Announcements: none

Lecture notes:
Themes for the exam:
    age of the earth (the dispute over)
    relative dating
    absolute dating
    Unified Geological Time scale
    radiometric dating
    Neptunists/Plutonists
    extinction events
    features of sedimentary rocks

National Parks covered:
    Bryce
    Arches
    Great Basin
    Grand Canyon
    Isle Royale
    Dinosaur
    Florrissant
    ANWR

I. Geologic Time Scale
    A. Know the order of the main titles, the date is the time period, and the main species living there at that time

    B. Know what defines where one division ends and another begins

    C. Precambrian (570 million years)
            1. Vast majority of life is Precambrian
            2. "Time of algae"
            3. Changed over to Paleozoic because of the atmosphere of the earth changed
            4. There are now marine species while before there was mostly abundant oxygen and algae and no life

    D. Paleozoic
            1. Cambrian is the oldest of the Paleozoic time period
            2. "Time of warm ocean life"
            3. Tons of limestone and shellfish
            4. Changed over to Mesozoic because of habitat

    E. Mesozoic (225-65 million years)
            1. "Age of the Dinosaurs"; end of Mesozoic was the end of the dinosaurs
            2. The boundary between Mesozoic and Cenozoic is called the K-T Boundary ("K" stands for Krustaceas and
            "T" stands for Terciary)
            3. This period was considered a major extinction event

    F. Cenozoic (65 million years to present day)
            1. "Age of the mammals"
 
II. Superposition--"being on top of something else"; rocks laying on top of another layer of rocks

III. Nothing lives in andesite, basalt, or granite material therefore you can't find fossils in ingenious rocks

IV. Radioactivity
    A. Finding absolute age of rock
    B. Relative age
            1. Unified Time Scale ("unified" because):
                    a. Uses absolute and relative times
                    b. Uses both igneous and sedimentary rocks

V. Radiometric dating
    A. Some atoms of some elements are unstable when formed; if they're unstable they spontaneously undergo
    fission so they can try and remain stable
            1. This causes two (2) things:
                    a. A release of energy
                    b. Changes the proportions of elements in rocks

            2. Two (2) types of decay systems
                    a. Uranium/lead--drives earth's heat; formation of atomic bombs, nuclear reactor
                    b. Potassium/argon--diffusion, decays to argon gas

VI. Neptunists--having to do with "Great Flood"; Werner's interpretation was that granites, igneous rocks predated
the "Great Flood" and all the other rocks came after

VII. Plutonists--originated far earlier than Neptunism; said the earth had a lot of heat inside; James Hutton (first to speak
of Uniformitarianism) said the earth does have internal heat

VIII. Charles Darwin--his first calculation of the age of the earth was 300 million years old; his next estimate was about 96 million years old

IX. Lord Kelvin--his estimate for the age of the earth was about 98 million years old; Kelvin failed to consider that the earth does, in fact, give off it's own heat internally; said the earth formed through the accretion of meteorites