Types of Rocks

Question 1

Sedimentary rocks

Answer 1

They form from particles of other rocks or remains of plants and animals that are pressed and cemented together.

Question 2

What is clastic sedimentary rock?

Answer 2

They form from particles of rock. Examples: Shale, Sandstone, Conglomerate, and Breccia

Question 3

What are the two ways that nonclastic sedimentary rock forms?

Answer 3

They form from chemical precipitation or organic activity.

Question 4

Sediment

Answer 4

Small, solid pieces of material that come from rocks or living things

Question 5

Erosion

Answer 5

Destructive forces such as heat and cold, rain, waves, and grinding.

Question 6

Deposition

Answer 6

The process by which sediment settles out of water or wind carrying it.

Question 7

Compaction

Answer 7

The process that presses the sediment together.

Question 8

Cementation

Answer 8

While compaction is taking place, the minerals in the rock slowly dissolve.

Question 9

Uses of sedimentary rocks

Answer 9

• Limestone and sandstone cut easily into blocks for building.
• The White House is built of sandstone.
• Limestone is important for smelting ores.

Question 10

Nonclastic rocks from chemical precipitation

Answer 10

A type of sedimentary rock… Chemical rocks form when minerals that are dissolved in a solution crystallize. They can also form mineral deposits left when seas and lakes evaporate. Examples of this are halite and gypsum.

Question 11

Nonclastic rocks from organic activity

Answer 11

Sedimentary rocks that form from a once-living thing over time
Examples:
-Coal: Remains of swamp plants buried in water. The weight of the layers of plants squeeze the decaying plants.
-Limestone: Hard shells of living things produce some kinds of limestone (coral, clams, oysters, snails). When the animals die, the shells pile up as sediment on the ocean floor.
-Chalk is a type of limestone from microscopic skeletons on the ocean floor.

Question 12

What causes an igneous rock to have a fine-grained texture, and what is the texture like?

Answer 12

Caused by rapid cooling lava; these “smooth” rocks have small crystals.

Question 13

What causes an igneous rock to have a course-grained texture, and what is the texture like?

Answer 13

Caused by slow cooling magma; these “rough” rocks have large crystals.

Question 14

Porphyritic texture

Answer 14

A rock with large crystals scattered among small crystals (looks like Jell-o with chunks of fruit mixed in)… it happens when an intrusive rock cools in two stages. Large crystals form slowly, and then when the magma moves closer to the surface, small crystals form quickly.

Question 15

Grain pattern

Answer 15

Grains often form patterns. Some rocks have a grain pattern of flat layers like pancakes. Others have wavy, swirly patterns.

Question 16

What does the word igneous mean (comes from the Latin word “ignis”)?

Answer 16

Ignis means fire.

Question 17

What is an igneous rock formed from?

Answer 17

It is formed from magma or lava.

Question 18

Extrusive rock

Answer 18

Forms from lava that erupted on to the earth’s surface.

Question 19

Intrusive rock

Answer 19

Forms from magma that hardened below the earth’s surface.

Question 20

Uses of igneous rocks

Answer 20

They are hard, dense, and durable, and they have been used throughout history for tools and building materials.

• Obsidian was used by N.A.s for making very sharp tools. It looks like black glass.
• Granite has been used for building materials (statues in Ancient Egypt, fortresses by the Incas, bridges and buildings in the U.S., etc.)
• Basalt is crushed for gravel
• Pumice is abrasive (rough) and is good for cleaning and polishing. It floats on water

Question 21

Metamorphic rocks

Answer 21

They form from existing rocks that have changed their form because of heat, pressure, or ?

Question 22

What does meta mean in Greek? What does morphosis mean in Greek?

Answer 22

Meta mans change and morphosis means form.

Question 23

What can metamorphic rock form out of?

Answer 23

Sedimentary rock, igneous rock, or other metamorphic rock

Question 24

Foliated

Answer 24

means “leaf” in Latin - refers to repetitive layering in metamorphic rocks

Question 25

What does the igneous rock called granite turn into under heat and pressure?

Answer 25

The metamorphic rock called gneiss

Question 26

What does the sedimentary rock called shale turn into?

Answer 26

The metamorphic rock called slate

Question 27

What is metamorphic rock used for?

Answer 27

Marble and slate are both great materials for building. They can be used for flooring, roofing, walkways, and chalk boards.