Part Two II › Division IV IV › Section 242 242

The Interpretation of the Geologic Record

Subject Outline

AThe stratigraphic interpretation of the geologic record
- 1The layered rocks of the Earth's crust and their depositional environments: the nature of the rock record [see also 214.B.2.]
  - aClastic sedimentary rocks
  - bCarbonate rocks
  - cVolcanic rocks
  - dCyclic deposits: cyclothems, varved deposits
- 2Stratigraphic classifications and their historical development: criteria for the correlation of layered deposits
  - aThe principle of uniformitarianism
  - bThe principle of superposition of strata
  - cThe idea of a fossil succession
  - dThe facies concept
  - eThe stage concept
  - fThe recognition of zones
  - gRadiometric dating [see D.2., below]
- 3Stratigraphic nomenclature in theory and practice
  - aStratigraphic terminology and its standardization
  - bStratigraphic boundary problems
  - cSpecial stratigraphic terminologies and divisions
BThe paleontological interpretation of the geologic record
- 1The nature of fossils and fossilization processes
- 2The fossil record
  - aPrecambrian life: the Proterozoic fossil record
    - iThe origin of life [see 312.A.]
    - iiPrecambrian protists, plants, and animals: the Gunflint Chert deposits, Ediacara fauna, and other remains
  - bPost-Precambrian life: the Phanerozoic fossil record [see also 243 and 313]
    - iFossil plants
    - iiFossil protists
    - iiiFossil sponges
    - ivFossil cnidarians (e.g., corals)
    - vFossil mollusks (e.g., ammonoids)
    - viConodonts
    - viiBryozoans
    - viiiBrachiopods
    - ixFossil arthropods (e.g., trilobites)
    - xFossil echinoderms (e.g., sea lilies); graptolites; fossil fish; fossil amphibians; dinosaurs and other fossil reptiles; fossil birds; fossil mammals
- 3The appearance and disappearance (mass extinctions and background extinctions) of species revealed in the fossil record [see also 312.B.]
- 4The paleontological criteria for the correlation of layered rocks
  - aIndex fossils
  - bFaunal and floral assemblages
  - cOrganic microfossils: pollen, spores, tests
CRelative age dating
- 1Application to geologic problems: stratigraphic correlation and the relative geologic time scale [see also 243]
- 2Application to archaeological problems [see 10/41.B.2.b.]
DAbsolute dating
- 1General considerations: the meaning of absolute age, requirements for absolute dating, the rate of record accumulation
- 2Radiometric dating [see also 723.G.8.]
  - aRadioactivity and radioactive decay [see 112.C.]
  - bPrinciples of radiometric dating
  - cDefinition of time zero, sources of error in radiometric dating
  - dDating methods
- 3Non-radiometric dating: biological and geologic processes as absolute chronometers
- 4Applications of absolute dating
  - aThe absolute geologic time scale
  - bDetermination of the age of the Earth and the ages of rocks and meteorites
  - cDetermination of the rates of seafloor spreading
EThe paleogeographical interpretation of the geologic record