2
Earth Materials and Processes
Learning Objectives
After reading and studying this chapter, students should be prepared to discuss:
* The geologic cycle and its sub-cycles (tectonic, rock, hydrologic, and biogeochemical).
* Some of the important mineral and rock types and their environmental significance.
* Rock structures such as fractures and folds.
* Landforms, deposits, and environmental problems resulting from wind and glacial processes.
Chapter Summary
This chapter focuses on geologic and surficial processes, as well as rocks and minerals. It opens with a
section on the tectonic and rock cycles and their interrelationships, the hydrologic cycle, and
biogeochemical cycles. The chapter then turns to a discussion on the various types of rocks (with a brief
section on minerals), as well as rock strength, structures, and laws. The chapter closes with a section on
surficial processes, particularly ice and wind processes.
Chapter Outline
I. The geologic cycle
A. The tectonic cycle
1. A closer look: The wonder of mountains
B. The rock cycle
C. The rock cycle and the tectonic cycle
D. The hydrologic cycle
E. Biogeochemical
II. Rocks
A. A closer look: Minerals
B. The strength of rocks
1. Putting some numbers on: Stress, strain, and strength of rocks
C. Types of rocks
D. Three rock laws
E. Rock structures
F. Case history: St. Francis dam
III. Surficial processes
A. Ice
B. Wind
Some Questions to Think About
1. An answer to this question would have to consider a comprehensive look at how the physical
characteristics of an Earth dominated by one continent and one ocean might differ, and how those
physical characteristics would affect climate, rock weathering, and other processes might differ. In
particular, the answer will need to consider how the lack of younger mountain ranges might affect
these processes.
2. The student will need to consider the likely changes in the carbon cycle that would result from a
doubling of fossil carbon output, accounting for the proportions that are transferred to ocean and land
and how those proportions might change.
3. In particular, the student will need to determine the impacts of life on rock weathering and how those
impacts affect the types of rocks as well as the parts of the rock cycle affected and not affected.
4. The steps the student will propose to stabilize the dunes will rely on knowledge of wind erosion and
transportation processes, and how those processes can be altered to slow the migration of the dunes.
5. An answer to this question should include a satellite-based program to monitor glacier area and
volume, which would need to be sensitive enough to determine changes in glaciers and ice sheets. The
linkage to sea- level rise would hinge on calculation of the volume of ice loss or gain and a method to
determine the amount of sea-level change that would result.
Exam Questions
Multiple Choice
1. The supercontinent that began to break up through tectonic processes about 200 million years ago is
called
a. Pangaea
b. Gondwana
c. Asia
d. Laurasia
Answer: a
Difficulty Level: 1
Section Number: 2.1
Bloom’s taxonomy level: Remembering
2. Why are silicate minerals the most common minerals in the crust?
a. because oxygen and silicon are the most common elements in the crust
b. because carbonate and oxide minerals are more easily weathered
c. because their building block is in the shape of a tetrahedron
d. because they include elements such as magnesium, sodium, and potassium
Answer: a
Difficulty Level: 2
Section Number: 2.2
Bloom’s taxonomy level: Understanding
3. Sulfide minerals are potential environmental hazards because
a. they are weak minerals
b. they are rich in calcium, which contributes to water degradation
c. they can combine with oxygen and water to form sulfuric acid
d. they are important sources of iron
Answer: c
Difficulty Level: 2
Section Number: 2.2
Bloom’s taxonomy level: Understanding
4. In what way is the rock cycle intertwined with plate tectonics?
a. plate tectonic processes control the rock-forming processes prevalent at plate boundaries
b. plate tectonic processes are directly responsible for weathering
c. plate tectonic processes are responsible for the internal heat that causes metamorphism and melting
d. plate tectonic processes are directly responsible for sediment deposition
Answer: a
Difficulty Level: 3
Section Number: 2.1
Bloom’s taxonomy level: Understanding
5. An unconformity represents
a. a gap in the geologic record
b. a time when the rock sequence was below sea level
c. a period of igneous intrusion
d. an example of the principle of superposition
Answer: a
Difficulty Level: 1
Section Number: 2.2
Bloom’s taxonomy level: Understanding
6. Detrital sedimentary rocks differ from chemical sedimentary rocks in that
a. detrital sedimentary rocks accumulate in depositional basins, while chemical sedimentary rocks do not
b. detrital sedimentary rocks are composed of visible pieces of preexisting rocks
c. chemical sedimentary rocks are composed of chemical elements, while detrital rocks are not
d. chemical sedimentary rocks accumulate in the ocean, while detrital rocks do not
Answer: b
Difficulty Level: 3
Section Number: 2.2
Bloom’s taxonomy level: Remembering
7. Some metamorphic rocks are potential environmental hazards because
a. foliation can represent a plane of weakness in the rock
b. the fluids that metamorphose the rocks can leave behind dangerous chemicals
c. they are composed of unstable elements
d. the crystals do not interlock as in igneous rocks
Answer: a
Difficulty Level: 2
Section Number: 2.2
Bloom’s taxonomy level: Understanding
8. Plastic deformation results in
a. a return to the original shape of the rock once the pressure is released
b. fractures, such as joints and faults
c. permanent change in the shape of the rocks
d. increased rock temperature and, thus, increased metamorphism
Answer: c
Difficulty Level: 2
Section Number: 2.2
Bloom’s taxonomy level: Understanding
9. Joints differ from faults primarily
a. with respect to the types of deformation that form them
b. whether displacement has occurred
c. with respect to strength of the rocks
d. the amount of weathering to which they are prone
Answer: b
Difficulty Level: 2
Section Number: 2.2
Bloom’s taxonomy level: Understanding
10. A glacier of continental scale is called
a. an ice sheet
b. a valley glacier
c. permafrost
d. a surging glacier
Answer: a
Difficulty Level: 1
Section Number: 2.3
Bloom’s taxonomy level: Remembering
Fill-in-the-Blank
1. _____________ is a hard mineral that is one of the most abundant minerals in the Earth’s crust.
Answer: Quartz
Difficulty Level: 1
Section Number: 2.2
Bloom’s taxonomy level: Remembering
2. Limestone may cause construction problems because it is prone to the process of __________.
Answer: dissolution
Difficulty Level: 2
Section Number: 2.2
Bloom’s taxonomy level: Understanding
3. The carbon cycle is an example of a __________ ______.
Answer: biogeochemical cycle
Difficulty Level: 2
Section Number: 2.1
Bloom’s taxonomy level: Remembering
4. ___________ sedimentary rocks are formed from the precipitation of substances dissolved in water.
Answer: Chemical
Difficulty Level: 1
Section Number: 2.2
Bloom’s taxonomy level: Understanding
5. _______________ is a metamorphic rock, originating as shale or basalt, with many important uses.
Answer: Slate
Difficulty Level: 2
Section Number: 2.2
Bloom’s taxonomy level: Remembering
6. ________________ deformation is recoverable.
Answer: Elastic
Difficulty Level: 2
Section Number: 2.2
Bloom’s taxonomy level: Understanding
7. A ____________ is an unconformity between parallel layers of sediment.
Answer: disconformity
Difficulty Level: 2
Section Number: 2.2
Bloom’s taxonomy level: Understanding
8. A plate tectonic boundary in which plates move together is called a ________________ boundary.
Answer: convergent
Difficulty Level: 3
Section Number: 2.1
Bloom’s taxonomy level: Understanding
9. The law of _____________ _______________ states that sedimentary rocks accumulate in an un-tilted
geometry.
Answer: original horizontality
Difficulty Level: 3
Section Number: 2.2
Bloom’s taxonomy level: Understanding
10. A deposit of wind-blown silt or dust is called __________.
Answer: loess
Difficulty Level: 3
Section Number: 2.3
Bloom’s taxonomy level: Remembering
Essay
1. Describe how tectonic activity, climate, and Earth surface processes combine to influence
mountain ranges.
2. The breakup of Pangaea was a major event in Earth history. Describe how the breakup of
Pangaea affected the Earth’s topography, ocean circulation, and climate.
3. Discuss the ways in which the rock cycle and the hydrologic cycle influence the carbon cycle.
4. Rock deformation takes multiple forms. Discuss how elastic, plastic, and brittle deformation
influence development of folds, faults, and earthquakes.
5. Discuss at least three ways in which ice and wind influence the rock cycle and mountain
building processes.