geologic time quiz

1.

1 point

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

just as accurate as when the technique is applied to igneous rocks.

too young (postdate sedimentary deposition)

too old (predate sedimentary deposition)

2.

1 point

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

the Earth has always had the same basic appearance that it has today, with the distributions of ocean basins and continents identical to what we see today

igneous, metamorphic, and sedimentary rocks are uniformly mixed throughout the crust of the Earth

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

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

3.

1 point

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

superposition

original continuity

original horizontality

uniformitarianism

4.

1 point

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

The intrusive igneous rock must be older than the limestone.

The limestone must be older than the marble.

The marble must be older than the intrusive rock.

The relative ages of the three units cannot be determined with the information given.

5.

1 point

Buried erosional surfaces between parallel sedimentary strata are termed ____________.

disconformities

angular unconformities

nonconformities

6.

1 point

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

disconformity

angular unconformity

nonconformity

7.

1 point

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

one-third

three-halves

one-eighth

one-sixth

8.

1 point

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 ____________.

superposition

original continutity

original horizontality

uniformitarianism

9.

1 point

Numerical ages for recent geologic events can sometimes be determined by the study of ____________.

layering (growth lines) in shells

annual growth rings in trees

seasonal layering in glacial ice

all of the above

10.

1 point

The correct answer to question 7 illustrates the principle of ____________.

baked contacts

cross-cutting relationships

original horzontality

inclusions