GEO 101 Chapter 10 Study Guide

James Hutton, the “father of geology”, put forth the principle of _______________.

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

D

As understood by modern geologists, the principle of uniformitarianism implies that _______________.

A. the Earth has always had the basic appearance that it has today, which the distributions of ocean basins and continents identical to what we see today
B. igneous, metamorphic, and sedimentary rocks are uniformly mixed throughout the crust of the Earth
C. physical processes observed today (such as erosion and volcanic eruption) have been active in the past and are responsible for the geologic history we see preserved in the rock record
D. physical processes observed today (such as erosion and volcanic eruption) have been occurring throughout Earth history at constant rates; for example, no eruption in geologic time would have been greater than the 1815 Tambora eruption

C

In an undisturbed sequence of sedimentary rocks, younger layers overlay older layers, according to the principle of _______________.

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

A

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 _______________.

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

B

Which of the following geologic principles is a direct result of gravity?

A. baked contacts
B. cross-cutting relationships
C. original horizontality
D. inclusions

C

Relative ages expressed on the geologic time scale primarily resulted from the study of _______________.

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

B

Numerical ages for boundaries between time units on the geologic time scale primarily resulted from the study of _______________, in conjunction with relative age data.

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

C

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

A. conformable sedimentary contact
B. angular uncomformity
C. disconformity
D. nonconformity

B

The surface below sedimentary rocks that overlie igneous or metamorphic rocks is termed a(n) _______________.

A. disconformity
B. angular unconformities
C. nonconformity

C

Buried erosional surfaces between parallel sedimentary strata are termed _______________.

A. disconformities
B. angular unconformities
C. nonconformities

A

Which method of correlation is more reliable for determining relative ages of rock units over broad area?

A. lithologic correlation
B. fossil correlation

B

Two atoms of a single element that differ in number of neutrons are said to represent two distinct _______________ of that element.

A. isomers
B. isotopes
C. isotherms
D. atomic species

B

Which proportion of a radioactive isotope is expected to remain in an unaltered (unreacted) state after the passage of three half-lives?

A. one-third
B. three-halves
C. one-eighth
D. one-sixth

C

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, and the half-life of the reaction is 50 million years, how old is the rock?

A. 200 million years
B. 400 million years
C. 750 million years
D. none of the above

A

Radiometric dates applied to sedimentary rocks produce ages that are _______________.

A. just as accurate as when the technique is applied to igneous rocks
B. too young (postdate sedimentary deposition)
C. too old (predate sedimentary deposition)

C

If the numerical ages of two formations are known, then the relative age of each with respect to one another can be inferred.

A. True
B. False

A

If the relative age of two formations (with respect to one another) is known, then the numerical ages for each formation can be inferred.

A. True
B. False

B

In the area immediately surrounding an igneous intrusion, a host limestone is locally metamorphosed to produce marble. Which of the following statements is correct?

A. The intrusive igneous rock must be older than limestone.
B. The limestone must be older than the marble.
C. The marble must be older than the intrusive rock.
D. The relative ages of the three units cannot be determined with the information given.

B

The Earth is approximately 4.6 billion years old.

A. True
B. False

A

The surfaces named contacts #2 and #3 are examples of _______________.

A. conformable sedimentary contacts
B. faults
C. baked contacts
D. unconformities

D

Contact #1 is an example of a(n) _______________.

A. conformable sedimentary contacts
B. faults
C. baked contacts
D. unconformities

B

The oldest geologic unit in the cross section is the _______________.

A. granite
B. marble
C. limestone
D. sandstone

C

The youngest geologic unit visible in the cross section is the _______________.

A. granite
B. limestone
C. conglomerate
D. marble

C

The marble rind surrounding the granite pluton must be younger than the limestone according to the principle of .
A. superposition
B. baked contacts
C. original horizontality
D. original continuity
B

Concerning relative ages of the shale and sandstone, .
A. the shale must be older, according to the principle of superposition
B. the sandstone must be older, according to the principle of superposition
C. the shale must be older, according to the principle of components
D. their relative ages cannot be determined from the information given
A

Concerning relative ages of the granite and sandstone, .
A. the granite must be older, according to the principle of superposition
B. the sandstone must be older, according to the principle of superposition
C. the granite must be older, according to the principle of components
D. their relative ages cannot be determined from the information given
D

Basaltic clasts within the basal layers of the conglomerate imply which of the following statements?
A. The conglomerate must be the older of the two.
B. The basalt must be the older of the two.
B

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

Concerning the relative ages of the basalt and the fault, .
A. the fault must be older, according to the principle of cross-cutting relationships
B. the basalt must be older, according to the principle of cross-cutting 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
B

Contact #3 is both a at various points.
A. conformable contact and an unconformity
B. fault and an unconformity
C. nonconformity and an angular unconformity
D. disconformity and a nonconformity
D

Which statement about contact #3 is correct?
A. It and contact #2 once formed a continuous unconformity.
B. It was once elevated farther above contact #2, but faulting has brought them closer together.
C. It presents an example of an angular unconformity
D. It must be younger than the conglomerate, due to the principle of baked contacts.
A