Properties and Formation of Igneous Rocks

The video tutorial explains igneous rocks, one of the three major rock types, formed from cooling magma or lava. It distinguishes between magma (below Earth's surface) and lava (above Earth's surface), and describes how crystal structures form as they cool. The video covers two classifications of igneous rocks: intrusive (cool slowly underground) and extrusive (cool quickly above ground). It discusses how cooling rates affect crystal size and the role of crystal formation in radiometric dating. Unique igneous rocks like pumice and obsidian are highlighted, with pumice forming from foamy lava and obsidian from rapid cooling.

What is the primary difference between magma and lava?

• Magma is cooler than lava.

• Magma and lava are the same.

• Magma is found below the Earth's surface, while lava is above.

• Magma is found above the Earth's surface, while lava is below.

How do intrusive igneous rocks form?

• They are formed by metamorphic processes.

• They form from sedimentary processes.

• They cool slowly below ground.

• They cool quickly above ground.

What is a characteristic of extrusive igneous rocks?

• They cool quickly above ground.

• They cool slowly.

• They form below the Earth's surface.

• They have large crystals.

Why do intrusive rocks have larger crystals?

• They cool quickly, allowing crystals to grow.

• They cool slowly, allowing crystals to grow over time.

• They are formed from lava.

• They are formed from sedimentary processes.

What happens to crystal size as lava cools faster?

• Crystals do not form.

• Crystals become larger.

• Crystals remain the same size.

• Crystals become smaller.

How does crystal formation relate to radiometric dating?

• It starts the countdown for dating once crystals solidify.

• It speeds up the dating process.

• It has no relation.

• It ends the countdown for dating once crystals solidify.

What is a unique property of pumice?

• It forms from slow cooling magma.

• It is a type of sedimentary rock.

• It can float on water.

• It is denser than water.

How does obsidian form?

• Through slow cooling of magma.

• Through sedimentary processes.

• Through metamorphic processes.

• Through super fast cooling of lava.

What is a characteristic of obsidian?

• It is porous and floats on water.

• It is a glassy black rock.

• It has large crystals.

• It forms from slow cooling magma.

Which of the following is true about pumice?

• It is denser than water.

• It is a type of metamorphic rock.

• It forms from slow cooling magma.

• It has small air pockets.