Term
| What do geologists observe when studying a rock sample? |
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Definition
- The rock's mineral composition
- The rock's color
- The rock's texture
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Term
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Definition
| Rocks are made of mixtures of minerals and other materials. |
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Term
| Some rock's contain a single _____________. |
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Definition
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Term
| Approximately how many minerals make up most of the rocks of Earth's crust & what are they known as? |
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Definition
| 20 & rock-forming minerals |
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Term
| What can help provide clues to the rock's mineral composition? |
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Definition
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Term
| If you test the surface of a rock with acid what will you determine? |
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Definition
| You will determine whether the rock includes minerals made of compounds called carbonates. |
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Term
| What are three things you can say about Basalt? |
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Definition
- It is a dark-colored rock.
- It has low silica content.
- Unlike granite, basalt has mineral crystals that are too small to be seen without a hand lens.
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Term
| What is granite made up o? |
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Definition
- quartz
- feldspar
- hornblende
- mica
- (It may also contain other minerals)
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Term
| Most rocks are made up of particles of minerals or other rocks, which geologists call ______________. |
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Definition
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Term
| To a geologist, a rock's _____________ is the look and feel of the rock's surface. |
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Definition
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Term
To describe a rock's texture, geologists use terms based on the:
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Definition
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Term
What is the grain size of slate?
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Definition
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Term
| What is the grain size of diorite? |
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Definition
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Term
| What is the grain size of flint? |
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Definition
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Term
| When the grains in a rock are large and easy to see, these rocks are said to be ______________. |
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Definition
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Term
| When the grains are so small that they can only be seen with a microscope they are said to be ____________. |
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Definition
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Term
| Using what three criteria can geologists classify a rock according to its origin? |
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Definition
- color
- texture
- mineral composition
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Term
| What are the three major groups geologists can classify rocks? |
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Definition
- Igneous rock
- Sedimentary rock
- Metamorphic rock
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Term
| How does the igneous rock form? |
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Definition
| from the cooling of magma or lava |
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Term
| How do most sedimentary rocks form? |
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Definition
| When the particles of other rocks or the remains of plants and animals are pressed and cemented together. |
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Term
| Sedimentary rocks are formed in ____________ and buried ________________. |
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Definition
| layers & below the surface |
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Term
| Metamorphic rock formed when and existing rock is changed by any of three things. What are they? |
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Definition
- Heat
- Pressure
- Chemical reactions
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Term
| Where do most metamorphic rock form? |
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Definition
| Most metamorphic rock forms deep underground. |
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Term
| Gneiss is a kind of rock that forms when what happens? |
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Definition
| When heat and pressure inside Earth change granite. |
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Term
| The name igneous come from what Latin word & what does it mean? |
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Definition
It comes from ignis and it means fire.
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Term
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Definition
| It is igneous rock formed from lava that erupted onto Earth's surface. |
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Term
| What is the most common extrusive rock? |
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Definition
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Term
| What forms much of the crust, including the oceanic crust, shield volcanoes & lava plateus? |
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Definition
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Term
| Igneous rock that formed when (1)_________ hardened beneath the earths surface is called (2) ___________. |
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Definition
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Term
What does the texture of an igneous rock depend on?
What are the only exceptions to this rule? |
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Definition
the size and shape of its mineral crystals
The only exception to this rule are the different types of volcanic glass - igneous rock that lacks a crystal structure. |
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Term
| Igneous rocks may be similar in mineral composition and yet have very different textures. Why? |
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Definition
| Rapidly cooling lava forms fine-gained igneous rocks with small crystals. Slowly cooling magma forms coarse-grained rocks with large crystals. |
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Term
| Why type of rock has larger crystals? Intrusive or extrusive? |
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Definition
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Term
| What is the texture of extrusive rocks like? |
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Definition
| They have a fine-grained or glassy texture. |
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Term
What type of rock is Basalt?
What size are its crystals? |
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Definition
Basalt is a fine-grained extrusive rock?
The crystals are too small to be seen wtihout a microscope. |
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Term
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Definition
| Obsidian is an extrusive rock that cooled very rapidly without forming crystals. As a result it has the smooth, shiny texture of a thick piece of glass. |
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Term
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Definition
| A fine-grained, extrusive igneous rock with a mineral composition similar to granite. |
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Term
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Definition
| A very coarse-grained intrusive igneous rock. |
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Term
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Definition
| An intrusive igneous rock with large crystals surrounded by small crystals; forms when magma cools slowly at first, then rapidly. |
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Term
| Lava that is low in silica usually forms what? |
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Definition
| It usually forms dark-colored rocks such as basalt. |
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Term
| What does basalt contain? |
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Definition
| It contains feldspar as well as certain dark-colored minerals, but does not contain quartz. |
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Term
| What does magma that is high in silica usually form? |
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Definition
| It usually forms light-colored rocks, such as granite. |
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Term
| What does granite's mineral composition determine? |
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Definition
| Its color - light gray, red, pink or nearly black |
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Term
| Granite that is light gray with drak specks is rich in what? |
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Definition
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Term
| If there are quartz crystals in granite - what does it add? |
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Definition
| light gray or smoky specks. |
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Term
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Definition
| Thin slices of a rock that geologists can make. |
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Term
| What did ancient Egyptians use for statues more than 3,500 years ago? |
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Definition
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Term
| About 600 years ago, the Incas of Peru carefully fitted together great blocks of granite and other igneous rocks to build what and where was it? |
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Definition
| They built a fortress near Cuzco, their capital city. |
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Term
| In the US during the 1800s and nearly 1900s, granite was widely used to build what? |
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Definition
Bridges
Public buildings
Paving streets with cobblestones |
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Term
| What is granite used in today? |
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Definition
Curbstones
Floors
Kitchen counters |
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Term
| What is crushed to make gravel that is used in construction? |
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Definition
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Term
| What type of rock is pumice and what is it used for? |
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Definition
It is an igneous rock.
The rough surface of pumice makes it a good abrasive for cleaning and polishing. |
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Term
| What type of rock is obsidian & what has it been used for? |
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Definition
Igneous rock.
Ancient native Americans used obsidian to make sharp tools for cutting & scraping. |
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Term
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Definition
| It's formed from the heating of obsidian and is often mixed with soild for starting vegetable seeds. |
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Term
| Describe the jagged peaks, steep cliffs and deep canyons in Badlands National Park in South Dakota. |
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Definition
| They are sculpted in colorful rock that is layered like a birthday cake. The layers of this cake are red, orange, pink, yellow or tan. |
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Term
| How were the layers in Badlands National Park formed? |
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Definition
| These rocks formed over millions of years as particles of mud, sand, and volcanic ash were depositied in thick layers. |
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Term
| Tiny sand grains, mud and pebbles along a stream or beach are what? |
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Definition
| They are particles of sediment |
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Term
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Definition
| Sediment is small, solid pieces of material that come from rocks ro living things. |
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Term
| In addition to particles of rock, sediment may include: |
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Definition
- shells
- bones
- leaves
- stems
- other remains of living things
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Term
| When do sedimentary rocks form? |
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Definition
| When sediment is deposited by water and wind |
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Term
| Most sedimentary rocks are fromed through a series of processes (4): |
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Definition
- erosion
- deposition
- compaction
- cementation
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Term
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Definition
| Destructive forces are constantly breaking up and wearing away, or weathering, all the rocks on Earth's surface. |
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Term
| What are the destructive forces causing erosion? |
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Definition
- heat & cold
- rain
- waves
- grinding ice
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