GEOL 101 Chapter 15

Which image is an example of an angular unconformity? SEE IMAGES BELOW FOR ANSWER SELECTIONS.

In the images below, which contains a disconformity?

What does the term unconformity mean?

In the following rock sequence, how much erosion might have occurred between rock layer A and rock layer B?

What characteristic most directly DISTINGUISHES an angular unconformity from a nonconformity?

Which list best describes the events that would lead to the layering of sedimentary rocks in this diagram?

Which of the following statements about relative and absolute age dating is most accurate?

What is the principle of original horizontality?

What is the principle of superposition?

What is the principle of cross-cutting relationships?

Five layers of rock are cut by two faults. Both faults cut through all five layers of rock. Fault A breaks through to the surface, whereas fault B does not. Which of the following statements about faults A and B is most accurate?

Which principle of relative age dating is important for determining the relative age of igneous rock that has intruded into overlying rock?

A fault (F) breaks three layers of sedimentary rock (S). An igneous intrusion (I1) has broken through the bottommost layer of rock. A second igneous intrusion (I2) has moved up the fault and pooled on top of the uppermost layer of rock. Which event would be considered the youngest?

Which principle or law of geology states that in a sequence of undeformed sedimentary rocks, each bed is older than the one above?

What term describes an erosional surface bounded above by flat-lying sedimentary rocks and below by igneous or metamorphic rocks?

The fact that sedimentary rocks are almost always deposited in a horizontal position reflects which law or principle of geology?

While working in the field, you encounter an outcrop in which sandstone, shale, and limestone have been intruded by a basaltic dike. You know that the basaltic dike is younger than the sedimentary rock applying which law or principle?

In the field you encounter a sequence of sedimentary rocks that has a dike running through them. A normal fault crosses the entire sequence, cutting off part of the dike near the surface. Which scenario best describes your observations? (All scenarios list events from oldest to youngest.)

A ________ is formed when magma intrudes between existing sedimentary layers.

If a limestone, a shale, and a sandstone are deposited in that order without interruption, which of the following is true?

What scenario requires a geologist to use the principle of cross-cutting relationships?

Which of the following is associated with an erosive surface?

An igneous dike cuts across existing sedimentary layers and erupts at the surface, creating a layer of basalt. The basalt, as well as all the layers below, are then cut by a fault. Which statement is true?

A sandstone contains inclusions of metamorphic rock. An igneous dike cuts both the sandstone and inclusions. List the rocks from youngest to oldest.

If a sequence of sedimentary units is cut by a fault, what does the principle of cross-cutting relationships tell a geologist?

Which of the following describes the principle of original horizontality?

An undeformed sequence of sedimentary rocks is exposed in a large river canyon. Which two principles would be demonstrated by the rocks?

An ingeous dike cuts through limestone, but not through the overlying sandstone. Which of the following statements is most accurate?

What is the best definition of fossil range?

Which of the following characteristics is the most desirable for constraining the relative age of rocks

Which organism from the video is least useful for relative dating?

If a rock contains ten different kinds of fossils, which of the following must be true?

How is the geologic time scale related to the fossil record?

What happens during radioactive decay?

What is the scientific definition of half-life?

Two containers hold the same radioactive isotope. Container A contains 1000 atoms, and container B contains 500 atoms. Which of the following statements about containers A and B is true?

A container hold 100 atoms of an isotope. This isotope has a half-life of 1.5 months. How many total atoms will be in the container after 3 months?

A container holds 100 atoms of an isotope. This isotope has a half-life of 1.5 months. How many atoms of the radioactive isotope will be in the container after 3 months?

How is the atomic number of an atom determined?

Which process is not a common form of natural radioactive decay?

Which material, principle, or process enables a method of numerical dating?

Which is an example of radioactivity that occurs when a neutron is converted to a proton and an electron is emitted from the nucleus?

After four half-lives of decay, what is the ratio of radioactive parent isotope to stable daughter isotope?

A radioactive element undergoes decay via the loss of two alpha particles to form a stable daughter isotope. Following the decay, what would the atomic number of this newly created stable isotope be?

Which represents the correct sequence from oldest to most recent or current eras on the Geologic Time Scale?

Which eon translates to "visible life" from the Greek?

Which is the shortest interval of geologic time?

The subdivisions of the Geologic Time Scale were based on which criteria or characteristics?

Which event is generally used to indicate the beginning of the Phanerozoic eon?

While working in the field, you find some sedimentary rocks that include hundreds of fossils of crinoids, numerous brachiopods, and a few trilobites. Realizing that these ancient organisms are some of the first with hard parts, and (when taken as a group) are not very similar to animal communities living today, in which unit of geologic time would you place these rocks?