Chapter 101. james hutton, the “father of geology,” put forth the principle of _____. a. superposition b. original continuity c. original horizontality d. uniformitarianism2. as understood by modern geologists, the principle of uniformitarianism implies that ________. .a. the earth has always had the same basic appearance that it has today, which the distributions of ocean basins and continents identical to what we see todayb. igneous, metamorphic, and sedimentary rocks are uniformly mixed throughout the crust of the earthc. physical processes observed today (such as erosion and volcanic eruption) havebeen active in the past and are responsible for the geologic history we see preserved in therock recordd. physical processes observed today (such as erosion and volcanic eruption) havebeen occurring throughout earth history at constant rates; for example, no eruption in geologic time would have been greater than the 1815 tambora eruption.3. in an undisturbed sequence of sedimentary rocks, younger layers overlay older layers, according to the principle of . a. superposition b. original continuity c. original horizontality d. uniformitarianism4. if the lithology and fossil content of two bodies of rock on opposite sides of a canyon are identical, then these remaining outcrops were likely physically connected at one time and formed part of an extensive,sheet-like layer of rock. This idea summarizes the principle of ____.a. superpositionb. original continuityc. original horizontalityd. uniformitarianism5. which of the following geologic principles is a direct result of gravity?a. baked contactsb. cross-cutting relationshipsc. original horizontalityd. inclusions6. relative ages expressed on the geologic time scale primarily resulted from the study of _______.a. fossil content and spatial relationships among igneous rocksb. fossil content and spatial relationships among sedimentary rocksc. radiometric dating of igneous rocksd. radiometric dating of sedimentary rocks7. numerical ages for boundaries between time units on thegeologic time scale primarilyresulted from the study of ______, in conjunction with relative age data..a. fossil content and spatial relationships among igneous rocksb. fossil content and spatial relationships among sedimentary rocksc. radiometric dating of igneous rocksd. radiometric dating of sedimentary rocks8. within the world’s sedimentary rocks, fossils ____.a. are rarely, if ever, foundb. are randomly distributedc. occur in an ordered sequence.9. if horizontalsedimentary strata overlie tilted strata (and no fault is present), the surfacebetween the horizontal and tilted strata must be a(n) ____.a. conformable sedimentary contactb. angular unconformityc. disconformityd. nonconformity10. the surfacebelow sedimentary rocks that overlie igneous or metamorphic rocks is termed a(n) _____.a. disconformityb. angular unconformityc. nonconformity11. buried erosional surfaces between parallel sedimentary strata are termed ___.a. disconformitiesb. angular unconformitiesc. nonconformities12. which method of correlation is more reliable for determining relative ages of rock units over broa area?a. lithologic correlationb. fossil correlation13. two atoms of a single element that differ in number of neutrons are said to represent two distinct _______ of that element.a. isomersb. isotopesc. isothermsd. atomic species14. which of the following is always the same for multiple isotopes of a single element?a. atomic numberb. atomic mass numberc. tendency to decay radioactivelyd. none of the above15. which of the following always varies among multiple isotopes of a single element?a. atomic numberb. atomic mass numberc. tendency to decay radioactivelyd. none of the above16. which proportion of a radioactive isotopeis expected to remain in an unaltered (unreacted) state after the passage of three half-lives?a. one-thirdb. three-halvesc. one-eighthd. one-sixth17. in an unweathered sample of igneous rock, the ratio of an unstable isotope to its stabledaughter isotope is 1/15. If no daughters were present at the time the rock cooled,and the half-life of thereaction is 50 million years, how old is the rock?a. 200 millionyearsb. 400 millionyearsc. 750 millionyearsd. none of the above18. in an unweathered sample of detrital sedimentary rock,the ratio of an unstable isotopeto its stable daughter isotope is 1/15. If no daughters were present at the time the rock cooled, and the half-life of the reaction is 50 million years, how old is the rock?a. 200 millionyears b. 400 millionyearsc. 750 millionyearsd. none of the above19. radiometric dates appliedto sedimentaryrocks produce ages that are ___.a. just as accurate as when the technique is appliedto igneous rocks.b. too young (postdate sedimentary deposition)c. too old (predate sedimentary deposition)20. which statement best summarizesthe development of the geologic time scale?a. numerical ages for rocks were known well before the relative sequence of sedimentary layers was established.b. relative ages for sedimentary strata were known well before accurate numericaldates for these rocks could be provided.c. names of relative ages (such as silurian) and accurate numerical dates for theseages appeared at about the same time.21. radioactive decay provides the internal heat of the earth.a. trueb. false22. if the numerical ages of two formations are known, then the relative age of each with respect to one another can be inferred.a. trueb. false23. if the relative age of two formations (with respect to one another) is known, then the numerical ages for each formation can be inferred.a. trueb. false24. in the area immediately surrounding an igneous intrusion, a host limestone is locally metamorphosed to produce marble. Which of the following statements is correct?a. the intrusiveigneous rock must be older than the limestoneb. the limestone must be older than the marblec. the marble must be older than the intrusive rock.d. the relative ages of the three units cannot be determined with the information given.25. the earth isapproximately 4.6 billion years old.a. trueb. false26. the surfaces named contacts #2 and #3 are examples of _____.a. conformable sedimentary contactsb. faultsc. baked contactsd. unconformities27. contact #1 is an example of a(n) ___.a. conformable sedimentary contactsb. faultsc. baked contactsd. unconformities28. the oldest geologic unit in the cross section is the ___.a. graniteb. marblec.