GLACIAL PROCESSES

GLACIAL PROCESSES - GLACIAL PROCESSES & LANDSCAPES...

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** Climate Change: * climate & weather don't stay the same, they change day to day, year to year, millennium to millennium * climate change is a significant change in these averages over hundreds of thousands of years * climate system ; the interaction of all spheres (atmosphere, lithosphere, biosphere, hydrosphere) * when change occurs in one sphere, it usually affects the other spheres * Evidence of climate change: E oxygen isotope analysis of ice cores from Greenland & Antarctica and sea floor sediments : the ratio of 18 O to 16 O in calcareous marine microfauna & from ice cores can indicate glacial vs. inter-glacial periods * 18 O doesn’t evaporate out of the seawater as easily as 16 O under colder water conditions, thus more 18 O will be left in 3 when it recrystallizes to form shell material * So, when Ts are colder the ratio:
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in ice cores is more 16O than 18O than under warmer conditions in seashells is more 18O than 16O than under warmer conditions i tree rings : indicate dry vs. wet periods palynology (study of fossil pollens) : indicate wet vs dry & cool vs warm periods by type of plant pollen geologic formations (coal deposits) ( human historical records h * Climate change theories: * Non-human Induced Causes: Plate tectonics: move into or out of a climate type as continents move Volcanic activity: increased amount of dust & ash in atmosphere affects T°'s Astronomical or Milankovitch theory Eccentricity : changing the shape of Earth’s orbit; average period of about 95,800 yrs; varies solar receipt Obliquity : changes in angle or tilt of Earth’s axis; varies from 21.8 degrees to 24.4 degrees on a cycle of about 41,000 yrs; changes levels of solar radiation between summer and winter
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Axial Precession : wobbling of the Earth’s axis, which changes the alignment of the axis with the stars in space; wobbling describes a circle, returning to the same point about every
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GLACIAL PROCESSES - GLACIAL PROCESSES & LANDSCAPES...

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