1. Unit 2: Rocks Types and Their Formation
Class Notes: Mrs. Cirillo

2. Rocks: General All rocks are classified on the basis of formation
There are three categories: Igneous, Sedimentary, and Metamorphic
Minerals make up rocks
All rock info can be found in the ESRT p6,7

3. Igneous Rocks
Are classified on basis of environment of formation and mineral composition
Form by melting and solidification or crystallization of molten rock or magma/lava
Make up Earth’s crust-
oceanic-basalt
Continental-granite

4. 2 main categories: intrusive/extrusive
Plutonic
(underground)
2 main categories: intrusive/extrusive
Cooling rate determines crystal size-short cooling time=
long cooling time=
see ESRT page 6
Volcanic
(above ground)
Small or fine grained
Large or coarse grained

5. B A

6. How to use: Which minerals are found along this line (A)
Is the rock mafic or felsic?_____________
Light or dark?________
High or low density?___
Copy the percents on an index card, and measure each one
List the % of each mineral:
Potassium feldspar, quartz, plagioclase feldspar, biotite, amphibole
felsic
light
low

7. Potassium feldspar_________ Quartz___________ Biotite__________
Plagioclase feldspar___________
Amphibole_______________
20%
40% 7%
15% 5%
The percents should add up to 100%

8. Now repeat on other side as demonstrated...
If the rock is non-vesicular, coarse grained, name the rock?______________
If the rock is vesicular, noncrystalline, name the rock?_______________
Now repeat on other side as demonstrated...
granite
pumice

9. List the % for each mineral: plagioclase feldspar_________
Line B
List the % for each mineral:
plagioclase feldspar_________
biotite____________
pyroxene__________
amphibole_________
olivine__________

10. Name the rock-fine grained, extrusive (using line B)_____________
A rock is plutonic, coarse grained, and non-vesicular containing 75% olivine_____________
A rock is volcanic, fine grained, and contains 15% potassium feldspar, 42% quartz, and 30% plagioclase feldspar___________
Basalt, vesicular basalt or diabase
peridotite
Vesicular rhyolite or rhyolite

12. Sedimentary Rocks Classified upon basis of formation
Composed of WEATHERED remains of other rocks
Form by compression and compaction of sediments
(lithification)

13. Groups- Fragmental or clastic: Organic: Chemically(evaporites):
Made from pieces of broken
or weathered rock
Fragmental or clastic:
Organic:
Chemically(evaporites):
Made from the remains of plants
Or animals
Made from the
Evaporation of sea
Water, or as chemical
Precipitates in
Sea water

14. Will find fossils remains in these rocks!!!

16. See page 6 ESRT:
Relationship of transported Particle Size to Water Velocity….
How is this table used in conjunction with the sedimentary rock table???

17. See page 7 ESRT: Scheme for Sedimentary Rock ID
Classify Shale:
Classify Limestone:
Inorganic land derived sedimentary
Rock consisting of clay particles
Chemically or organically formed
Crystalline or bioclastic rock consisting
Of calcite

18. Name the rock: a clastic, fine grained (0.006cm) rock____________
Name the rock: a bioclastic, coarse grained rock that reacts with HCL___________________________
siltstone
limestone

19. 18. What type of relationship is shown on the graph?
16. How fast does a stream have to be traveling to transport a sediment 0.2cm, and what type of sediment is this?
17. How fast does a stream have to be traveling to transport a 27cm boulder?
18. What type of relationship is shown on the graph?
19. What process is this?
20. Can you infer how this may relate to producing various types of rock?
10cm/s
200cm/s
Direct
EROSION
As the stream deposits sediments the different sedimentary rocks form

20. What is the map symbol for rock salt?
Why do you think they choose that symbol?
Because Halite has cubic shaped crystals

21. Metamorphic Rocks Igneous
Form when sedimentary or igneous rocks undergo intense heat and/or pressure
Have undergone significant changes deep within the earth
Forms directly from another rock!!!
Never melts (if melts what type of rock would it be?_________________)
Igneous

22. Classified on the basis of formation Types of metamorphism:
Regional:
Contact:
Form by heat and/or pressure
During mountain building processes
Or continental collisions
Form by direct contact with molten rock
(lava or magma)

23. Alignment or segregation of minerals
In metamorphic rock, producing a
Layered appearance
Foliation:
Banding:
Distortion:
Type of layering or foliation found in
Some metamorphic rocks that is
Caused by movement or growth
Of minerals into homogenous layers
Warping or bending of some
Types of metamorphic rocks
That occurs with intense
pressure

24. Would you find fossils in this rock type?NO

25. Lets start with shale….
Shale slate
Rhyolite schist
Granite gneiss

26. Let’s look at the diagram below: Relate the depth to heat and pressure and the ESRT

28. Using page 7, Scheme for Metamorphic Rock ID answer…
Non foliated fine to coarse
Regionally formed
Metamorphism of sandstone
Classify Quartzite:
2. Classify Marble:
3. Which rock is the result of intense metamorphism?
4. Give an example of a fine grained foliated rock?
Metamorphism of limestone
Non foliated, contains calcite
GNEISS
slate