Earth's Layers Quiz

Earth's Layers

• Earth has several layers with distinct properties.
• The lithosphere is the uppermost solid layer, comprising the crust and upper mantle.
• The lithosphere extends from the surface to 50-280 km below.
• It's mainly composed of rocks, minerals, and solid ground.

Crust

• The crust is Earth's outermost, thin layer (5-70 km thick).
• It accounts for only 1% of Earth's mass.
• Two types exist: oceanic (thin, dense) and continental (thick, less dense).

Mantle

• The mantle is a thick layer (2,900 km) making up 85% of Earth's volume.
• Divided into upper and lower mantle.
• The upper mantle (asthenosphere) is semi-molten rock flowing in convection currents.
• The mantle is dense, iron-rich, and hotter than the crust.

Core

• The core is the innermost layer, located 2,900 km below the surface.
• Composed of an outer and inner core.
• Mostly iron and nickel, with the inner core being solid due to immense pressure.
• The center of Earth is approximately 6,500 km from the surface.

Plate Tectonics

• The lithosphere is divided into rigid plates.
• Plates float/rest on the asthenosphere.
• Plate movement is driven by convection currents within the mantle.
• Plates can collide, slide past, or separate.

Studying Earth's Interior

• Seismologists use seismic waves (P-waves & S-waves) from earthquakes to study the inner structure.
• P-waves travel through solids and liquids; S-waves only travel through solids.
• The behavior of seismic waves helps determine the composition and state of each layer.
• Scientists also drill into the crust to study its structure.

Minerals

• A mineral is a naturally occurring, crystalline solid with a defined chemical composition.
• Minerals have a regular internal crystalline structure.
• Key physical properties include luster, hardness, cleavage, fracture, magnetism, density, and acid reaction.
• Water is not a mineral as it's liquid, unlike solid minerals.