Earth's Layers and Composition

In this Grade 9 geography lesson, Miss Cassandra Limburg explains the structure of the Earth, which consists of the core, mantle, and crust. The core is divided into the inner and outer core, with the inner core being solid and the outer core liquid. Convection currents in the core contribute to Earth's magnetic field. The mantle, made of silicate rocks, behaves as a viscous fluid over geological time and is the thickest layer. The crust, the thinnest layer, is divided into oceanic and continental types, forming the Earth's plates. The lesson concludes with a summary and homework on plate movements and boundaries.

What are the three main layers of the Earth as introduced in the lesson?

• Core, Ocean, Atmosphere

• Mantle, Crust, Ocean

• Core, Mantle, Crust

• Crust, Ocean, Atmosphere

What is the inner core primarily composed of?

• Granite

• Basalt

• Iron and nickel

• Silicate rocks

How is heat generated in the Earth's inner core?

• Through solar radiation

• By chemical reactions

• By friction between tectonic plates

• From radioactive decay of elements

What process causes the movement of liquid in the outer core?

• Evaporation

• Convection

• Condensation

• Precipitation

What is the primary composition of the Earth's mantle?

• Silicate rocks rich in iron and magnesium

• Basalt rocks

• Nickel and iron

• Granite

Which layer of the Earth is the thickest?

• Mantle

• Inner core

• Outer core

• Crust

What type of rocks primarily make up the oceanic crust?

• Limestone

• Sandstone

• Basalt

• Granite

Which crust is thicker and less dense?

• Both are the same

• Oceanic crust

• Continental crust

• Neither, they are both dense

What is the main difference between oceanic and continental crusts?

• Oceanic crust is thicker and lighter

• Continental crust is thinner and denser

• Oceanic crust is thinner and denser

• Continental crust is thinner and lighter

What is the homework assignment related to?

• Studying the atmosphere

• Discussing plate movements and boundaries

• Identifying types of rocks

• Exploring the ocean floor