Geology 101
Name __________________
Reading Guides for Ch. 7 ( Metamorphism & Metamorphic Rocks) and Ch. 8: (Telling Time Geologically)
Chapter 7: Metamorphism & Metamorphic Rocks (p.204)
Chapter Introduction:
The third major group of rocks is metamorphic rocks. “Metamorphism is the process by which heat, pressure, and
chemical reactions deep within the Earth alter the mineral content and/or structures of preexisting rock (with/
without) ___________melting.“
As the introduction states: it is possible to see many volcanic and sedimentary processes at the surface of the Earth, but by
definition we cannot directly observe the formation metamorphic rocks.
What Drives Metamorphism? (p. 207)
“Metamorphic processes _____________________(Do/Do not) break all the bonds in a rock’s minerals.
Heat (p. 207)
“When a rock moves from near-surface conditions to a greater depth by tectonic movement or by deep burial under
sedimentary deposits, it is _________________ up and _____________________________.
Friction is NOT a
major source of thermal energy inside the Earth. Some frictional heating occurs along faults, but this is minor in comparison to the
Earth’s heating from radioactive decay.
Pressure (p. 208)
Define Foliation:
Explain how foliation develops:
Circulating Fluids (p. 210)
Some interesting ideas in this section. You will need to know that circulating fluids influence metamorphism, but you will not be
tested over the detailed information in this section.
What Controls the Mineralogy of a Metamorphic Rock ? (p. 210)
“The factors that controls the mineralogy of a metamorphic rock include some of the variables that you just learned
about-______________________________, __________________________________, and the amount and
composition of fluids. There is one other critical factor: the _______________________________________.”
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Types of Metamorphism (p. 210)
Contact metamorphism is normally associated with:
This type of metamorphic alteration tends to ____________ (increase/decrease) the farther you are from the contact.
Regional metamorphism alters rocks for _______________and has produced vast amounts of exposed metamorphic rocks in which
parts North America?
Explain how burial metamorphism occures:
Shock metamorphism occurs when:
Other Types of Metamorphism (p. 212-213)
The other types of metamorphism are also interesting, The hydrothermal metamorphism is applicable to rocks in Washington. We
find examples of the serpentinization in several parts of Washington.
Common Metamorphic Rocks (p. 213)
You should be familiar with the following rocks types, their possible parent rocks, and what they tell us about the history of
metamorphism (or metamprohic Grade) when we find them:
gneiss, marble, phyllite, quartzite, slate, schist,
Circle the rocks listed above that are always foliated.
Classification and Derivation of Some Common Metamorphic Rocks (p. 213)
List one possible parent rock for each metamorphic rock listed below that are always foliated.
Marble =
, phyllite =
, quartzite =
, slate =
Temperatures and Pressures of Metamorphism, ( p. 219)
Metamorphic Grade (p. 219)
Minerals are stable in only certain ranges of temperature and pressure. If the mineral is exposed to higher or lower
temperatures/pressures, the mineral will change to another mineral. This idea leads to the concept that we can use the specific
minerals in a metamorphic rock to determine the history of temperature and pressure for the rock. This concept is important in
understanding metamorphic rocks, but I will not expect you to know the various types of metamorphic facies noted on page 222.
Plate Tectonics and Metamorphic Rocks (p. 223) and Metamorphic Rocks in Daily Life (p. 223) We will return to the section
on plate tectonics later in the quarter You may read these sections now or later.
The Rock Cycle Revisited (p.226): No new ideas here, but a good review of this important concept!
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Ch. 8: Telling Time Geologically
Please read the introduction to the chapter. (p. 230)
Geologic Time in Perspective (p.232)
We use two methods of examining time, __________________ dating and _______________ dating.
Describe the difference between these two methods:
Determining Relative Age (p. 233)
Principles of Relative Dating (p.234)
Geologic processes that modify the Earth’s surface today have acted in the same manner in the past. This principle is
termed _____________________. This principle does not imply that the __________ at which processes occur is
the same.
Give an example of this principle:
Matching:
A. principle of uniformitarianism,
D. principle of crosscutting relationships
B. principle of original horizontality C. principle of superposition
E. principle of inclusions
F. principle of faunal succession
________ 1. Any intrusive rock, such as a dike or a sill, must be younger than the rock it cuts.
________ 2. Geological processes operating today operated in a similar manner in the past.
________ 3. Animals on Earth have changed in a definite order: earlier forms were simpler than later forms.
________ 4. The rocks at the bottom of a sequence are older than the ones at the top.
________ 5. Fragments of other rocks contained in another rock, must be older than the host rock
________ 6. Most layers of sedimentary material are deposited in horizontal or near-horizontal layers.
Why are index fossils important in constructing the history of an area?
Please read the Highlight 8-1 (p 238-240) -- How Fossils Form
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Unconformities (p. 237): What is an unconformity?
You need to be able to recognize all types of unconformities listed in this section and know that they are unconformities, but I will
not ask you to know the names of these different types of unconformities. Unconformities are an important part of the history of an
area because they may be the only part of the record that is an evidence of erosion.
Make sure that you include unconformities in any geological history you complete.
Relative Dating by Weathering Features (p. 245) Interesting section with some potential local application, but you will not be
tested over this section.
Determining Numerical Age (p.246) & Isotope Dating (p.246)
What do the terms “parent” and “daughter’ isotope refer to?
What types of samples are analyzed by carbon-14? Why is this method not used more widely in geology?
Other Numerical-Dating Techniques (p. 252) These methods are interesting, but you will not be tested over this section
Combining Relative and Numerical Dating (p. 258). The diagrams in Figure 8-32 are useful and you should be able to work
through a similar diagram and determine the geological history.
The Geological Time Scale (p.259)
I will not ask you on a test or in lab to know this scale. The terms are used to communicate events that occurred during an interval
of time. For example, the Cambrian is a period of years, from 570 million years to 505 million years.
Life and Death on Earth (p.260 to 263) Both of these sections are interesting and I recommend that you read them, but I will not
test you over the information in these two sections beyond the aspect we cover in class.
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