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Midterm 1 Chapter Outlines-1,2,9,13,14

Midterm 1 Chapter Outlines-1,2,9,13,14 - Geology 101...

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Geology 101: Midterm 1 Chapters 1, 2, 9, 13, 14 Chapter 1: The Earth System The Scientific Method - Testable hypothesis—working model - Theory – becomes a model - Model – challenged SM ongoing process Earth’s Shape and Surface (topography) - shape and size of Earth- radius=6400 km. Circumference=40,000km -Eratosthenes-Greek who determined Earth’s size 250 BC -bulges at the equator about 44 km - range of Earth surface elevations (land and under sea level) -highest- Mt. Everest 8,848 meters -lowest- Challenger Deep 11,030 meters -avg. change in crust elevation = 20 km The Geologic Record - Principle of Uniformitarianism – James Hutton - “the present is the key to the past” meaning the geological processes we see today worked the same in the past. Geological processes take place over a large range of time (Fast-volcano/meteorite, Slow-mountains/continental drift) Peeling the Onion: Discovery of a Layered Earth - Emil Wiechert - first proposed Earth’s layering. Wondered why the Earth was so dense. Hypothesis: Gravity drop of iron/nickel to the core Therefore: dense core surrounded by a light silicate mantle - Physical Boundaries (Material Strength) Deals with Plate Tectonics - lithosphere-rigid/brittle- crust and uppermost mantle, subducts -asthenosphere- hot/weak/ductile solid- upper mantle -lower mantle- lower mantle- solid but convects like glass overtime -outer core- liquid -inner core- solid - Chemical Boundaries (chemical and density differences) -Crust- 46% Oxygen, 28% Silicon, 8% Al -Mantle- 44% O2, 21% Si, 22.8% Magnesium -Outer Core- 85% Iron, Nickel/Sulfur/O2 5% -Inner Core- 94% Iron, 6% Nickel Earth as a System of Interacting Components - Climate System (Interactions btw cryosphere, atmosphere, hydrosphere, biosphere) -greenhouse effect: sun warms surface, some heat trapped by water vapor/ CO2/ and other gasses controls weather or else Earth would be frozen. - Plate Tectonics System (lithosphere, asthenosphere, deep mantle) - Plates: lithosphere moving on soft asthenosphere - Convection/gravity help to explain how plates move - Geodynamo System- rapid motion of the liquid outer core stirs up electrical flow in solid inner core causing Earth’s magnetic field- Interactions with Inner and Outer Core - Earth: open or closed system? -Open: Exchanges energy and mass with the rest of the cosmos. Energy from the Sun is absorbed by Earth and energizes the weathering, erosion, etc. Weather is controlled by the amount of energy absorbed and energy that radiates back into space. Mass exchange isn’t as prevalent today (meteorites). An Overview of Geologic Time - Oldest known rocks are 4 billion years old - Chemical and biological evolution of life: Hominids (5Ma). Homo Sapiens (.2Ma). Plants(125Ma). - Earth’s geodynamo system produces a magnetic field: 3500 Ma
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- Oxygen becomes a major gas in the atmosphere: 2700 Ma - Life’s “Big Bang” 600 million years ago is marked by the appearance of a great diversity of multicelled plant and animal life in the fossil record. Since then, evolution has been characterized by periodic mass extinctions followed by new radiations of diversity.
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