Download StudyQuestions2

Geology 101 - Earth & Environment - Fall 2016
Study Questions set 2
Major themes:
Earth materials and processes; Material properties, atomic structure, and composition;
Scientific classification; Observation and testing; Rocks as the book of Earth history.
Part 1 - Minerals
1. What is scientific classification? What is it used for? Why is it useful?
2. What is a mineral? What criteria must a substance meet to be classified as a mineral?
(theme: scientific classification)
3. Is water a mineral? Is coal a mineral? Is ice a mineral? Is glass a mineral? Explain why
or why not for each.
4. Describe at least three ways in which minerals are important to your life and to the
larger economy.
5. What are some of the possible colors of quartz (include at least four)? Why is mineral
color not a very reliable property for identifying minerals like quartz?
6. What is streak? Do all minerals have a colored streak? Explain.
7. What is luster? How can you tell the difference between metallic and non-metallic
lusters? List some minerals that have a metallic luster.
8. How are cleavage and fracture different? Do all minerals have cleavage? How can you
determine if a mineral sample has cleavage?
9. What test can you perform to determine the hardness of a mineral? Using Moh's scale,
describe the hardness of talc, quartz, and diamond.
10. What is density? What two measurements are needed to calculate the density of a
mineral?
11. For what common mineral is the "acid test" important? What common mineral tastes
salty?
12. Explain how ionic bonding and covalent bonding work. What part of the atom is
involved in both. How are these two types of bonding different?
13. What type of weak bonding holds together the atomic layers in graphite?
14. Explain how composition (i.e. what elements) and structure (i.e. arrangement and
bonding) determine the properties of minerals. Be sure to include the following:
a What makes some minerals harder than others? Explain using graphite and diamond as
examples.
b Why do some minerals have very good cleavage but others do not? Use the single
direction of cleavage in graphite as an example.
c Why is galena more dense than halite?
d Why do galena and halite have the same crystal shape and same cleavage pattern?
15. Summarize the way minerals are classified into groups by composition:
a What do all oxide minerals have in common? List two examples, including mineral
names and chemical formulas.
b What do all carbonate minerals have in common? List two examples, including
mineral names and chemical formulas.
c What do all sulfide minerals have in common? List two examples, including mineral
names and chemical formulas.
d What is a native element mineral? List two examples, including mineral names and
chemical formulas.
16. What are silicate minerals? What is the basic building block or structural unit of all
silicate minerals? What is this basic unit composed of?
17. Explain why silicate minerals are the most common type of minerals in the Earth's
crust. (Hint: Think back to differentiation in the first set of lecture slides.)
Part 2 – Introduction to Rocks; Igneous Processes and Igneous Rocks
1. How is a mineral different from an element? How is a rock different from a mineral?
Put minerals, rocks, and elements in order from simplest to most complex.
2. What are the eight most common or “rock-forming” minerals? Why are they called
this? Why are they all silicates?
3. How are igneous rocks formed? What major processes are involved?
4. Where are intrusive (plutonic) and extrusive (volcanic) igneous rocks formed?
5 How is magma different from lava? How are magma and lava the same?
6. What are dikes and batholiths, and how are they formed?
7. How are the compositions of felsic and mafic rocks different? List three different ways
by which felsic and mafic rocks can be distinguished from each other.
8. How are intermediate composition rocks different from felsic and mafic rocks?
9. What are phaneritic, aphanitic, glassy, and porphyritic textures? Describe the pattern of
cooling that produces each of these textures.
10. How is the rate of cooling related to where molten rock cools and solidifies? How can
you tell if a rock is intrusive or extrusive in origin?
11. What is a vesicular texture? How does it form?
12. What is a fragmental texture? How does it form? List three examples of igneous rocks
that have a fragmental texture.
13. Explain how igneous rocks are classified. Classify each of the following examples:
• An intrusive igneous rock that is felsic in composition is classified as _________
• An extrusive igneous rock that is intermediate in composition is classified as
_________
• An extrusive igneous rock that is mafic in composition is classified as _________
• A felsic igneous rock that is mostly composed of bubbles is classified as _________
• A volcanic rock made up of volcanic ash, pumice, and other rock fragments stuck
together is classified as _________
14. What minerals could you expect to find in a granite? What igneous rocks could
contain olivine?
15. Places that sell building stones and stone tiles sometimes sell a rock called “black
granite.” This rock isn’t really granite, but it has a coarse texture like granite. Use the
coarse texture and dark color to determine the proper classification of “black granite.”
16. In what three ways can rocks be made to melt and form magma? Which of these is
most important for melting at ocean ridges and hot spots? Which of these is most
important for melting at subduction zones?
17. Describe at least three processes that can change the chemical composition of a
magma after its initial formation.
Part 3 - Sedimentation and Sedimentary Rocks
1. How are sedimentary rocks different from igneous rocks?
2. Why are sedimentary rocks important? What can they be used for?
3. What is chemical sediment? How is it formed? Include two examples.
4. What is clastic sediment? How is it formed? Include two examples.
5. What is biochemical sediment? How is it formed? Include two examples.
6. How does sediment transport affect grain size, grain shape, and sorting? Consider the
effect of transport distance, and consider different transporting agents (i.e. water, wind,
and ice).
7. What is a sedimentary depositional environment? What are the three major categories
of depositional environments.
8. Consider the relationship between the depositional environment and the type of
sediment that accumulates there: In what specific environments can mud be
deposited? In what environment(s) can gravel be deposited? In what environment(s) can
salt accumulate? Why does each type of sediment accumulate in each of these
environments?
9. How is cement important for forming sedimentary rocks? What are the two most
common types of cement in sedimentary rocks?
10. What are sedimentary structures? What do mud cracks, ripples, and cross-bedding
found in sedimentary rocks tell us about the past?
11. Explain how clastic sedimentary rocks are classified. Classify each of the following
examples:
a A rock containing lots of rounded pebbles is classified as ______
b A rock containing a mixture of angular pebbles and sand classified as ______
c A rock composed of quartz sand is classified as ______
d A rock composed of sand containing a mixture of quartz, feldspar, and mica is
classified as ______
e A rock composed of fine sediment like mud is classified as ______
12. Explain how chemical and biochemical sedimentary rocks are classified. Be sure to
include the following examples:
a A rock that is composed of calcite and which contains abundant fossil shells is
classified as ______
b A rock that is composed of the mineral halite is classified as ______
a
13. How do sedimentary rocks help us to learn about the past history of the Earth? What
does finding a deposit consisting of layers of sandstone alternating with layers of
conglomerate tell us about what happened? What does finding a deposit of limestone
with fossil shells tell us about what happened? What does finding the limestone above
the sandstone/conglomerate in the same cliff tell us about the geologic history?
Part 4 - Metamorphism and Metamorphic Rocks
1. What is metamorphism? What types of changes can happen during metamorphism?
2. How are temperature, pressure, and fluids important in causing metamorphism? What
can fluids do to the rock that heat and pressure cannot?
3. What is regional metamorphism? What are the two major types of regional
metamorphism? Where does regional metamorphism occur? Put the locations where
regional metamorphism occurs in the context of plate tectonics.
4. Describe how contact metamorphism occurs. Which cause(s) of metamorphism is/are
most important for contact metamorphism? Where does contact metamorphism occur?
Put the locations where contact metamorphism occurs in the context of plate tectonics.
5. Which affects more rocks - regional metamorphism or contact metamorphism?
Explain.
6. What is foliation? How can you tell if a rock is foliated?
7. How is foliation in metamorphic rocks formed? What type of pressure is required to
produce foliation? What type of metamorphism produces foliated rocks?
8. Explain how foliated metamorphic rocks are classified. Explain the differences
between slate, phyllite, schist, and gneiss.
9. Explain how non-foliated metamorphic rocks classified. Explain the key difference
between quartzite and marble.
10. What is meant by the term "parent rock" or protolith? How is the parent rock
important to the results of metamorphism? What is the parent rock of marble? What is the
parent rock of quartzite?
11. What is metamorphic grade? What is the difference between high and low grade?
What is the metamorphic grade of gneiss? What is the metamorphic grade of slate?
12. How does the grade of metamorphism vary with distance from an igneous intrusion?
Part 5 - Summarizing Rock-Forming Processes and How the Earth Recycles: The
Rock Cycle
1. What is the rock cycle? Why is it called the rock cycle? What processes are part of the
rock cycle? Draw a sketch illustrating the rock cycle with all of the processes and
possible pathways included.
2. Using the rock cycle, describe how a metamorphic rock can be made into an igneous
rock. Describe how a metamorphic rock could be made into a sedimentary rock.
3. How are rocks used to learn about the history of our planet? How does this relate to
our understanding of the processes that form different kinds of rocks? Explain using
granite, basalt, gneiss, and marble as examples. What does each of these rocks tell us
about what happened in the past?