o Life on Earth is due to interactions among the Lithosphere Atmosphere

O life on earth is due to interactions among the

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o Life on Earth is due to interactions among the: Lithosphere Atmosphere Hydrosphere Biosphere o The interlinkage of the physical and the biological: Global changes transform or modify both realms. There are many ways to describe changes: Gradual change ,Catastrophic change ,Unidirectional change ,Cyclic change o Unidirectional Changes: evolution of the solid Earth: " Planetesimal accretion " Melting and differentiation Formation of the Moon: " Mars-sized protoplanet collides " Mantle blasted into space " Debris coalesced to form the Moon. Evolution of the atmosphere and oceans: " Volcanic gases created an early atmosphere. CO2, H2O, N2 " Liquid water condensed to form the oceans. " Photosynthetic organisms appeared.O2 becomes a significant component of the atmosphere. Evolution of Life " Life appeared on Earth about 3.8 Ga. " Multicellular organisms appeared in Late Proterozoic and early Phanerozoic. " Life inhabits all regions, within a few km of Earth’s surface. o Physical Cycles: E.g. The supercontinent cycle: " Plate tectonics drives continental movement. " Ocean basins open and close. " Continental landmasses collide and rift apart. " Supercontinents (like Pangaea) have formed several times. E.g. The rock cycle—there are three types of rock: " Igneous—cooled from a Mel " Sedimentary— made of weathered and eroded materials " Metamorphic—rocks altered by heat and pressure One rock type may transform into any other type. " The atoms in rocks are constantly being rearranged. Global Climate Change: Climate studies reveal our past and suggest our future. " Distinguish kinds of climate changes " Establish rates at which these changes occur " Determine the effects on Earth and its inhabitants. Methods of study: " Paleoclimates—investigations of past climatic variation " Computer simulations—modeling past and future changes. H2O, CO2, and CH4 in Earth’s atmosphere absorb thermal energy and reradiate it, warming the lower atmosphere. " This is called the greenhouse effect. o Paleoclimates —past climates are interpreted by datable Earth materials that are climate-sensitive. E.g. Stratigraphic records—sequences of rock strata Depositional environments are often climate-sensitive. Glacial tills—cold and continental ,Coral reef— tropical marine o Historical records are useful in the reconstruction of past climate change. Written documents Archaeological evidence Paintings Crop records etc. o Long-Term Climate Change: Earth’s climate history has been largely deciphered. Greenhouse—warmer climates Icehouse—colder climates There have been at least five major icehouse periods in Earth’s geologic history. What causes long-term climate changes? Complex interactions across the Earth System Plate tectonics modifies the position of continents. Uplift of land surfaces influences atmospheric
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circulation. Formation of coal and oil removes carbon from atmosphere. Evolution of life affected atmospheric composition.
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  • Fall '09
  • Final, Sedimentary rocks

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