Extrusion

The video explains how magma cools quickly in extrusive rocks, preventing large crystal formation, resulting in small mineral grains. Basalt is highlighted as the most common type of extrusive rock.

What are the two ways magma can cool to form rocks?

• By mixing with water

• In steady flows or violent eruptions

• By exposure to sunlight

• Through slow underground processes

Why do rocks formed above ground have smaller mineral grains?

• Because magma cools faster above ground

• Because they are exposed to air

• Because they are formed in water

• Because they are older

What is the main reason large crystals do not form in extrusive rocks?

• Rapid cooling of magma

• Lack of pressure

• High temperatures

• Presence of impurities

Which type of rock is most commonly formed from extrusive processes?

• Marble

• Basalt

• Granite

• Limestone

What characteristic is typical of extrusive rocks due to their formation process?

• Small mineral grains

• High density

• Large mineral grains

• Bright colors