Lesson 3.2 Earth's Interior

• Explain how Geologists learn about Earth's Inner Structures

• Identify the characteristics of the different structures of the Earth

• Describe how temperature and pressure change throughout the layers of the Earth

How Do Geologists Learn about Earth's Interior?

• Processes inside the Earth often affect the Earth's Surface

• It is hard for scientists to study exactly what goes on inside the Earth

  • Geologist: A scientist who special​izes in studying the Earth, Rocks, and Minerals

    • ​Practice two methods to study inside the Earth

      • Looking at Rock Samples

      • Studying the behavior of seismic waves

Evidence from Rock Samples

• Geologists drill holes into the Earth to Collect Samples

  • Some as deep as 12.3 Kilometers ​

  • The plugs show the different layers of rocks

• Rocks also are blasted to the surface by volcanoes

• Scientists attempt to recreate the conditions inside t​he earth to test how rocks behave

  • Shoot the rocks with lasers​

Evidence from Seismic Waves

• Seismic Waves: an elastic wave in the Earth produced by an earthquake or other means

• Geologists record and study how the seismic waves ​travel throughout the Earth

  • The speed and direction can indicate how waves move around different masses​

Features of the Earth

• The Earth is made up of three main layers that vary in size, composition, temperature, and pressure

  • The Crust

  • The Mantle

  • The Core​

• Pressure: The force that presses on a certain area

  • Pressure is greater deeper inside the Earth than outside​

• The temperature inside the Earth increases as the depth increases

The Crust

• The Crust: The layer of rock that forms the Earth's outer skin

  • Solid rock that includes both dry land and the ocean floor

  • is 5-80 Km thick

• Main elements in the crust are oxygen and silicon

• Oceanic Crust: The crust beneath the ocean

  • Basalt:​ a dark fine grained rock that tends to sit on top of the oceanic crust

• Continental Crust: The crust that forms the continents

  • Contains many rocks, but mainly granite

    • Granite: A Light color rock with coarse grains

The Mantle

• The Mantle: A layer of hot rock underneath the crust

  • Extremely hot, but still solid

  • nearly 3, 000 Km thick

• Divided into layers

  • The lithosphere: a combination of the uppermost part of the mantle and lower crust (100 Km Thick)

    • Is strong and rigid

  • The Asthenosphere: much less rigid layer, but still solid

  • The Mesosphere: hotter, but more rigid and stiff

    • Contains the transition zone and the lower mantle

The Core

• The Core: The layer under the Mantle at the center of the Earth, made up mostly of the metals iron and nickel

  • Two parts

    • A liquid outer core (2,258 km thick)

    • A solid inner core (1,222 km radius)

      • Extreme pressure squeezes the atoms so much they cannot spread out to become liquid

  • May also contain oxygen, sulfur, and silicon

The Core & Earth's Magnetic Field

• ​Scientists think movements in the core create the Earth's magnetic field

  • The planet acts like a bar magnet

  • Magnets point towards the magnetic poles of the Earth, not the geographic poles​