Igneous Rocks Quiz

Why are igneous rocks also called magmatic rocks?

• Because they contain large amounts of magnetite

• Because they are formed from the consolidation of magma

• Because they are formed from sediment deposition

• Because they originate from the cooling of water

Which of the following is a major component of magma?

• Carbon dioxide

• Silicate minerals

• Sulfide minerals

• Nitrogen gas

What confines gases such as water vapor within magma?

• The presence of oxygen

• The pressure of surrounding rocks

• The high density of magma

• The cooling effect of the mantle

Where does magma originate within the Earth?

• The deep ocean floor

• The outer core

• The Earth's crust or upper mantle

• The atmosphere

Which factor contributes to magma movement towards the Earth's surface?

• Magma being denser than solid rock

• The gravitational force pulling magma downward

• The heat from the Sun

• Magma being less dense than the surrounding solid material

What provides heat for the formation of magma?

• Solar energy

• Decay of radioactive materials

• The Earth's magnetic field

• Evaporation of underground water

What happens when magma is unable to reach the Earth's surface?

• It forms sedimentary layers

• It solidifies below the surface and forms intrusive rock bodies

• It remains in a molten state permanently

• It is converted into gas and released into the atmosphere

What happens when magma reaches the Earth's surface?

• It forms extrusive rock bodies

• It forms sedimentary rocks

• It creates metamorphic rocks immediately

• It becomes part of the mantle

Which process can force magma upwards through the crust?

• Increase in atmospheric pressure

• Tectonic movements or pressure from overlying rocks

• The cooling of magma

• The movement of ocean currents

What evidence suggests that igneous rocks were once molten magma?

• They contain fossils

• They have a layered structure

• The surrounding country rocks show thermal metamorphism

• They dissolve in water over time