A few sample MC on metamorphic rocks…. Marble is a metamorphic rock that forms from __________? A....
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Transcript of A few sample MC on metamorphic rocks…. Marble is a metamorphic rock that forms from __________? A....
A few sample MC on metamorphic rocks….
Marble is a metamorphic rock that forms from __________?
A. graniteB. limestoneC. sandstoneD. shale
Answer = B (page 193)
A few sample MC on metamorphic rocks….
What is the pressure on a rock at 15 kilometers depth in the Earth’s crust?
A. approximately 4 times atmospheric pressureB. approximately 40 times atmospheric pressureC. approximately 400 times atmospheric pressureD. approximately 4000 times atmospheric pressure
Answer = D (page 195)
A few sample MC on metamorphic rocks….
Which of the following processes will cause metamorphism?
A. an increase in pressureB. an increase in temperatureC. interaction with hydrothermal fluidsD. all of the above
Answer = D (page 194)
A few sample MC on metamorphic rocks….
What type of metamorphism is caused by high temperature and high pressure imposed over a large volume of crust?
A. burialB. contactC. regionalD. shock
Answer = C (page 197)
A few sample MC on metamorphic rocks….
Which of the following is not used to classify foliated rocks?
A. the metamorphic gradeB. the nature of the foliationC. the size of the crystalsD. the texture of the parent rock
Answer = D (pages 199-202)
A few sample MC on metamorphic rocks….
Which of the following statements about the metamorphism of a shale is false?
A. With increasing metamorphism, clay minerals break down to form micas.B. With increasing metamorphism, the grain size of the rock gets smaller.C. With increasing metamorphism, foliation develops.D. With increasing metamorphism, the amount of water in the rock decreases.
Answer = B (page 200)
TODAY: Chapter 10
Geologic Time 1) Relative dating principles2) Correlation of rock layers3) Absolute dating w/ radioactivity4) Geologic time scale
Chapter 10
Study questions 1. What is the difference between absolute and relative dates, and how are they
determined? Know the principles of original horizontality and superposition.2. Learn the basics of fossils and how they’re used, concepts of faunal
succession, formation. 3. How do we correlate rock layers in different regions?4. What are the different types of unconformities, how do you apply cross-
cutting relationships to determine the relative sequence of strata? 5. How was the geologic time-scale created? Study the most important divisions
(eons, eras) of the geological time scale and extinctions between major divisions.
6. How do apply radioactive decay of some elements to add absolute dates to the geologic time scale (radiometric dating)?
“Telling time geologically”
Earth’s history concealed in rocks
Goal of geology: unraveling Earth’s history
Principle time keeping devices:
Relative dating - putting rocks/events in proper order
Absolute dating - determining rocks/event’s actual age
1. Relative Dating: Key principles
1. Relative Dating: Key principles
Law of superpositionLaw of superposition
Principle of original horizontalityPrinciple of original horizontality
Principle of cross-cutting relationshipsPrinciple of cross-cutting relationships
InclusionsInclusions
UnconformitiesUnconformities
T&L Figure 8.2
A bed of rock is older than that above, younger than that belowA bed of rock is older than that above, younger than that below
Superposition is well illustrated by the strata in the Grand Canyon
Law of superpositionLaw of superposition
Principle of original horizontalityPrinciple of original horizontality
Principle of cross-cutting relationshipsPrinciple of cross-cutting relationships
InclusionsInclusions
UnconformitiesUnconformities
A bed of rock is older than that above, younger than that belowA bed of rock is older than that above, younger than that below
T&L Figure 8.3
1. Relative Dating: Key principles
Sedimentary layers deposited flatSedimentary layers deposited flat
Law of superpositionLaw of superposition
Principle of original horizontalityPrinciple of original horizontality
Principle of cross-cutting relationshipsPrinciple of cross-cutting relationships
UnconformitiesUnconformities
A bed of rock is older than that above, younger than that belowA bed of rock is older than that above, younger than that below
Sedimentary layers deposited flatSedimentary layers deposited flat
Faults & dikes are younger than beds they crossFaults & dikes are younger than beds they cross
1. Relative Dating: Key principles
See Figure Story 10.11
UnconformitiesUnconformities
(Conformable layers: deposited w/out interruption)
1. Relative Dating: Key principles
An unconformity is a break in the rock record produced An unconformity is a break in the rock record produced by erosion and/or nondeposition of rock unitsby erosion and/or nondeposition of rock units
1. Relative Dating: Key principles
Example: Grand Canyon
Has record of a huge expanse in time, and multitude of sedimentary environments…
But: The record of time is not continuous because of geological processes that happened after deposition.
Movie: watch for terminology of different kinds of Unconformities and relative dating methods
Relative Dating: Key principles UnconformitiesUnconformities
3 types
Angular unconformity
Disconformity
Nonconformity
Relative Dating: Key principles UnconformitiesUnconformities
3 types
Angular unconformity
Disconformity
Nonconformity
Tilted/folded sedimentary rocks overlain by younger, more flat layers
See Fig. 10.6
Deposition
Folding/Uplift
Erosion
Subsidence/more erosion
Recipe for an angular unconformity
See Fig. 10.8
Relative Dating: Key principles UnconformitiesUnconformities
3 types
Angular unconformity
Disconformity
Nonconformity
Layers on either side of unconformity are parallel
See Fig. 10.7
Relative Dating: Key principles UnconformitiesUnconformities
3 types
Angular unconformity
Disconformity
NonconformityInterface between sedimentary layers and metamorphic or igneous rock