- Describe two ways granite is different from basalt.
- List three common uses of igneous rocks.
- Occasionally, igneous rocks will contain both large crystals and tiny mineral crystals.
Propose a way that both these size crystals might have formed in the rock. - Why is the ocean floor more likely to have extrusive rocks than intrusive rocks?
Vocabulary
outcrop An exposure of rock that can be seen on the surface of Earth.
solidify To harden after cooling.
intrusive A type of igneous rock that forms inside the Earth.
extrusive A type of igneous rock that forms above Earth’s surface.
felsic A type of igneous rock composition that is made mostly of light minerals such as
quartz and feldspar.
mafic A type of igneous rock composition that is made mostly of dense, dark minerals like
olivine and pyroxene.
intermediate A type of igneous rock composition that is in between felsic and mafic.
ultramafic A type of igneous rock that contains more than 90% mafic minerals.
Points to Consider
- Do you think igneous rocks could form where you live?
- Would all igneous rocks with the same composition have the same name? Explain why
they might not. - Could an igneous rock cool at two different rates? What would the crystals in such a
rock look like?
4.3 Sedimentary Rocks
Lesson Objectives
- Describe how sedimentary rocks are formed.
- Describe the properties of some common sedimentary rocks.
- Relate some common uses of sedimentary rocks.