Chapter Questions
Match each definition with the correct vocabulary term from the Study Guide.
the record of Earth's history from its origin to the present
a gap in the rock record caused by erosion
the emission of radioactive isotopes and the resulting change into other products over time
the largest time unit in the geologic time scale
the matching of unique outcrops among regions
Distinguish between the vocabulary terms in each pair.period, epoch
Distinguish between the vocabulary terms in each pair.
altered hard part, original preservation
absolute-age dating, relative-age dating
fossil, index fossil
mold, cast
The sentences below are incorrect. Make each sentence correct by replacing the italicized word or phrase with a term from the Study Guide.
Original horizontality is the principle that a fault or intrusion is younger than the rock it intersects.
Relative-age dating states that processes operating today have been operating since Earth formed.
A varve is a sedimentary layer used to match rock layers across large areas.
Correlation is the change in species over time.
The end of which era is marked by the largest extinction event in Earth's history?A. CenozoicB. MesozoicC. PaleozoicD. Precambrian
How old is a mammoth's tusk if 25 percent of the original C-14 remains in the sample? The half-life of $C-14$ is 5730 years.A. 5730 yearsB. 11,460 yearsC. 17,190 yearsD. 22,920 years
Which time period is missing in the diagram?A. CambrianB. PermianC. TriassicD. Paleogene
Which is not a typical characteristic of an index fossil?A. was commonplace while aliveB. existed for a long period of timeC. is geographically widespreadD. is easily recognizable
Which is the smallest division of geologic time?A. periodB. eonC. eraD. epoch
Which geologic principle is used when a geologist observes an outcrop of rocks and determines that the bottom layer is the oldest?A. uniformitarianismB. original horizontalityC. superpositionD. inclusion
Uranium-238 breaks down into thorium-234. Which is thorium-234 in relation to uranium-238?A. parentB. brotherC. sonD. daughter
What does the diagram show?A. uniformitarianismB. inclusionC. cross-cutting relationshipsD. correlation
Trees that have been buried by volcanic ash are likely to be preserved in which manner?A. original preservationB. mummificationC. mineral replacementD. recrystallization
Which are glacial lake sediments that show cycles of deposition?A. annual ringsB. tillitesC. varvesD. unconformities
Sequence the steps by which a mold and a cast are formed.
Explain why mass extinctions are important to geologists.
Compare and contrast absolute-age dating and relative-age dating.
Assess the usefulness of a universally accepted geologic time scale.
Explain, in your own words, why an unconformity is any gap in the rock record.
Argue for or against making the time units of the geologic time scale of equal duration.
Relate How are microscopic fossils associated with discovering oil at a particular site?
Identify the oldest rock layer in the diagram.
Find an angular unconformity in the diagram.
Apply List the order of geologic events in the diagram from oldest to youngest along with the geologic principles that you used.
Critique this statement: The principles for determining relative age are based on common sense.
Create One way to remember the order of words in a sequence is to create a phrase, called an acrostic, that uses the same first letter of each word in the sequence. For example, "My Dear Aunt Sally" is often used to remember the mathematical order of operations: Multiply and Divide before you Add and Subtract. Create an acrostic to help you remember the periods of the Phanerozoic Eon.
Solve The half-life of K-40 is $1.3$ billion years. What is the age of an ancient igneous rock that contains a mineral with $12.5$ percent $\mathrm{K}-40$ and $87.5$ percent Ar- 40 ?
Compare and contrast an index fossil and a key bed.
Assess whether a clam or a spider has a better chance at becoming a fossil.
Evaluate Can radiocarbon dating be used to determine the age of a dinosaur bone? Explain.
What does the red dot signify on the graph?
A geologist discovers wood buried within sediments of a landslide that is thought to have been caused by an ancient earthquake. Explain two methods that the geologist could use to determine when the earthquake occurred.
Create a concept map using the following terms: absolute-age dating, geologic time scale, relativeage dating, fossils, unconformities, and radiometric dating.
Do you think domestic dogs might make good index fossils for future geologists? Explain.
Imagine that you are a bacterium that lives for only 20 minutes. Explain how your observations about the world would be different from those of a human being who lives for about 80 years. Evaluate the difference between human time and geologic time.
With what do the largest drops in diversity coincide on the geologic time scale?
Explain what the decreases in diversity mean.
Use the information in the graph to support adding one or more new eras to the Phanerozoic.
What subatomic particles make up the nucleus of an atom?
Why do tornadoes occur most frequently in the central United States?