Types of Igneous Rock and the Rock Cycle

Questions and Answers

What is the primary distinguishing feature of intrusive igneous rocks?

They form from lava that cools rapidly on the surface.

They are generally wholly crystalline with large crystal sizes. (correct)

They are formed by sediment compacting under heat and pressure.

They have low silica content and are typically light-colored.

What characterizes felsic igneous rocks?

They are dark-colored and high in density.

They form as a result of pressure and temperature changes in sedimentary rocks.

They contain over 90% mafic minerals.

They are high in silica and tend to be light-colored. (correct)

Which statement describes extrusive igneous rocks accurately?

They mainly consist of calcic plagioclase and quartz.

They solidify beneath the Earth's surface and are called plutonic.

They crystallize slowly and are characterized by small crystal sizes.

They form when magma erupts and cools at or near the Earth's surface. (correct)

What happens to sedimentary rock when subjected to heat and pressure?

It transforms into metamorphic rock. Signup and view all the answers

Which type of igneous rock is characterized by having a low density?

Felsic rocks Signup and view all the answers

How are ultramafic rocks classified?

They contain more than 90% mafic minerals. Signup and view all the answers

What is the role of silica content in classifying igneous rocks?

It influences the color and density of the rocks. Signup and view all the answers

What type of minerals primarily make up intermediate igneous rocks?

A mixture of mafic and felsic minerals. Signup and view all the answers

Study Notes

Types of Rock

Three main rock types: Igneous, Sedimentary, Metamorphic.
Rock Cycle involves the transformation between these rock types driven by geological processes.

Igneous Rock Formation

Formed from the cooling and solidification of magma (beneath Earth's surface) or lava (upon eruption).
Eruptions produce lava, while magma remains as molten rock underground.

Types of Igneous Rock

Intrusive Igneous Rocks (Plutonic Rocks):
- Solidify within the Earth.
- Characterized by large crystal sizes, visible to the naked eye, due to slow cooling.
Extrusive Igneous Rocks (Volcanic Rocks):
- Formed when magma exits and cools quickly on or near Earth's surface.
- Associated with erupting volcanoes and fissures.

Classification by Silica Content

Felsic Rocks:
- High in silica, including feldspar and quartz.
- Tend to be light-colored and have low density.
Mafic Rocks:
- Low in silica, composed of calcic plagioclase, olivines, and pyroxenes.
Intermediate Rocks:
- Moderate silica content, primarily composed of feldspar.
- Typically have a density between felsic and mafic.
Ultramafic Rocks:
- Very low in silica, composed of over 90% mafic minerals.
- Often dark-colored with high density.

Description

This quiz focuses on igneous rocks and their role in the rock cycle. You'll explore how igneous, sedimentary, and metamorphic rocks transform and interact with one another. Test your knowledge of rock types and the processes that lead to their formation.