Inside Our Earth Quiz

Evidence of Earth's Interior

• Geologists utilize direct evidence from rock samples and indirect evidence from seismic waves.
• Rock samples are collected through drilling, reaching depths of up to 12 km, providing insights into sub-surface conditions.
• Some rocks are ejected from depths exceeding 100 km, offering further data about Earth's interior.
• Seismic waves, generated by earthquakes, help geologists understand Earth's structure by analyzing their speed and paths.

Earth's Layers

• Earth's interior consists of three primary layers: crust, mantle, and core, each differing in size, composition, temperature, and pressure.
• The temperature increases approximately 1°C for every 40 meters descended below the Earth's surface, rising significantly as depth increases.
• Pressure also escalates with depth due to the weight of overlying rock, creating extreme conditions underground.

The Crust

• Earth's crust serves as the outer layer, composed of solid rock including land and ocean floor.
• Thickness ranges from 5 km to 100 km, making it the thinnest layer relative to the mantle and core.
• The elemental composition of the crust is predominantly oxygen (46%), silicon (28%), and aluminum (8%).

The Mantle

• Situated between the crust and core, the mantle is primarily composed of solid rock at high temperatures.
• It is approximately 2900 km thick and is divided into upper and lower sections based on physical characteristics.
• The upper mantle is partially molten and contains metals like iron and silicon, while the lower mantle remains completely molten.

The Asthenosphere

• Below the lithosphere lies the asthenosphere, characterized by increased heat and pressure, retaining solid yet malleable properties.
• The term "asthenes" means "weak," indicative of its relatively softer nature compared to surrounding mantle layers.

The Core

• Earth's core, located beneath the mantle, is primarily made of iron and nickel, consisting of an outer liquid core and a solid inner core.
• The outer core, about 2200°C and 2250 km thick, is a thick liquid under significant pressure.
• The inner core, at temperatures around 5000°C and 1200 km thick, remains a dense solid due to extreme pressures preventing atoms from becoming liquid.

Earth's Magnetic Field

• Movement within the liquid outer core generates Earth’s magnetic field, allowing the planet to behave as a giant bar magnet.

Discontinuities / Transition Zones

• Five major discontinuities mark transitions between Earth's layers:
  • Conrad Discontinuity: separates upper and lower crust.
  • Mohorovicic Discontinuity: between crust and mantle.
  • Repetti Discontinuity: between upper and lower mantle.
  • Gutenberg Discontinuity: between mantle and core.
  • Lehmann Discontinuity: between outer and inner core.

Discontinuities and Their Namesakes

• Each major discontinuity is named after a notable geoscientist, reflecting their contributions:
  • Conrad Discontinuity: Victor Conrad - American seismologist.
  • Mohorovićić Discontinuity: Andrija Mohorovićić - Croatian meteorologist and geophysicist.
  • Repetti Discontinuity: William C. Repetti - American geophysicist.
  • Gutenberg Discontinuity: Beno Gutenberg - American seismologist.
  • Lehmann Discontinuity: Inge Lehmann - Danish seismologist.