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An unconformity is a buried ________
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Which of the following best characterizes an angular unconformity
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Quiz 7 Geology
| Question | Answer |
|---|---|
| An unconformity is a buried ________ | surface of erosion separating younger strata above from older strata below |
| Which of the following best characterizes an angular unconformity | Tilted strata lie below the unconformity; bedding in younger strata above is parallel to the unconformity. |
| In the late 1700s James Hutton published his important work titled ________ | Theory of the Earth |
| Which of the following is not a very long-lived, radioactive isotope? | C-14 |
| Catastrophism _____ | was a philosophy that was first expounded by the early Greeks |
| The subdivision of the geologic time scale that represents the longest time span is called a(n) ________ | eon |
| 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 | between l and 2 |
| Consider the names of the eras in the geologic time scale. What is meant by "zoic" | life; living things |
| Who is credited with formulating the doctrine of uniformitarianism | Hutton |
| Which of the following geologic observations would not bear directly on working out the sequence of geologic events in an area | the feldspar and quartz contents of a granite |
| What fundamental concept states that in a horizontal sequence of conformable sedimentary strata, each higher bed is younger than the bed below it | law of superposition |
| 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 | correlation |
| 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 geologic ages of strata | principle of fossil (faunal) succession |
| Which of the following is an essential characteristic of an index fossil | The organism only lived for a short period of geologic time. |
| By applying the law of superposition ________ dates can be determined. | relative |
| The era of "ancient life" is the ________ era | Paleozoic |
| About 88 percent of geologic time is represented by the time span called the ________. | Precambian |
| What is the age of the Earth accepted by most scientists today | 4.5 billion years |
| Which of the following describes radioactive decay by beta particle emission? | The atomic number of the daughter isotope is one more than the parent; the mass numbers are the same. |
| 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? | between one-fourth and one-eighth |
| 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? | Beds l and 3 are older than bed 4. |
| 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 | eon, era, period, epoch |
| Assume that man's recorded history can be stretched back to 4600 years before the present. This is approximately what fraction of geologic time? | one millionth |
| When a radioactive isotope decays by electron capture, the electron _______ | combines with a proton in the nucleus; the atomic number of the daughter is one less than the parent |
| ________ is an erosional contact between tilted, older strata below and horizontal, younger strata above. | An angular unconformity |
| Who made the first clear statement of the law of superposition? When? | Nicolaus Steno, seventeenth century |
| Sandstone strata and a mass of granite are observed to be in contact. Which of the following statements is correct geologically | The granite is older if the sandstone contains pebbles of the granite. |
| 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) ________ | disconformity |
| A worm would stand a poor chance of being fossilized because ______ | worms have no hard parts |
| The era known as the "age of mammals" is the ________. | Cenozoic |
| electron capture - alpha emission - delta capture - beta emission | delta capture |
| Paleozoic - Mesozoic - Phanerozoic - Cenozoic | Phanerozoic |
| superposition - correlation - original horizontality - inclusions | correlation |
| Uranium 238 - rubidium 87 - carbon 14 - potassium 40 | carbon 14 |
| The geologic time scale was devised before numerical dating using radioactivity was invented | T |
| Numerical age dates based on radioactivity are very important for studying Precambrian geologic history because fossils are rare or absent | T |
| The term Mesozoic refers to life forms intermediate in complexity between early and much later, more modern-looking life forms | T |
| Most sedimentary rocks are readily dated by radiometric methods. | F |
| After three half-lives, one-ninth of an original, radioactive parent isotope remains and eight-ninths has decayed into the daughter isotope | F |
| A disconformity is an erosional unconformity with parallel beds or strata above and below | T |
| Phanerozoic, marine, sedimentary strata of the same age on different continents can usually be correlated by their fossil assemblages | T |
| The radioactive isotope, potassium-40, has argon-40 as a daughter product | T |
| The term Paleozoic describes the era of ancient life forms | T |
| Pebbles of granite in sandstone and conglomerate resting on the granite suggest that the granite intruded the sedimentary beds | F |
| Radiometric dating means placing events in their proper sequence | F |
| The percentage of radioactive atoms that decay during one half-life is always the same. | T |
| An unconformity involving older metamorphic rocks and younger sedimentary strata is termed a nonconformity. | T |
| Strata above an angular unconformity were tilted before the older strata were eroded. | F |
| Correlation of rock units between continents or widely separated areas is accomplished by using physical features such as color, texture, and thickness of units. | F |
| Rapid burial and possession of hard parts are necessary conditions for the preservation of plant or animal remains as fossils. | T |
| The Paleozoic is the era of "ancient life." | T |
| All of geologic time prior to the beginning of the Paleozoic era is termed the Phanerozoic eon. | F |
| When a beta particle is emitted, the mass number of the isotope remains unchanged. | T |
| After two half-lives there is no longer any of the original radioactive material remaining. | F |
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