Question 1

Which of the following is ALWAYS the same for different isotopes of a single element?

Accepted Answer

A)  atomic number 
B)  atomic mass 
C)  the number of neutrons 
D)  half-life 
A)  atomic number 
B)  atomic mass 
C)  the number of neutrons 
D)  half-life A

Question 2

Basaltic clasts within a conglomerate have been radiometrically dated to 50 million years ago.Is this a reliable age for the conglomerate?

Accepted Answer

A)  Yes. 
B)  No,this age is likely too old. 
C)  No,this age is likely too young. 
D)  No,basalt never contains minerals bearing radioactive isotopes. 
A)  Yes. 
B)  No,this age is likely too old. 
C)  No,this age is likely too young. 
D)  No,basalt never contains minerals bearing radioactive isotopes. B

Question 3

What is an unconformity? Describe the three types of unconformities.

Accepted Answer

An unconformity is a boundary between two units that represents a period of nondeposition and possibly erosion and deformation.There are there types of unconformity: angular unconformity,disconformity,and nonconformity.An angular unconformity occurs when older layered rocks are tilted or folded,and then eroded.New sediment is deposited on top of that erosional surface at an angle to the older rocks' layering.A disconformity is a boundary representing a large gap in geologic time missing from the rock record due to erosion,but with the layers above and below the boundary remaining roughly parallel.A nonconformity is a boundary between two different rock types that occurs when older igneous or metamorphic rocks are eroded and younger sedimentary rocks are deposited on that erosional surface.

Question 4

How is a relative age different from a numerical age? How is each of these determined?

Accepted Answer

A relative age compares the age of one g

Question 5

Why have no rocks older than 4.03 Ga been found in the Earth's crust?

Accepted Answer

Rocks older than 4.03 Ga were

Question 6

Which principle of stratigraphy could be used to determine the relative ages of Layer 7 and Layer 3?

Accepted Answer

A)  the principle of fossil succession 
B)  the principle of original horizontality 
C)  the principle of lateral continuity 
D)  the principle of inclusions 
A)  the principle of fossil succession 
B)  the principle of original horizontality 
C)  the principle of lateral continuity 
D)  the principle of inclusions

Question 7

Within the world's sedimentary rocks,fossils

Accepted Answer

A)  are rarely,if ever,found. 
B)  are randomly distributed. 
C)  occur in limited intervals of strata. 
D)  are found only in igneous rocks. 
A)  are rarely,if ever,found. 
B)  are randomly distributed. 
C)  occur in limited intervals of strata. 
D)  are found only in igneous rocks.

Question 8

If a basalt body cuts across a fault,what are the relative ages of the basalt and the fault?

Accepted Answer

A)  The fault must be older,according to the principle of crosscutting relationships. 
B)  The basalt must be older,according to the principle of crosscutting relationships. 
C)  The basalt must be older,according to the principle of original horizontality. 
D)  Their relative ages cannot be determined from the information given. 
A)  The fault must be older,according to the principle of crosscutting relationships. 
B)  The basalt must be older,according to the principle of crosscutting relationships. 
C)  The basalt must be older,according to the principle of original horizontality. 
D)  Their relative ages cannot be determined from the information given.

Question 9

If the lithology and fossil content of two bodies of rock on opposite sides of a canyon are identical,then these remaining outcrops were likely physically connected at one time and formed part of an extensive,sheet-like layer of rock.This idea summarizes the principle of:

Accepted Answer

A)  superposition. 
B)  lateral continuity. 
C)  original horizontality. 
D)  uniformitarianism. 
A)  superposition. 
B)  lateral continuity. 
C)  original horizontality. 
D)  uniformitarianism.

Question 10

Which statement best summarizes the development of the geologic time scale?

Accepted Answer

A)  Numerical ages for rocks were known before the relative sequence of sedimentary layers was established. 
B)  Relative ages for sedimentary strata were known before accurate numerical dates for these rocks were measured. 
C)  Names of relative ages (such as Silurian)and accurate numerical dates for these ages became known at about the same time. 
D)  Numerical ages for fossils were known before the relative sequence of sedimentary layers was established. 
A)  Numerical ages for rocks were known before the relative sequence of sedimentary layers was established. 
B)  Relative ages for sedimentary strata were known before accurate numerical dates for these rocks were measured. 
C)  Names of relative ages (such as Silurian)and accurate numerical dates for these ages became known at about the same time. 
D)  Numerical ages for fossils were known before the relative sequence of sedimentary layers was established.

Question 11

If horizontal sedimentary strata overlie tilted strata (and no fault is present),the surface between the horizontal and tilted strata must be a(n)

Accepted Answer

A)  conformable sedimentary contact. 
B)  angular unconformity. 
C)  disconformity. 
D)  nonconformity. 
A)  conformable sedimentary contact. 
B)  angular unconformity. 
C)  disconformity. 
D)  nonconformity.

Question 12

Describe the plausible geologic history of the rocks in the following photo/diagram.

Accepted Answer

The sediments that make up the sandstone

Question 13

Which method of correlation is most reliable for determining age equivalence among bodies of rock that are physically separated by vast distances?

Accepted Answer

A)  lithologic correlation 
B)  fossil correlation 
C)  inclusion correlation 
D)  unconformity correlation 
A)  lithologic correlation 
B)  fossil correlation 
C)  inclusion correlation 
D)  unconformity correlation

Question 14

Compare and contrast lithologic correlation and fossil correlation.In what circumstance is each most useful? Provide an example of each.

Accepted Answer

Student answers may include examples sim

Question 15

In an unweathered sample of igneous rock,the ratio of an unstable isotope to its stable daughter isotope is 1:15.If no daughters were present at the time the rock cooled below closure temperature,and the half-life of the isotope is 50 million years,how old is the rock?

Accepted Answer

A)  200 million years 
B)  400 million years 
C)  750 million years 
D)  1 billion years 
A)  200 million years 
B)  400 million years 
C)  750 million years 
D)  1 billion years

Question 16

Why is radiocarbon dating rarely applied in geological work?

Accepted Answer

A)  No substances on the Earth contain significant amounts of carbon-14. 
B)  The half-life of carbon-14 is so long that it is effectively a stable isotope. 
C)  The half-life of carbon-14 is so short that it can only be used to date materials that are less than 70,000 years old. 
D)  Carbon-14 is destroyed by the heat of magma. 
A)  No substances on the Earth contain significant amounts of carbon-14. 
B)  The half-life of carbon-14 is so long that it is effectively a stable isotope. 
C)  The half-life of carbon-14 is so short that it can only be used to date materials that are less than 70,000 years old. 
D)  Carbon-14 is destroyed by the heat of magma.

Question 17

Numerical ages for boundaries between time units on the geologic time scale primarily resulted from the study of ________,in conjunction with relative age information determined from geologic principles.

Accepted Answer

A)  fossil content and spatial relationships among igneous rocks 
B)  fossil content and spatial relationships among sedimentary rocks 
C)  radiometric dating of igneous rocks 
D)  radiometric dating of sedimentary rocks 
A)  fossil content and spatial relationships among igneous rocks 
B)  fossil content and spatial relationships among sedimentary rocks 
C)  radiometric dating of igneous rocks 
D)  radiometric dating of sedimentary rocks

Question 18

Discuss what the numerical age represents when a basalt,a gneiss,and a sandstone are dated using radiometric techniques.

Accepted Answer

The numerical age of a basalt tells us w

Question 19

Can the age of the Earth be reliably estimated from sediment thicknesses?

Accepted Answer

A)  Yes.Sedimentation rates remain constant at any one locality throughout the Earth's history. 
B)  Yes.Sedimentary rocks are rarely metamorphosed or melted. 
C)  No.Sedimentary rocks make up only a small fraction of the rocks on the Earth's surface. 
D)  No.Most of the Earth's history is represented by unconformities between strata rather than the strata themselves. 
A)  Yes.Sedimentation rates remain constant at any one locality throughout the Earth's history. 
B)  Yes.Sedimentary rocks are rarely metamorphosed or melted. 
C)  No.Sedimentary rocks make up only a small fraction of the rocks on the Earth's surface. 
D)  No.Most of the Earth's history is represented by unconformities between strata rather than the strata themselves.

Question 20

James Hutton,the "father of geology," put forth the principle of

Accepted Answer

A)  superposition. 
B)  original continuity. 
C)  original horizontality. 
D)  uniformitarianism. 
A)  superposition. 
B)  original continuity. 
C)  original horizontality. 
D)  uniformitarianism.

Exam 10: Deep Time: How Old Is Old

Which of the following is ALWAYS the same for different isotopes of a single element?

Basaltic clasts within a conglomerate have been radiometrically dated to 50 million years ago.Is this a reliable age for the conglomerate?

What is an unconformity? Describe the three types of unconformities.

How is a relative age different from a numerical age? How is each of these determined?

Why have no rocks older than 4.03 Ga been found in the Earth's crust?

Which principle of stratigraphy could be used to determine the relative ages of Layer 7 and Layer 3?

Within the world's sedimentary rocks,fossils

If a basalt body cuts across a fault,what are the relative ages of the basalt and the fault?

If the lithology and fossil content of two bodies of rock on opposite sides of a canyon are identical,then these remaining outcrops were likely physically connected at one time and formed part of an extensive,sheet-like layer of rock.This idea summarizes the principle of:

Which statement best summarizes the development of the geologic time scale?

If horizontal sedimentary strata overlie tilted strata (and no fault is present),the surface between the horizontal and tilted strata must be a(n)

Describe the plausible geologic history of the rocks in the following photo/diagram.

Which method of correlation is most reliable for determining age equivalence among bodies of rock that are physically separated by vast distances?

Compare and contrast lithologic correlation and fossil correlation.In what circumstance is each most useful? Provide an example of each.

In an unweathered sample of igneous rock,the ratio of an unstable isotope to its stable daughter isotope is 1:15.If no daughters were present at the time the rock cooled below closure temperature,and the half-life of the isotope is 50 million years,how old is the rock?

Why is radiocarbon dating rarely applied in geological work?

Numerical ages for boundaries between time units on the geologic time scale primarily resulted from the study of ________,in conjunction with relative age information determined from geologic principles.

Discuss what the numerical age represents when a basalt,a gneiss,and a sandstone are dated using radiometric techniques.

Can the age of the Earth be reliably estimated from sediment thicknesses?

James Hutton,the "father of geology," put forth the principle of

The Earth in Context

The Way the Earth Works: Plate Tectonics

Patterns in Nature: Minerals

Up From the Inferno: Magma and Igneous Rocks

The Wrath of Vulcan: Volcanic Eruptions

Pages of the Earths Past: Sedimentary Rocks

Metamorphism: a Process of Change

A Violent Pulse: Earthquakes

Crags,cracks,and Crumples: Crustal Deformation and Mountain Building

A Biography of the Earth

Riches in Rock: Energy and Mineral Resources

Unsafe Ground: Landslides and Other Mass Movements

Streams and Floods: the Geology of Running Water

Restless Realm: Oceans and Coasts

A Hidden Reserve: Groundwater

Dry Regions: the Geology of Deserts

Amazing Ice: Glaciers and Ice Ages

Global Change in the Earth System

Introducing Rocks

A Surface Veneer: Sediments and Soils

The Rock Cycle

The Earth’s Interior Revisited: Insights from Geophysics

Memories of Past Life: Fossils and Evolution

Ever-Changing Landscapes and the Hydrologic Cycle

Prelude: And Just What is Geology?

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