Geology Midterm 2
Which location on this diagram would most likely record contact metamorphism in shallow levels of the crust?
1 (if in between gneiss and schist)
Which of the following is placed in the correct order (from youngest to oldest)?
1, 2 5, 3, 4
Which of the following correctly indicates which rocks are higher in metamorphic grade in the following image?
1,5
A mineral contains 3750 parent atoms and 1250 daughter atoms. If the half life for the radioactive element is 24 million years, how old is the rock?
12 million years
A mineral contains 675 parent atoms and 225 daughter atoms. If the half life for the radioactive element is 40 million years, how old is the rock?
12 million years
Which location on this diagram would result from burial to moderate depths accompanied by normal heating of rocks (regional metamorphism)?
2 (if in middle of schist)
Which location on this diagram would most likely record metamorphism along a subduction zone?
3 (if at bottom of gneiss)
A mineral contains 750 parent atoms and 7250 daughter atoms. If the half life for the radioactive element is 12 million years, how old is the rock?
42 million
Contact metamorphism is occurring at:
C
What letter(s) corresponds to areas high temperature but low pressure metamorphism?
C
Which of the following is the best way of correlating sedimentary rocks over wide distances even intercontinentally?
Index fossils and fossil assemblages
Which relative dating technique allowed you to determine which of the features in the cross-section is the youngest?
Law of Cross-cutting relations
Name the rock from the following picture:
Marble
Which of the following metamorphic rocks is made of calcite?
Marble
Name the rock from the following picture
Phyllite
Which is a metamorphic rock that is typically folded?
Phyllite
Which of the following metamorphic rocks would look shiny and have a wavy appearance?
Phyllite
From this cross section of the Grand Canyon, what is the oldest rock or structure of the ones listed below?
Precambrian metamorphic rocks and granite
Name the rock from the following picture:
Quartzite
Quartzite is a metamorphic rock that forms from a __________ parent.
Sandstone
Which of the following metamorphic rocks would have visible grains of mica and a strong foliation?
Schist
The Law of Superposition states that:
Sedimentary layers are deposited with the oldest on the bottom and the youngest on the top.
Which of the following metamorphic rocks is not paired with its true parent rock?
Slate-Basalt
What are the characteristics of an index fossil?
Widespread geographically and chronologically limited
The foliation shown in a gneiss is
a dark and light color banding
Which of the following does NOT help define foliation in metamorphic rocks?
all of the above
Which of the following does NOT match a sedimentary rock with a possible metamorphic equivalent?
all of the above
From this cross section of the Grand Canyon, what occurred between the formation of the Precambrian metamorphic rocks and the deposition of the sedimentary rocks on top?
all of these
The contact at the base of unit F in both columns:
all of these
The foliation in a schist is usually
an orientation of mica
What evidence might suggest a time interval between two rock layers?
an unconformity between the two layers
Foliated metamorphic rocks are always
caused by a directed pressure
Which would be the best relative dating technique to determine the age of a dike?
cross-cutting relations
Name the rock from the following picture
gneiss
Which of the following rocks represents the highest metamorphic grade?
gneiss
The following metamorphic rock was formed from which of the following protoliths?
granite
This figure has rock units and geologic features that are assigned letters that are not in any particular order. From the geologic relations, what is the oldest unit?
granite (unit G)
Which of the following does not match a protolith with a possible metamorphic equivalent?
granite-slate
In what environments does high pressure/low temperature metamorphism occur?
in a subduction zone
This figure has rock units and geologic features that are assigned letters that are not in any particular order. From the geologic relations, what is the youngest unit or feature of those listed below?
lava flow (unit L)
Which of the following features is younger than fault 1?
lava flow and granite
What is the source of heat during contact metamorphism?
magma
What materials were used to determine the age of the Earth?
meteorites
Which of the following metamorphic rocks is partially melted?
migmatite
Isotopes are forms of an element with different
number of neutrons
Which of the following metamorphic rocks can not form from a shale?
quartzite
Which of the following metamorphic rocks is NOT foliated?
quartzite
Which of the following metamorphic rocks is typically made of a single mineral?
quartzite
Which of the following is NOT used by geologists to determine the relative ages in a rock sequence?
radiocarbon dating
Fossils are most common in which rock types?
sedimentary
Which of the rock types would be the most difficult to numerically date?
sedimentary
Which of the following would be LEAST useful in correlating the ages of these two sequences of rocks?
sedimentation rates and bed thickness
Which of the following rocks is the finest grained?
slate
Which of the following rocks represents the lowest metamorphic grade?
slate
Which of the following lists is arranged in order from lowest to highest grade of metamorphic rock?
slate→phyllite→schist→gneiss
Which stratigraphic principle states that the sedimentary layer that is on the bottom should be the oldest?
superposition
Which of the following collection of fossils would be LEAST useful for determining the age of a section of rocks?
the fossil of a family of creatures that lived unchanged for a very long time
In regional metamorphism the source of increased temperature and pressure is _________ .
the increase in temperature with increasing depth of burial and compression
What is the youngest unit in the diagram below?
the lava flow (unit 11)
This figure shows two sections that partially overlap in age. Dashed lines show how the two sections correlate. What can you conclude from these correlations?
they were correlated based on rock types and stratigraphic position
Which of the following features is older than fault 1?
tilted layers
Which of the following is older than fault 2?
tilted layers
Tracks and burrows are examples of ________ fossils.
trace
What type of feature is represented by the boundary between geologic units 2 and 3?
unconformity
Which mineral among those listed is the most commonly used for dating very old rocks?
zircon
What would fossil ages from the geologic timescale tell us about the age of this unconformity?
All of These
This photograph shows an upper unit with fragments and a lower unit with tilted layers. Which of the following statements is true?
All of these
Which of the following is NOT a way in which fossils can be preserved?
All of these are ways a fossil can be preserved.
Which letter corresponds to high pressure but low temperature metamorphism?
B
Which kind of unconformity is probably the hardest to recognize among layered rocks because the rock strata above and below the erosional surface are parallel to each other?
Discomformity
Which of these divisions of geologic time is the longest?
Eon
Why are fossils so uncommon in rocks older than Cambrian?
Hard parts had not developed yet
