, & water are found in the crust. The crust is composed of granite (in continental crust) & basalt (in oceanic crust).

• Earthquakes, volcanoes, and mountains are formed in the crust.

• We find important resources like minerals, fossil fuels, and water in the crust.

• The crust is broken into tectonic plates mostly composed of granite and basalt

How do Compasses Work?

• A compass is a tool that helps us find direction.

• The Earth has a magnetic field, like a giant magnet.

• The needle in the compass is magnetized and can align with the Earth's magnetic field.

• The north end of the needle points towards the Earth's magnetic south pole.

• The Earths magnetic south pole is the same as earths geographical north pole

What is the Asthenosphere?

• Below the lithosphere is the asthenosphere, which is partially melted and causes earthquakes and volcanoes.

• The asthenosphere is also responsible for tectonic plate movement due to convection currents

What is the Inner Core?

• Pressure and temperature are so high the metals cannot melt.
• Acts as a solid ball of iron and nickel.
• 3 million times the pressure you experience at sea level.
• Over 9000 degrees F. 800 mile radius (1600 mi thick).