Structure of the Earth

Structure of the Earth

• The Earth is composed of several layers: Crust, Mantle, Core, and Atmosphere.

Learning Objectives

• Recall and describe the structure of the Earth (D Grade).
• Describe the relative sizes of each layer (C Grade).
• Explain where minerals and resources are found (B Grade).
• Discuss developing ideas about the Earth's structure (B Grade).

Key Terms

• Crust: Thin outer layer, consists of granitic and mafic silicates.
• Mantle: Composed primarily of ultramafic silicates.
• Core: Made mostly of iron, nickel, and sulfur.
• Atmosphere: A layer of gases surrounding Earth.

Structure Breakdown

• Crust: Thinnest layer.
  • 3 to 5 miles (8 km) thick under oceans; up to 25 miles (32 km) thick under continents.
  • Contains minerals and other essential resources.
• Mantle:
  • Width of approximately 1,800 miles (2,885 km).
  • Behaves like a solid but flows slowly, with the upper mantle having a semi-solid aspect due to convection currents.
• Core:
  • Radius of about 3,500 km, consists of liquid outer core and solid inner core.
  • Outer core is liquid; inner core is rigid and very hot.

Resource Availability

• Earth provides natural materials and resources from the crust, oceans, and atmosphere.
• Importance of conservation for future generations due to limited resource supply.

Tectonic Plates

• Tectonic plates are large pieces of the Earth’s crust that move, impacting geological processes.
• Plates have boundaries that are categorized as Divergent, Convergent, and Lateral Sliding:
  • Divergent: Plates move apart, creating new crust (constructive).
  • Convergent: Plates move towards each other, potentially causing subduction (destructive).
  • Lateral Sliding: Plates slide past one another with no crust created or destroyed (conservative).

Earthquakes

• Seismic waves generated by earthquakes provide insights into the structure of the Earth based on their speed and travel paths through different layers.
• The study of these waves helps scientists learn more about Earth's internal structure.

Developing Understanding

• Importance of discussions and collaborative learning to reinforce knowledge about the Earth’s structure.
• Reflection through exercises and plenary discussions to solidify understanding of material covered.