EOY Bellwork 3: Earth's Layers and Tectonics

Which layer of the Earth is composed of solid rock and forms the thin outermost shell?

• Mantle

• Crust

• Outer Core

• Inner Core

Answer explanation

The crust is the Earth's outermost layer, composed of solid rock. It forms a thin shell over the mantle, distinguishing it from the liquid outer core and solid inner core.

What is the main composition of the Earth's core?

• Silica and magnesium

• Iron and nickel

• Oxygen and nitrogen

• Carbon and hydrogen

Answer explanation

The Earth's core is primarily composed of iron and nickel, which are dense metals. This composition is crucial for generating the planet's magnetic field and contributes to its overall structure.

Which type of plate boundary is most likely to create new oceanic crust?

• Convergent boundary

• Divergent boundary

• Transform boundary

• Subduction zone

Answer explanation

A divergent boundary occurs when tectonic plates move apart, allowing magma to rise and solidify, creating new oceanic crust. This process is responsible for the formation of mid-ocean ridges.

What process in the mantle is responsible for the movement of tectonic plates?

• Radiation

• Convection currents

• Conduction

• Evaporation

Answer explanation

Convection currents in the mantle create movement due to the heat from the Earth's core. These currents cause the tectonic plates to shift, leading to geological activity such as earthquakes and volcanic eruptions.

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Which geological feature is most commonly formed at convergent boundaries?

• Mid-ocean ridges

• Mountains

• Rift valleys

• Ocean trenches

Answer explanation

Mountains are commonly formed at convergent boundaries due to the collision of tectonic plates, which causes the Earth's crust to fold and uplift. This process leads to the creation of mountain ranges.

Which of the following best describes the theory of plate tectonics?

• The Earth is a solid, unmoving sphere.

• The Earth's surface is made up of plates that move and interact.

• The Earth's core is the only moving part.

• The continents are fixed and do not move.

Answer explanation

The theory of plate tectonics states that the Earth's surface is divided into plates that move and interact with each other, causing geological activity. This is contrary to the idea of a solid, unmoving sphere or fixed continents.

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Which type of plate boundary is most likely to cause earthquakes due to plates sliding past each other?

• Convergent boundary

• Divergent boundary

• Transform boundary

• Subduction boundary

Answer explanation

The transform boundary is where tectonic plates slide past each other horizontally. This movement can cause significant stress and lead to earthquakes, making it the correct choice for this question.

Compare the properties of the Earth's crust, mantle, and core.

• All are liquid layers.

• Crust is solid rock, mantle is semi-solid, core has both liquid and solid parts.

• Crust and core are both liquid, mantle is solid.

• All are made of iron and nickel.

Answer explanation

The correct choice states that the crust is solid rock, the mantle is semi-solid, and the core has both liquid and solid parts. This accurately reflects the composition and state of each layer of the Earth.

Why are volcanoes commonly found at both convergent and divergent boundaries?

• Because plates are stable there.

• Because magma can reach the surface when plates move apart or collide.

• Because the crust is thickest there.

• Because there is no tectonic activity.

Answer explanation

Volcanoes are found at convergent and divergent boundaries because these tectonic plate movements allow magma to rise to the surface. At divergent boundaries, plates pull apart, while at convergent boundaries, they collide, both facilitating volcanic activity.

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A scientist discovers similar rock formations and fossils on the coasts of South America and Africa. What conclusion can be drawn, and what evidence supports it?

• The continents have always been separate; ocean currents moved the fossils.

• The continents were once joined as Pangea; similar fossils and rocks are evidence.

• The continents are moving closer together.

• The fossils are not related.

Answer explanation

The discovery of similar rock formations and fossils on South America and Africa supports the conclusion that these continents were once joined as Pangea. The matching geological features and fossils provide strong evidence of this ancient connection.

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