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