1. Rocks
Objective(s):
List and describe the three types of rocks, their properties, and how they are formed

2. 3 Categories of Rock Igneous Sedimentary Metamorphic
What determines the category a rock will be?
How it is formed

3. Igneous Rock Formation
Melting and solidification of molten rock material
Lava
Cools outside the Earth = EXTRUSIVE
Magma
Cools inside the Earth = INTRUSIVE
Lava
Magma

4. Texture CRYSTAL SIZE IN IGNEOUS ROCKS Coarse Grained = BIG CRYSTALS
Fine Grained = SMALL CRYSTALS
Glassy = NO CRYSTALS FORM

5. Coarse Grained

6. Fine Grained

7. Glassy

8. Vesicular Gas Pockets Pumice Basalt Vesicles are small holes that form
when gas escapes into the atmosphere
as the lava cools.
Pumice cools so fast gas is
Trapped inside creating many
Holes like a hard sponge

9. Cooling Rates of Igneous Rocks
The rate at which a rock from molten material cools will determine its texture
Cools Quickly = Smaller Crystals
ON EARTH’S SURFACE - Extrusive
Cools Slowly = Larger Crystals
BELOW EARTH’S SURFACE - Intrusive

10. Sedimentary Rock Formation
Most sedimentary rocks are formed by compression and cementation of sediment
SEDIMENTS =
Other pieces of other rocks and minerals

11. Sedimentary Rocks
Some sedimentary rocks are made up of particles of pre-existing rocks and minerals that were deposited by wind or water and cemented together

12. Cementation Particles are cemented together by minerals precipitated out of solution as water evaporates
Conglomerate Sandstone Siltstone
What do you notice is different about each example?
Particle size

13. Compaction or Compression
Very small sediments are compressed by the pressure of the overlying sediments, or water
Become bonded together without cement
Ex – Shale

14. Other Sedimentary Rocks
Chemical Precipitation
Minerals once dissolved in water precipitate out as a result of evaporation of seawater
Ex – Limestone, Dolostone, Gypsum, and Salt
Limestone Dolostone Gypsum Salt

15. ORGANIC Sedimentary Rocks
From something once living
Ex – Coal = Dead Plant Matter
Limestone = Shell fragments (hard
parts) of dead organisms

16. DO NOW: How are rocks classified?
Once a rock is created does it stay that way forever?

17. Metamorphic Rock Formation
Original rock form has been changed by heat and pressure
Recrystallization:
Rearrangement of crystals usually forming larger crystals
ANY ROCK can be metamorphosed to become a metamorphic rock

18. Example:
Shale  Slate  Phyllite Shist
Limestone  Marble

19. Changes of Metamorphism
New minerals form
More dense
Less porous
Distortion of rock-bending that destroys original structures
Such as fossils or pebbles

20. Foliation Thin bands or lines of aligned minerals, known as BANDING
It is caused by the re-grouping of minerals into light and dark layers within the rock
Banding is used to identify metamorphic rocks

21. Properties of Igneous Rock
1. Contain crystals (size tells how quickly the rock cooled)
2. Some appear glassy due to rapid cooling.
3. Many different colors NOT in bands.
4. No fossils

22. Properties of Sedimentary Rock
1. Composed of many sediments, some different sizes, some same size.
2. May contain fossils
3. May have distinct layers
4. Color appears dull or earthy

23. Properties of Metamorphic Rock
1. Bands of light and dark color due to foliation
2. May show signs of bending or distortion
3. Crystals are flattened, not large like igneous rock.
4. No fossils
5. No pores or openings

24. Definition and Important Facts of Geology
ROCK CYCLE
Definition and Important Facts of Geology

25. ANY ROCK TYPE CAN BE CHANGED INTO ITSELF OR ANY OTHER TYPE OF ROCK!!
Rock Cycle
The processes involved in destroying old rocks and creating new ones
REMEMBER:
ANY ROCK TYPE CAN BE CHANGED INTO ITSELF OR ANY OTHER TYPE OF ROCK!!

26. Important Facts About Geology
Nearly all rocks form from other rocks
Exceptions are Organic Rocks
Rocks are classified by how they were formed
Rock types remain stable for millions of years

27. Rock Cycle

29. Do Now
Describe how each rock type is formed