14. Relative Time The geologic time scale provides a relative measure of time. The geologic time scale is based on the fossil record. Divisions of time Eons Eras Periods Epochs Major Divisions Hadean Crytozoic Eon Phanerozoic Eon
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17. Subdivisions of the Cryptozoic Archean Era Proterozoic Era Subdivisions of the Phanerozoic Paleozoic Era Cambrian Period Ordovician Period Silurian Period Devonian Period Carboniferous Period Permian Period Mesozoic Era Triassic Period Jurassic Period Cretaceous Period
18. Cenozoic Era Tertiary Period Paleocene Epoch Eocene Epoch Oligocene Epoch Miocene Epoch Pliocene Epoch Quaternary Period Pleistocene Epoch Holocene (Recent) Epoch
19. Absolute Time There has been a long debate over the age of the Earth. The age 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 Earth Oldest 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.
28. Geologic Principles Three principles form the basis for stratigraphic and paleontologic studies. These are principle, not laws. There are limitations. Development of the geologic time scale relied heavily on these principles and their limitations.
29. 1. Superposition - original horizontality, - lateral continuity 2. Uniformitarianism - The present is the key to the past. - Modern processes operating over long periods of time produced 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. กฎและแนวคิดสำคัญของธรณีวิทยา (Geologic Principles)