Igneous, Sedimentary, Metamorphic Rocks
and
The Rock Cycle
The earth is an ever-changing dynamic planet. As one investigates the various rock types
making up the earth, it is clear that rocks vary in both textural and compositional characteristics.
Earth processes continually produce new rock through volcanic activity, the breakdown,
transportation, as well as deposition of pre-existing rock, and the subjection of pre-existing rock
to varying pressures and temperatures caused by tectonic forces. These processes define the
rock cycle. Wherever one goes on the earth’s surface, the rock cycle can be observed in continual
action. If the earth’s internal processes had ceased to continue, the external processes,
exacerbated by gravity, would have long ago leveled the continents, and the resulting sediments
would have been deposited on the sea floor. In other words, the dynamics of earth would be at
rest or in a state of equilibrium. Yet, this is not the case. The rock cycle clearly demonstrates
that internal and external forces on the earth are alive and well, constantly ‘battling” each other.
The result is a state of non-equilibrium which results in an ever-changing earth surface.
Lab Objectives:
•
Determine the meaning of the rock cycle and what conditions are necessary to form
igneous, sedimentary, and metamorphic rocks.
•
Identify the names of common rock forming processes and how textural/compositional
characteristics are associated with the various geologic processes
•
Determine that the rock cycle is an open system that interacts with various other open
systems within the geosphere and how the rock cycle contributes to positive and negative
feedback mechanisms
•
Infer how specific hand samples representing all three rock groups have formed in relation
to the rock cycle
Rock Review:
In your own words, briefly explain how each rock group forms.
Igneous rocks:
Sedimentary rocks:
Metamorphic rocks:
Part A – Learning the Rock Cycle
Below is a diagram depicting the rock cycle. Complete the following:
•
Use the terms provided at the bottom of the page and fill in the various blanks to
make the rock cycle complete. On a separate piece of paper, define each term as it
relates to the rock cycle.
•
Describe the geologic environment that results in igneous, sedimentary, and
metamorphic rock types.
•
Choose three different colors (use colored pencils), and shade in the regions that
represent igneous, sedimentary, and metamorphic rock environments on the rock
cycle below.
weathering
metamorphic rocks
deposition
crystallization
sediment
transportation
sedimentary rocks
metamorphism
consolidation
igneous rocks (extrusive)
igneous rocks (intrusive)
sedimentary rock cycle
magma
melting
lithification
Part B- The Rock Cycle in Action
The diagram below demonstrates an ocean to continent plate convergent boundary where the
oceanic plate (A) is subducting beneath the continental plate (B). Complete the table below
using the rock specimens in the rock ID box, and describe each geologic environment
associated with the rock cycle in Part A.
3
5
4
A
2
1
B
Circle
number
1
2
3
4
5
Geologic
Environment
Rock
Texture
Rock’s Chemical
Composition
Rock Name
Part C
The Rock Cycle Critical Thinking Questions
1. Why is the rock cycle considered an open system?
2. Describe other earth open systems that are related to processes within the rock
cycle.
3. Where would you identify positive and negative feedback mechanisms within the
rock cycle? Does the rock cycle ever achieve equilibrium or maintain balance? Why
or why not?
4. Do you consider the rock cycle important to the existence of the human species?
Why or why not?
5. Describe three observations you have had regarding some aspect of the rock cycle.
6. Without looking at a picture of the rock cycle, draw your own rock cycle, and
include at least two rock types for each rock group.
Part D
Rock Cycle Crossword Puzzle
Across
5. compaction and cementation
6. molten rock
10. volcanic rock
12. loose, unconsolidated particles
13. evaporated or precipitated sedimentary rock
14. plutonic rock
15. light-colored igneous composition
17. a foliated metamorphic rock consisting of alternating bands of dark and light minerals
18. your instructor's name
20. the laying down of sediment
21. sedimentary rock composed of inorganic particles
23. factors that promote change in a process
Down
1. rocks produced by weathering processes
2. geologic processes that form new rock, modify rock, transport rock, and break rock down
3. phaneritic rock high in SiO2
4. rocks formed as the result of pressure and temperature
5. a sedimentary rock consisting of calcite
7. the wearing away and transport of loosened particles
8. factors that resist change within a process
9. the physical and chemical breakdown of rock
11. aphanitic rock high in Fe and Mg
16. dark-colored igneous composition
19. sedimentary rock composed of organic material
22. rocks produced by solidifying magma