14Relative TimeThe geologic time scale provides a relative measure of time. The geologic time scaleis based on the fossil record.Divisions of timeEonsErasPeriodsEpochsMajor DivisionsHadeanCrytozoic EonPhanerozoic Eon
17Subdivisions of the Cryptozoic Archean EraProterozoic EraSubdivisions of the PhanerozoicPaleozoic EraCambrian PeriodOrdovician PeriodSilurian PeriodDevonian PeriodCarboniferous PeriodPermian PeriodMesozoic EraTriassic PeriodJurassic PeriodCretaceous Period
19Absolute TimeThere has been a long debate over the age of the Earth. Theage of the earth is key to evaluating geologic and biologic processes.Measuring the age of the earth ; physical methods (rate of deposition,alt concentration etc.), radioactive dating (K-Ar, U-Pb, Th-Pb)Age of EarthOldest earth rocks are 3.8 billion years old.Meteorites on earth are generally around 4.6 billion years old.Moon rocks are between 4.6 and 3 billion years old.Age of the earth is thought to be 4.6 billion years old.
28Geologic PrinciplesThree principles form the basis for stratigraphic and paleontologic studies.These are principle, not laws. There are limitations. Development of thegeologic time scale relied heavily on these principles and their limitations.
29กฎและแนวคิดสำคัญของธรณีวิทยา (Geologic Principles) 1. Superposition- original horizontality,- lateral continuity2. Uniformitarianism- The present is the key to the past.- Modern processes operating over long periods of timeproduced the earth features.3. Faunal succession- Fossil or groups of fossils occur in distinct intervals of rock.- Correlation is possible based on fossil.- Subdivision of the rock record is possible based on fossil assemblage.