geo 101 ch. 16 post reading quiz

Geologic time is measured by _______________.

a. numerical dating only

b. relative and numerical dating

c. relative dating only

d. the dating of rocks, boulders, and other geological objects

B

In the early 18th and 19th centuries, which of the following is the primary reason for the inability to determine Earth's age?

a. They were unable to determine the total thickness of sedimentary rock in the Earth's crust.

b. Scientists were unable to determine deposition rates for various types of sediment.

c. They were unable to estimate how much of a rock had been removed by erosion.

d. Scientists were unaware that there were different types of sediment in this time period.

c

Landon is studying the Scottish geologist, James Hutton, and why his findings resulted in him being known as the father of modern geology. He discovered his studies of rock exposure were instrumental in determining the principle of uniformitarianism; why?

a. James Hutton's findings showed catastrophic events do not play a role in geology.

b. James Hutton's findings indicated geological processes have not acted in the same manner throughout time.

c. James Hutton's findings indicated each geologic event is significantly different than the next and may or may not be able to be explained.

d. James Hutton's findings indicated the geologic processes operating to modify the Earth's crust have acted in the same general manner with approximately the same intensity throughout history.

D

______________ illustrates that because sedimentary particles settle from water under the influence of gravity, sediment is deposited in essentially horizontal layers.

a. Principle of original horizontality

b. Principle of superposition

c. Principle of lateral continuity

d. Principle of cross-cutting relationships

A

The principle of _________ is the basis for relative-age determinations of strata and their contained fossils.

a. cross-cutting relationships

b. lateral continuity

c. original horizontality

d. superposition

D

James Hutton identified the principle of cross-cutting, which indicates that an intrusive igneous structure is younger than the rock it intrudes. But this principle is not fully effective because _______.

a. the association of sedimentary and igneous rocks may cause problems in relative dating

b. buried lava appears to be significantly different than sedimentary rock in the strata.

c. scientists cannot be certain that buried lava flow is older than the rocks above it

d. a sill, resulting from later igneous intrusion, is significantly older than all the beds below it

A

Which of the following is not correct regarding unconformities?

a. Unconformities completes the geologic record.

b. Unconformities represent times of nondeposition.

c. Unconformities represent times of erosion.

d. Unconformities often encompass millions or tens of millions of years.

A

In order to decipher Earth history, geologists search for regions they are most likely to gain the most information. Is there any location in the world that has all of the geographic information for the geologic timeline in the same place?

a. No, no single location in a region has a geologic record of all events that occurred throughout its history.

b. Yes, there are regions that have a geologic record of all the events that occurred throughout its history but we have not yet found it.

c. Yes, geologists in earlier centuries found areas where all geologic information could be found in one place, but we have been unable to locate the exact location they were in.

d. Yes, due to the forces of erosion, there are areas that are naturally constructed perfectly for intense study.

A

Lisa is studying time indicators in geology and is currently focused on the ability of fossils to determine geologic time. She found that fossils can be useful as relative time indicators for all the following reasons except _____________________.

a. they are not easily identifiable in most cases

b. they are the remains of organisms that lived in the geologic past

c. they are geographically widespread

d. fossils that existed for a relatively short amount of time can serve as a guideline

A

Why is radioactive decay important to geologists studying the geologic timeline?

a. Radioactive decay explains the reason for Earth's internal heat.

b. Radioactive decay explains why volcano eruptions are relatively predictable.

c. Radioactive decay is responsible for most of Earth's erosion.

d. Radioactive decay releases the energy necessary to develop rocks.

A

A(n) _________________ is an erosional surface on tilted or folder strata over which younger strata were deposited.

a. disconformity

b. nonconformity

c. angular conformity

d. comfortable strata

c

A(n) __________ is difficult to recognize because it frequently resembles an ordinary bedding plane.

a. comfortable strata

b. nonconformity

c. disconformity

d. angular conformity

C

Geologists are in the laboratory discussing decay rates that they often refer to in terms of the half-life. The half-life of a radioactive element is constant and can be precisely measured. How does the half-life of an element affect how geologists date a sample?

a. Geologists can determine how many atoms are in a sample. Based on the number of atoms in the sample, geologists can approximate the age of the sample.

b. Geologists can date a sample using their knowledge of the half-life of a radioactive element, but they are only able to go back as far as 500 years ago in the geologic timeline using this method.

c. By measuring the parent-daughter ratio and knowing the half-life of a parent, geologists can calculate the age of a sample that contains a radioactive element.

d. Water temperature and wave period

C

To obtain accurate radiometric dates, geologists must be certain they are dealing with a closed system. Why do scientists need a closed system to determine an accurate date?

a. If there is not a closed system, it means daughter or parent atoms may have leaked out of the system.

b. In a closed system, there are not any radioactive elements.

c. If there is not a closed system, crystallization has not yet occurred, and the estimated date will be inaccurate.

d. In a closed system, there is no radioactive decay.

A

The _____________ method is typically used for dating fine-grained volcanic rocks from which individual crystals cannot be separated.

a. lead-thorium

b. potassium-argon

c. uranium-lead

d. rubidium-strontium

B

Which of the following is incorrect regarding the carbon-14 dating method?

a. Carbon-14 is used only to date living materials.

b. Carbon is one of the basic elements found in all forms of life and has three isotopes.

c. Carbon-14 is a radioactive element.

d. The carbon-14 dating technique is based on the ratio of carbon-14 to carbon-12.

A

Which of the following is incorrect regarding the development of the geologic time scale?

a. By the beginning of the 20th century, geologists had developed a relative geologic time scale but did not yet have any numerical dates for time-unit boundaries.

b. Radiometric dates were added to the geologic time scale in the late 19th century.

c. Sedimentary rocks, with rare exceptions, cannot be radiometrically dated.

d. The development of the geologic time scale was completed by one scientist: James Hutton.

D

There are two types of units referring to time and their relationship in geology. If you're reviewing time-stratigraphic units, you're studying which of the following?

a. The material bodies of rock that occupy a position in a sequence of strata

b. The period of time the rocks were deposited

c. If the body of rock was divided into the early, middle, or late subdivision

d. The approximate year the rock began to develop

A

Which of the following best explains why geologists are critical in understanding the Earth's climate today?

a. The fossils of plants and animals can tell scientists about the environment and climate in various time periods and provide an idea of what is happening in today's world.

b. Geologists are critical in understanding the Earth's climate today because they can review the geographic timeline and allow scientists to understand what human-related factors are contributing to global warming.

c. Geologists can review the Earth's core temperature throughout history and compare it to today's allowing them to understand which factors are contributing to climate change.

d. Geologists can determine why climate change is occurring based on the various ages of volcanic rock.

A

A _____________ is when an erosional surface cut into metamorphic or igneous rocks is covered by sedimentary rocks.

a. nonconformity

b. general unconformity

c. angular conformity

d. disconformity

A

Each of the following are units used to refer to specific intervals of geologic time except ___________.

a. epoch

b. period

c. eon

d. strata

D

The geological time scale developed by many geologists dates back as far as _____________ years ago.

a. 4 billion

b. 1 billion

c. 5 million

d. 1 million

A

________________ is the process of determining the age of an event as compared to other events.

a. Relative dating

b. Numerical dating

c. Radiometric dating

d. carbon-14 dating

A

Which of the following is not true regarding a guide fossil?

a. Guide fossils are not easily identified but provide an approximate year of development to geologists.

b. Guide fossils are easily identified by geologists.

c. Guide fossils have an extensive geographic distribution.

d. Guide fossils have a short geologic range.

A