Transcript Document
The Marine Environment Ocea 101 Raphael Kudela Beginnings of the Universe, Earth, and Life The Universe and Solar System Dimensions and distances Our planets Earth’s Composition Structure of the Earth Types of rocks Relative versus Absolute Dating Geological History Where did the water and salts come from? Origins of Life Cold versus Hot autotrophic, heterotrophic, chemotrophic The Universe and Galaxies Still expanding… Universe Contains ~1020 stars Milky Way is about 15 billion years old (byp), and is a Spiral galaxy Our galaxy contains about 100 billion stars ~100,000 light years across Structure of the Early Universe Turquoise or Beige? Glazebrook and Baldry (2002) calculated that the universe was Turquoise…. But it turns out it’s really Beige. The Solar System ~ 5 byp old Condensed from a stellar supernova--it started as a hot, rotating cloud of gases The Solar System As the solar system condensed, it formed planets…those that are close to the sun lost their atmospheres Proto-Earth formed ~4.8 byp 100,000x larger, and 500x heavier Moon formed by an impact with something the size of Mars Earth is far enough away from the sun to keep its atmosphere, close enough not to freeze The Earth’s Composition 3 Layers: Core (Fe, Ni) Mantle (Fe, Mg, Si, O) Crust (aluminosilicates) 3 Types of Rock: Igneous Sedimentary Metamorphic Oceanic Basins are formed of basalts, continents are mostly granitic Dating Rocks Relative Dating Early 19th Century Correlate rock strata with fossils Absolute Dating Curies discovered radiation Almost all rocks have radio-isotopes If you know t1/2, can calculate exact date Radioisotope Radon-222 Strontium-90 Radium-226 Plutonium-239 Uranium-235 Half-life 4 days 28 years 1602 years 24 400 years 700 000 000 years Carbon-14 Phosphorous-32 Tritium (H-3) Americium-241 Nitrogen-13 5730 years 14.3 days 12.3 years 432 years 9.96 minutes Radioactive Decay Functions Pt=P0 -lt e P= Parent Isotope D= Daughter Isotope t= Time l= Radioactive decay function t1/2= half-life Geological History Initially ,there was no atmosphere, no ocean (too hot), no oxygen! ~4byp, oceans formed Outgassing of volcanoes, or “snow-balls”? Water allows chemical weathering of rocks Heavy elements (Na, Ca, K, Si, Mg, Fe) appear to have come from rocks (dissolution) Excess volatiles (Cl, S, C, N) had to come from volcanoes! Hydrologic Cycle Scientific Hypotheses (post-Beagle) Edward Forbes--The “azoic hypothesis” Ross Brothers--Deep sea life at the poles, and the “emergence hypothesis” Darwin: Natural selection and evolution 1857: T.H. Huxley describes “Bathybius haeckllii” Origins of Life Development of amino and nucleic acids 1st organisms were probably simply “heterotrophs” ~3.85 byp ~3.5 byp, first autotrophs, bluegreen algae (or cyanobacteria) arose…adapted to an oxygen rich atmosphere Endosymbiosis Hypothesis First proposed by Lynne Margulis (1974) QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. We are symbionts on a symbiotic planet and if we care to, we will find symbiosis everywhere” -- Lynne Margulis Evolution of Photosynthesis • Photosynthesis evolved in the absence of oxygen (a very reducing atmosphere) • It evolved independently in a number of bacterial organisms • It is responsible for all present-day oxygen in the atmosphere