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2.4: Essential Concepts of Historical Geology and Evolution

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    9771
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    Essential Concepts of Historical Geology & Evolution

    The geologic time scale is a systematic and chronological organization of time related to the history of the Earth and Universe used by scientists (geologists, paleontologists, astronomers) to describe the timing and relationships between events that have occurred (see Figure 2.1).

    Paleontology is the scientific study of life forms existing in former geologic periods, as represented by their fossils; the science involves reconstructing the physical characteristics of organisms, life habits, and the environments where they lived (paleoecology).

    A fossil is a remnant or trace of an organism of a some earlier geologic age, such as a skeleton or leaf imprint, embedded and preserved in sedimentary deposits. Few things living today will survive to become fossils (see table to right on how fossils form).

    The term fossil record is used by geologists and paleontologists (scientists who study paleontology) to refer to the total number of fossils that have been discovered, as well as to the information derived from them. Many species that we see today do not get a chance to be preserved as fossils, but we can still learn about them by comparing them to fossils that have been found and properly recorded.

    Fossilization is the processes that turn plant or animal remains eventually to stone.

    A trace fossil is a fossil impression of a footprint, trail, burrow, or other trace of an animal rather than of the animal itself.

    Review of how fossils form
    (or how they survived destruction)

    After an organism dies, its remains must:

    1.
    survive being eaten (at least partially eaten).

    2. must survive transport to site of preservation.

    3. survive burial in sediments or volcanic materials.

    4. survive bioturbation (being chewed up underground by burrowing organisms).

    5. survive microbial decay.

    6. survive compaction with burial.

    7. survive chemical changes associated with lithification.

    8. survive uplift, weathering and erosional exposure.

    9. be discovered and identified.

    10. be researched, reported, and curated to be useful.