1. Chapter 4 Rocks

2. Why must scientists who study rocks look at the inside of them?
Because the outside surfaces have been exposed to the effects of ice, water, and weather (Erosion).

3. Mineral composition and color
2. What three important things do scientists observe when studying rocks? -Mineral composition, color, and texture 3. What are rock forming minerals? -About 20 minerals that are found in the earth’s crust that make up rocks. 4. What minerals are found in granite? -Quartz, horneblende, mica, and feldspar

4. 5.Some other ways scientists study rocks include:
Shape and color of the crystals
Mineral content
Color
Texture
And some other tests similar to the tests for minerals

5. Mineral Composition: (This is also in the igneous section on page 2)
Most of Earth’s minerals contain Silica
Silica is a material formed from oxygen and silicon.
The silica content of magma and lava will affect the types of rock that form
High silica usually forms light colored rocks
Low silica usually forms dark colored rocks

6. Texture Grains- Give the rock texture What is texture?
Texture is the look and feel of the rocks surface.
The three grain sizes that make texture are:
Fine
Coarse
No visible

7. Texture: Grain Size Coarse grained = large grains and easy to see
Fine grain = microscopic and too small to see

8. There are two grain shapes:
Jagged
Round
There are two grain patterns:
Banded
Non- banded

9. There are three main groups of rocks
Igneous – forms from cooling of magma or lava
Sedimentary – forms when particles of other rocks or the remains of plants and animals are pressed and cemented together
Metamorphic – forms when an existing rock is changed by heat, pressure or chemical reactions, forms deep underground

10. Section 2: Igneous Rocks
An igneous rock is any rock that forms from magma or lava.
The name “igneous” comes from the Latin word meaning “fire”
Igneous rocks come from deep within the ground

11. Igneous Rock Identification
1. Igneous rocks are classified according to origin, texture and mineral composition
Origin
Texture
Mineral composition

12. Intrusive and Extrusive
3. Extrusive rock is formed from lava that erupted onto the earth’s surface. 4. Intrusive rock is formed when magma hardens beneath the surface. Molten rock below the earth’s surface is called magma. When it makes it to the surface it is called lava.

13. Igneous ID Questions 5-7
Texture: depends on the size and shape of the mineral crystals. The only exceptions are those rocks made of glass.
Rapidly cooling lava forms fine-grained rock
Slowly cooling lava forms coarse-grained rocks with large crystals
Intrusive rocks should have coarse-grained texture while extrusive rock will have fine-grained texture.

14. Igneous Rocks Continued Mineral Composition
1. Most of the earth’s rocks contain the mineral silica. 2. Silica content of rocks can affect the rocks color. Examples of Igneous rocks: Rhyolite, Porphyry, Pegmatite, Granite, etc.

15. Uses of Igneous Rock Building Material Cleaning and polishing
Granite
Cleaning and polishing
Pumice and obsidian
Sharp tools for cutting or scraping

16. Section 3 Sedimentary Rock
Sediment - small, solid pieces of material that come from rock or living things.
Ex. rock, shells, bones, leaves, stems, etc.
Sedimentary rocks are formed through the process of:
1.Erosion
2.Deposition
3.Compaction
4.Cementation

17. From Sediment to Rock - Sedimentary Rocks
Most sedimentary rocks are formed through a series of processes: erosion, deposition, compaction, and cementation.

18. Sedimentary Rocks *Erosion*
2. Erosion- destructive forces including heat, cold, rain, waves, grinding ice, running water, wind and ice loosen and carry it away.
(The forces of erosion form sediment)

19. Sedimentary Rocks *Deposition*
3. Deposition - the process by which sediment settles out of the water or wind carrying it

20. Sedimentary Rocks *Compaction*
4. Compaction - the process that presses sediments together
Thick layers build up over millions of years
The more layers, the more it presses down on the layers beneath them.

21. Sedimentary Rocks *Cementation*
5. Cementation - the process in which dissolved minerals crystallize and glue particles of sediment together
While compaction is occurring, the minerals slowly dissolve in the water

22. Sedimentary Rocks 6. The 3 types of sedimentary rocks are: Clastic
Organic
Chemical

23. Sedimentary Rock: Clastic
7. Clastic rock- a sedimentary rock that forms when rock fragments are squeezed together
Sediments can range in size
Ex. shale, sandstone, conglomerate, breccia

24. Sedimentary Rocks: Organic
8. Organic rock- forms where the remains of plants and animals are deposited in thick layers
Ex. coal, limestone

25. Sedimentary Rocks: Chemical
1. Chemical- when minerals that are dissolved in a solution crystallize
Ex. rock salt

26. Rocks from Reefs
1.These rocks are made from the exoskeletons of coral animals. 2. Life can only live within the first 40 meters because that is where there is enough light. 3. The exoskeletons are made from calcium. 4. A coral reef forms when the animals die and their skeletons remain building up over time. 5. Temperatures must be warm. 6.Limestone deposits can tell us that there must have been on ocean or sea there sometime in the past

28. Metamorphic Rocks
1. Heat and pressure beneath the surface of the earth can change any rock into a metamorphic rock.
2. Geologists classify metamorphic rocks according to the arrangement of the grains that make up the rocks
Foliated Rocks
Non-foliated Rocks

29. Metamorphic Rocks When a rock becomes a metamorphic rock…
Its appearance changes
Texture changes
Crystal structure changes
Mineral content changes

30. Metamorphic Rocks
3. Foliated = grains arranged in parallel layers or bands
Ex. slate, schist and gneiss

31. Metamorphic Rock
4. Non-foliated = mineral grains are arranged randomly
Ex. marble, quartzite

32. Uses of Metamorphic Rocks
5. Two of the most used metamorphic rocks
Marble – building and sculptures
Lincoln Memorial
Slate – flooring, roofing, walkways, chalkboards

33. The Rock Cycle
1. Forces deep within the Earth and at the surface, produce a slow cycle that builds, destroys, and changes the rocks in the crust.
The rock cycle is a series of processes that change rocks from one kind to another.

34. Quartz Sediment Compaction Cementation Sedimentary Rock (sandstone)
Buried Pressure
Heat
Metamorphic Rock (quartzite)
What next?

37. ROCK CYCLE ACTIVITY