Earth systems

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Ngày đăng: 29/11/2016, 22:44

Today: Lecture Overview Prelude: What is Geology? Nature of the scientific method - Class discussion Overview of Earth Systems Origin of the Earth and Solar System Nebular hypothesis OUR COURSE’S WEBSITE http://geology.asu.edu/jfarmer/g_stu_1.html Note: NO “www”!!! Prelude: “And just what is Geology?” Solid Earth Interior of the Earth is losing heat Primary source of heat: Radioactive decay Heat loss drives convection, based on density differences Hotter stuff is lighter and rises Cooler stuff is denser and sinks Prelude: Earth’s internal structure distinct divisions: crust Oceanic 0-6 km (“young”, < 180 m.y.) Continental 0-34 km (older, up to 3.8 b.y.) mantle Upper 34-670 km Lower 670-2900 km core Outer (liquid) 2900-5160 km Inner (solid) 5160-6370 km Prelude: Plate Tectonics Earth’s dynamic interior and crust Heat loss drives plate tectonics Three types of plate boundaries Prelude: Earth Systems Solid Earth Atmosphere Hydrosphere Cryosphere Biosphere Atmosphere Blanket of gases surrounding the Earth Protection from Sun’s heat & UV rays Weather: due to exchange of energy between Earth’s surface & atmosph between atmosph & outer space Strongly interacts w/ surface Hydrosphere Water portion of Earth Oceans (most prominent) 71% of surface of Earth Streams, lakes, glaciers, underground water Atmosphere Cryosphere Icy portion of Earth’s crust Glaciers Permafrost and ground ice Polar ice caps Frozen polar seas Water is the primary agent of crustal weathering Biosphere Earth’s Ecosystems Earth’s biosphere occupies both the surface and subsurface to depths of a few kilometers Life occupies an extreme range of environments Life strongly interacts with the atmosphere, the hydrosphere and the solid earth to affect their composition and long-term evolution (these interactions are called ecology!) Earth: The Living Planet Most of the biodiversity on our planet is microbial! The Three Domains of Life Boiling mudpot, Yellowstone Some extremes of life Fungi and Plants Plants consume carbon dioxide and produce oxygen via photosynthesis Most of the 21% oxygen in our atmosphere derives from this process! Fungi and and plants form symbioses called Lichens and Mycorrhizae that alter rocks and produce soils Lichens Mycorrhizae Credit: INVAM Credit: Sharnoff Against a constant backdrop of gravity, the atmosphere, hydrosphere and biosphere interact with the rocks of the Earth’s crust to break them down and transport them to depositional basins (e.g the oceans) as sediment The cycle is renewed as internal processes of plate tectonics create new crust and uplift it to form mountain ranges Earth is one of nine planets comprising the Solar System Earth How did the Solar System form? Earth Formation Planets thought to have formed: At same time From same material as the Sun Nebular hypothesis Solar system formed from giant cloud of mostly hydrogen and helium, and a small percentage of heavier elements Nebular Hypothesis: States that the planets of our Solar System were formed by the “accretion” of materials from a cloud of gas and dust called a solar “nebula” Collapse of the nebula under its own gravity formed a rotating disk around a dense, central core of material This core eventually became hot enough to form the Sun [...]... agent of crustal weathering Biosphere Earth s Ecosystems Earth s biosphere occupies both the surface and subsurface to depths of a few kilometers Life occupies an extreme range of environments Life strongly interacts with the atmosphere, the hydrosphere and the solid earth to affect their composition and long-term evolution (these interactions are called ecology!) Earth: The Living Planet Most of the... and biosphere interact with the rocks of the Earth s crust to break them down and transport them to depositional basins (e.g the oceans) as sediment The cycle is renewed as internal processes of plate tectonics create new crust and uplift it to form mountain ranges Earth is one of nine planets comprising the Solar System Earth How did the Solar System form? Earth Formation Planets thought to have formed:
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