geol 1303 chapter 9

What is the source of natural carbon-14? Fusion of hydrogen and helium in the Sun and eruption of solar flares Leakage of radioactive gases from the liquid, outer core Nuclear fission of the heavy, radioactive elements uranium and thorium Cosmic ray collisions and neutron-capture involving atmospheric nitrogen

Cosmic ray collisions and neutron-capture involving atmospheric nitrogen

Which of the following denotes the divisions of the geologic time scale in correct order beginning with the longest time interval and ending with the shortest? Eon, epoch, period, era Eon, era, epoch, period Era, period, epoch, eon Eon, era, period, epoch

Eon, era, period, epoch

The term Paleozoic describes the era prior to the appearance of the earliest fossils in the rock record. True False

False

What fundamental concept states that in a horizontal sequence of conformable sedimentary strata, each higher bed is younger than the bed below it? Principle of original horizontality Principle of lateral continuity Principle of cross-cutting relationships Law of superposition

Law of superposition

The radioactive isotopes uranium-238, uranium-235, and thorium-232 eventually decay to different, stable, daughter isotopes of ___________. Lead Argon Iron Strontium

Lead

Which of the following refers to the process of fossilization where the pores of the original plant or bones of an animal are filled with precipitated mineral matter? Internal and external molds Carbonization Impression Petrification

Petrification

Which of the following refers to the idea or concept that ancient life forms succeed one another in a definite, evolutionary pattern and that the contained assemblage of fossils can determine geologic ages of strata? Principle of faunal succession Law of correlative indexing Law of fossil regression Principle of cross correlation

Principle of faunal succession

With regard to the illustration below, which of the following statements is correct? Sill 'D' was intruded between beds 'C' and 'E' after deposition of 'E' Dike 'F' was emplaced after development of the angular unconformity just below bed 'G' Sill 'D' is younger than dike 'F' Bed 'B' is younger than bed 'C' Tilting of beds 'A' through 'E' occurred after deposition of beds 'G' through 'K'

Sill 'D' was intruded between beds 'C' and 'E' after deposition of 'E'

An unconformity is a buried... Surface of erosion with older strata above and younger strata below Surface of erosion separating younger strata above and older strata below Fault or fracture with younger strata above and older strata below Fault or fracture with older rocks above and younger rocks below

Surface of erosion separating younger strata above and older strata below

Which of the following is an essential characteristic of an index fossil? The fossils occur in deep-water marine sediments, but the organism actually lived on beaches The specific life form spanned a large range of geologic time The organism lived only in specific, geographically restricted, environments such as lakes or estuaries The specific life form only existed for a short range of geologic time

The specific life form only existed for a short range of geologic time

Which of the following best characterizes an angular unconformity? Tilted strata lie above the unconformity with loose, unconsolidated soil below. Tilted strata lie below the unconformity; bedding in younger strata above is parallel to the unconformity. Horizontal lava flows lie below the unconformity and horizontal, sedimentary strata lie above. The discordant boundary between older strata and an intrusive body of granite.

Tilted strata lie below the unconformity; bedding in younger strata above is parallel to the unconformity.

What is the age of the Earth accepted by most scientists today? 6.4 billion years 4.5 million years 4500 billion years 4.5 billion years

4.5 billion years

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? Bed 4 is older than bed 2 Bed 5 is the oldest Beds 1 and 3 are older than bed 4 Bed 3 is older than both beds 2 and 4

Beds 1 and 3 are older than bed 4

The proportion of parent to daughter isotopes in a mineral is 40% parent and 60% daughter. How many half-lives have elapsed since the mineral contained 100% parent atoms? More than 3 Less than 1 Between 1 and 2 Between 2 and 3

Between 1 and 2

A disconformity is an erosional unconformity where sedimentary beds or strata above and below are parallel. True False

True

Most sedimentary rocks are readily dated by radiometric methods. True False

False

The half-life of carbon-14 is about 6000 years. Assume that a sample of charcoal is 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 Between one-half and one-fourth More than one-half Between one-half and one-third

Between one-fourth and one-eighth

Rapid burial and possession of hard parts are necessary conditions for the preservation of plant or animal remains as fossils. True False

True

Which of the following refers to the investigative process by which geologists identify and match sedimentary strata and other rocks in one area with rocks of the same age at different locations? Compaction Absolute dating Correlation Relative dating

Correlation

Which of the following describes radioactive decay by beta particle emission? The daughter isotope has an atomic number two less than the parent and a mass number four less. The daughter isotope has an atomic number one less than the parent and a mass number two less. The atomic number of the daughter isotope is one more than the parent; the mass numbers are the same. The mass number of the daughter isotope is one more than the parent and both isotopes have the same atomic number.

The atomic number of the daughter isotope is one more than the parent; the mass numbers are the same.

Which of the following observations would NOT bear directly on working out the sequence of geologic events in an area? Inclusions of sandstone in a granite pluton The feldspar and quartz contents of a granite A well-exposed basaltic dike cross-cutting sandstone An unconformity between a granite and sandstone

The feldspar and quartz contents of a granite

Sandstone strata and a mass of granite are observed to be in contact. Which of the following statements is correct geologically? The sandstone is younger if it shows evidence of contact metamorphism from the granite The granite is older if the sandstone contains pebbles of the granite The sandstone is younger if the granite contains sandstone inclusions The granite is older if it contains inclusions of sandstone

The granite is older if the sandstone contains pebbles of the granite