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. Classification MAFIC FELSIC Determined by the minerals they contain
Felsic and Mafic
Felsic contains lighter elements such as silica and oxygen
Mafic contains heavier elements such as iron and calcium they tend to be darker in color
MAFIC
FELSIC

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

6. Coarse Grained

7. Fine Grained

8. Glassy
Cooled too quickly
for crystals to form

9. Vesicular Gas Pockets Pumice Scoria 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

10. 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

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

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

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

14. 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

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

16. Non-Clastic 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

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

18. Top part of the table are the clastic rocks, bottom are the nonclastic
Cemented
Cemented
Cemented
Compacted
Compacted
Chemical (Precipitated)
Chemical (Precipitated)
Chemical (Precipitated)
Chemical and Organic
Organic

19. 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

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

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

22. Foliation Thin bands or lines of 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

23. 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

24. 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

25. 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

26. DO NOW: Complete the table below on your handout
Rock Type
How did it form?
Physical features
Igneous
Melting and solidification of molten rock material
Crystals
glassy
Many colors (not in bands)
No fossils
Sedimentary
compression and cementation of sediment
Sediments
May have layers
May have fossils
Dull, earthy colors
Metamorphic
changed by heat and pressure
Bands of color
May be bent or wavy
No pores/openings

27. Sample Letter
Name of Rock
This Rock is _______ A
Obsidian
Igneous B
Conglomerate
Sedimentary C
Basalt D
Slate
Metamorphic E
Sandstone F
Gneiss G
Pumice H
Schist

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

29. 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!!

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

32. Rock Cycle Animation