Sedimentary and Igneous Rocks

How do igneous rocks form?

• When sediments like sand are compacted and cemented together.

• When lava or magma cools and solidifies.

• When water evaporates and minerals form crystals.

What is the difference between intrusive and extrusive igneous rock?

• Intrusive igneous rocks cools slowly inside earth and have large crystals.

• Intrusive igneous rocks cool rapidly above Earth's surface and have small crystals.

• Extrusive igneous rocks cools slowly inside earth and have large crystals.

What is the main difference between mafic and felsic igneous rocks?

• Felsic igneous rock are low in iron and light in color. They come from melted crust.

• Felsic igneous rocks are high in iron and dark in color. They come from melted mantle.

• Mafic igneous rock are low in iron and light in color. They come from melted crust.

This is Yosemite National Park's famous half dome, a huge outcrop of granite. Granite is usually light in color and has visible crystals. Which of the following describes granite?

• Granite is intrusive, mafic igneous rock.

• Granite is intrusive, felsic igneous rock.

• Granite is extrusive, mafic igneous rock.

Answer explanation

It is intrusive because it has large crystals and granitic because it is light in color.

This is a sample of gabbro. Gabbro is dark in color, dense, and has visible crystals. Which of the following describes gabbro?

• Gabbro is felsic and intrusive.

• Gabbro is mafic and intrusive.

• Gabbro is felsic and extrusive.

Answer explanation

It is basaltic because of its dark color and intrusive because it has visible crystals.

Sedimentary rocks made of pieces of sediment compacted and cemented together are called...

• clastic sedimentary rocks

• chemical sedimentary rocks

• organic sedimentary rocks.

Sedimentary rocks that form when minerals in water form crystals are called...

• clastic sedimentary rocks

• chemical sedimentary rocks

• organic sedimentary rocks

Sedimentary rocks that form from things that were once alive are called...

• clastic sedimentary rocks.

• chemical sedimentary rocks.

• organic sedimentary rocks.

What TWO processes help form sedimentary rock from sediment?

• cooling

• melting

• compaction

• cementation

Pumice forms when very gassy magma that is low in iron erupts and cools very quickly. Pumice is a(n)...

• chemical sedimentary rock.

• mafic igneous rock.

• organic sedimentary rock.

• felsic igneous rock.