Geology- Chapter 10 – Flashcards

A corpse with flesh intact, found in the Alps in 1991, was dated by the carbon-14 method and showed a parent-daughter isotope ratio of approximately 1:1, with slightly more parent material than daughter material. The half-life of carbon-14 is 5,730 years. Which of the following statements is TRUE? A. Since the body was still organic and had not been petrified, it was inappropriate to use the carbon-14 process. B. The age could logically be 6,730 years. C. The age could logically be 5,300 years. D. The age could logically be 6,000 years.

A radioactive isotope of the element potassium decays to produce argon. If the ratio of argon to potassium is found to be 7:1, how many half-lives have occurred? A. 1 half-life B. 3 half-lives C. 7 half-lives D. 8 half-lives

An area of slightly dipping sedimentary rock layers has large inclusions and is intruded by an igneous dike. Apply the basic principles for determining relative ages and identify the FALSE statement. A. The sedimentary layers started out lying flat B. The oldest sedimentary layer is the bottom layer. C. The igneous intrusion "baked" (metamorphosed) the sedimentary rock it touched. D. The dike is older than the sedimentary rock layers it cuts across.

Charcoal (burned wood) that was used to make prehistoric drawings on cave walls in France was scraped off and analyzed. The results were 4 mg carbon-14 (parent isotope) and 60 mg nitrogen (daughter isotope). The half-life of carbon-14 is 5,730 years. How old are the cave drawings? A. 11,460 years B. 17,190 years C. 22,920 years D. The sample is too old to be analyzed by carbon dating.

Choose the proper listing of names to fit the following three descriptions- Age of Mammals, Age of Dinosaurs, and longest geologic time period A. Mesozoic, Cenozoic, Paleozoic B. Cenozoic, Hadean, Paleozoic C. Mesozoic, Cenozoic, Proterozoic D. Cenozoic, Mesozoic, Precambrian

Geologists estimate that the age of the Earth is 4.54 billion years old, based on A. radiometric age dates on rocks from the Canadian craton. B. isotopic dating of meteorites thought to be from primitive solids of the early Solar System C. relative age dates on clastic zircons from Australia D. age estimates of Moon rocks.

Identify the FALSE statement. Radiometric dating A. can begin only when the isotopes cool enough to lock into the crystal lattice. B. can be used only if there is some uranium present in the rock. C. of sedimentary rock dates the time of crystallization of the sedimentary minerals, not the time of sedimentary rock formation D. of metamorphic rock tells when the high temperatures of metamorphism cooled below the closure temperatures of the minerals involved.

Identify the FALSE statement. William Smith's observations A. were made around 1800 in fresh exposures of sedimentary bedrock in the English countryside. B. recognized that groups of fossil species (fossil assemblages) occurred in limited intervals of strata. C. noted that a fossil species could disappear then reappear in much younger strata. D. lead to the principle of fossil succession.

If you equate all Earth history to one calendar year, the history of our species (Homo sapiens) would occupy A. the week from Christmas to New Year's Eve B. from December 15 to New Year's Eve. C. from December 31 at 3 p.m. to New Year's Eve D. the last hour before midnight on New Year's Eve

In 1815, William Smith correlated strata from many locations and plotted it on paper to show the spatial distribution of rock units on Earth's surface. This document was the first modern: A. geologic column B. geologic map C. stratigraphic column D. geologic time scale

The boundary surface between two stratigraphic formations is called a A. key bed. B. marker bed C. contact D. nonconformity

Uniformitarianism A. means Earth's surface—its oceans, continents, and atmosphere—have always been the same and always will be the same B. is an outdated theory that states catastrophes like major volcanic eruptions no longer happen. C. is illustrated by scientists' seeing pillow lava form only underwater, then theorizing that pillow lava found high in the mountains today did nevertheless form underwater. D. means neither the scientific past nor the future should be predicted because physical laws change over time

What type of unconformity forms when sedimentary rocks overlie either igneous or metamorphic rocks? A. nonconformity B. angular unconformity C. disconformity D. baked contact

Which of the following accurately ranks the subdivisions of geologic time in order from largest to smallest? A. eon, era, period, epoch B. era, eon, epoch, period C. epoch, period, eon, era D. period, era, eon, epoch

Which of the following is NOT a method to determine numerical age? A. carbon-14 dating B. radioactive decay of uranium to lead C. analyzing growth ring patterns in trees D. cross-cutting relations

Which of the following is TRUE? A. Geologists learned how to determine numerical age long before they could determine relative age. B. Specifying the age of one feature with respect to another is called its relative age. C. Saying that a fossil is 4 million years old reports its relative age. D. Specifying the date on which an event took place is an example of relative age

Which of the following methods of determining the age of materials is a radiometric dating technique? A. rhythmic layering of snow layers in glacial ice B. dendrochronology (tree rings) C. seasonal changes in growth rings in shelled organisms D. carbon dating

Which of the following shows the four time divisions listed from oldest to youngest? A. Precambrian, Mesozoic, Archean, Cenozoic B. Precambrian, Paleozoic, Mesozoic, Cenozoic C. Phanerozoic, Precambrian, Mesozoic, Cenozoic D. Hadean, Cenozoic, Mesozoic, Proterozoic

Which of the following statements is FALSE? A. Scientists can date any radioactive material back only three half-lives; after this there's not enough parent material left to measure. B. Carbon-14 dating is used to date organisms, not minerals. C. Isotopic dating relies on the parent-daughter ratio. D. The "radiometric clock" starts when a radioactive mineral cools below its closure temperature.

Which of the following statements is FALSE? A. A formation is the name of a rock layer identified by such factors as rock type and approximate geologic age B. An unconformity is a break in the rock record that indicates the area was underwater for millions of years. C. The generally accepted age of Earth is 4.54 billion years. D. Varieties of an element that differ only in the number of neutrons are called isotopes.

Which of the following statements is FALSE? The principle of A. superposition says in a sequence of sedimentary beds, the youngest is on top. B. original continuity says sedimentary layers began as continuous expanses of sediment C. inclusions says rock containing inclusions is older than the inclusions D. cross-cutting relations says the feature doing the cutting is younger than the feature it cuts.