Earth Science, 12e (Tarbuck/Lutgens) · Web viewChapter 11: Geologic Time 1) An unconformity is a buried _____. A) fault or fracture with older rocks above and younger rocks below
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Earth Science, 12e (Tarbuck/Lutgens)Chapter 11: Geologic Time
1)
An unconformity is a buried ________. A)
fault or fracture with older rocks above and younger rocks below B)
surface of erosion separating younger strata above from older strata below C)
fault or fracture with younger strata above and older strata below D)
surface of erosion with older strata above and younger strata below Answer:
B Diff: 1
2)
Which of the following best characterizes an angular unconformity? A)
Tilted strata lie below the unconformity; bedding in younger strata above is parallel to the unconformity.
B)
Horizontal lava flows lie below the unconformity and horizontal, sedimentary strata lie above.
C)
The discordant boundary between older strata and an intrusive body of granite. D)
Tilted strata lie below the unconformity with loose, unconsolidated soil above. Answer:
The subdivision of the geologic time scale that represents the longest time span is called a(n) ________.
A)
epoch B)
era C)
period D)
eon Answer:
D Diff: 1
7)
The ratio of parent to daughter isotopes in a radioactive decay process is 0.40. How many half-lives have elapsed since the material was 100% parent atoms?
A)
less than l B)
more than 3 C)
between l and 2 D)
between 2 and 3 Answer:
C Diff: 2
8)
Consider the names of the eras in the geologic time scale. What is meant by "zoic"?
What fundamental concept states that in a horizontal sequence of conformable sedimentary strata, each higher bed is younger than the bed below it?
A)
law of original correlation B)
theory of correlative deposition C)
law of superposition D)
theory of superstition Answer:
C Diff: 1
12)
Which of the following refers to the investigative process by which geologists identify and match sedimentary strata and other rocks of the same ages in different areas?
A)
super matching B)
correlation C)
strata indexing D)
cross-access dating Answer:
B Diff: 1
13)
The ________ is the idea or concept that ancient life forms succeeded each other in a definite, evolutionary pattern and that the contained assemblage of fossils can determine
Which of the following describes radioactive decay by beta particle emission? A)
The atomic number of the daughter isotope is one more than the parent; the mass numbers are the same.
B)
The mass number of the daughter isotope is one more than the parent, and both isotopes have the same atomic number.
C)
The daughter isotope has an atomic number two less than the parent and a mass number four less.
D)
The daughter isotope has an atomic number one less than the parent and a mass number two less.
Answer:
A Diff: 1
20)
The half-life of carbon-14 is about 6000 years. Assume that a sample of charcoal formed by burning of living wood 15,000 years ago. How much of the original carbon-14 would remain today?
Visualize five horizontal sedimentary strata exposed in a cliff or canyon wall identified by consecutive numbers, 1 being the lowest bed and 5 being the highest. Which of the following statements concerning the strata are true?
A)
Bed 5 is the oldest. B)
Beds l and 3 are older than bed 4. C)
Bed 4 is older than bed 2. D)
Bed 3 is older than beds 2 and 4. Answer:
B Diff: 2
22)
Which of the following denotes the divisions of the geologic time scale in correct order of decreasing lengths of time beginning with the longest time interval and ending with the shortest?
Who made the first clear statement of the law of superposition? When? A)
John Wesley Powell, nineteenth century B)
William Smith, eighteenth century C)
John Stuart Priestly, nineteenth century D)
Nicolaus Steno, seventeenth century Answer:
D Diff: 1
27)
Sandstone strata and a mass of granite are observed to be in contact. Which of the following statements is correct geologically?
A)
The sandstone is younger if the granite contains sandstone inclusions. B)
The sandstone is younger if it shows evidence of contact metamorphism. C)
The granite is older if the sandstone contains pebbles of the granite. D)
The granite is older if it contains inclusions of sandstone. Answer:
C Diff: 2
28)
Assume that you have just examined several flat-lying sedimentary layers. After much study you determine that there is a considerable span of time for which no sedimentary rock layer exists at this site. You have just discovered a(n) ________.
Word Analysis. Examine the words and/or phrases for each question below and determine the relationship among the majority of words/phrases. Choose the option which does not fit the pattern.
31)
A. electron capture B. alpha emission C. delta capture D. beta emission Answer:
C Diff: 2
32)
A. Paleozoic B. Mesozoic C. Phanerozoic D. Cenozoic Answer:
B Diff: 1
33)
A. superposition B. correlation C. original horizontality D. inclusions Answer:
B Diff: 1
34)
A. Uranium-238 B. Rubidium-87 C. Carbon-14 D. Potassium-40 Answer:
C Diff: 1
35)
The geologic time scale was devised before numerical dating using radioactivity was invented.
Answer:
TRUE Diff: 1
36)
Numerical age dates based on radioactivity are very important for studying Precambrian geologic history because fossils are rare or absent.
Correlation of rock units between continents or widely separated areas is accomplished by using physical features such as color, texture, and thickness of units.
Answer:
FALSE Diff: 1
50)
Rapid burial and possession of hard parts are necessary conditions for the preservation of plant or animal remains as fossils.
Answer:
TRUE Diff: 1
51)
The Paleozoic is the era of "ancient life." Answer:
TRUE Diff: 1
52)
All of geologic time prior to the beginning of the Paleozoic era is termed the Phanerozoic eon.
What is the name of a Phanerozoic era that means ancient life? Answer:
Paleozoic Diff: 1
66)
The remains or traces of prehistoric life are called ________. Answer:
fossils Diff: 1
67)
We now live in the ________ era. Answer:
Cenozoic Diff: 1
68)
In an undeformed sequence of sedimentary rocks, each bed is older than the one above and younger than the one below. The preceding is a statement of the law of ________.
Answer:
superposition Diff: 1
69)
All of geologic time prior to the beginning of the Paleozoic era is commonly referred to as the ________.
Answer:
Precambrian Diff: 1
70)
An unconformity in which the strata on either side are essentially parallel is termed a(n) ________.
Critical Thinking and Discussion. Use complete sentences, correct spelling, and the information presented in Chapter 11 to answer the questions below.
71)
Compare and contrast relative age dating with radiometric age dating. What is a limitation (if any) of each?
Diff: 2
72)
In a given area where you have little knowledge of the local geology (rocks types, fossils, etc.), what type of unconformity would be the most difficult to recognize in an exposed sequence of rocks? Why?
Diff: 2
73)
You are asked to interpret the geologic history of a county in California where the geology is quite complex. Aside from visiting various sites in the county for observing geologic sites firsthand, you are permitted to request five different pieces of information or data to aid in your interpretation. List the five that you would choose and explain why each is important for your study.
On the blank provided beside each geologic cross section below, write the name of the specific type of unconformity that is labeled with an arrow. The v-pattern indicates igneous rocks. All other patterns are different types of sedimentary rocks.
(a) In the chart of radioactive decay shown below, how many half-lives have elapsed by time (a)?_______________(b) How many half-lives have elapsed by time (b)? _______________
(a) Which feature is the youngest? ______________________________(b) Which feature is the oldest? ______________________________
Answer:
(a) h (b) t Diff: 2
77)
Examine the illustration below (a cross section through the Earth as you might observe on the wall of a quarry or a road cut). Give two reasons why the granite must be older than the sedimentary layers.
Answer:
The sedimentary layers are deposited on top of the granite (principle of superposition). Also, inclusions of the granite in the sedimentary layer indicate that the granite is older using the principle of inclusions.