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the study of the Earth
- -Founder Of Geology
- -"great geological cycle" Many cycles of weathering , erosion, deposition of sediment, transformation of sediment into rock and uplift that starts the weathering again.
- - Earth heat engine with internal heat melting rocks to for magma
- - Theory of Uniformitarianism The process now operating on and in the earth have operated in the past. The earth's internal heat forms mineral veins.
- -"earth has no beginning nor end"
- -Magma flows out as lava(basalt) or intrudes (granite)
Age of The Earth
-4.55 Billion or 4.6Ga yrs old
- - The lithosphere is apart of the crust and upper rigid mantle
- - Is broken into a series of plates.
- -Is made of basalt thin 10km thickness (thin)
- - Made at (MOR) Mid Ocean Ridge
- - Destroyed at subduction zone
- - oldest 200 Million years old
- -density 2.9 g/cm3
- - 4-10km thick; composed of black volcanic rock (basalt)
- - Made of Granite
- - great diversity of Rocks
- -35km thick to 70 km thick
- -4.2 Billion years old
- - Thicker, less dense and older than oceanic crust
Mantle & Core
- -Inner Core Solid
- - Outer Core Liquid Iron (Fe) Nickel (Ni)
- -Mantle 2,700 km thick
- - Crust relatively thin outer layer 4-70km thick, low density 2.7-2.9 g/cm3, active (earthquakes, volcanoes, moving plates ect.) Chemically differs from mantle.
- - Mantle thick layer located below crust and above core. 2,970 km thick 84% of earth's volume. Moho is boundary between Crust and mantle
- - Core Inner/Outer Central Layer of earth 3,500 km thick; Outer Core liquid; Inner Core Solid; Iron and Nickel most common elements. Magnetic Field generated from spinning of outer core liquid.
- - Lithosphere the crust and upper rigid mantle 100 km thick broken into a series of plates
- - asthenosphere 100 to 300 km thick made of hot soft plastic solid that flows
Continental Drift (Alfred Wegener)
- -Alfred Wegener came u with Continental Drift; wrote "The Origin of Continents and Oceans".
- - Super Continent Pangaea 200 Mya
- - broke up into smaller continents
- - Evidence;fit of South america to Africa;Fossil of aquatic freshwater reptile 1 meter long found in South America and Southern Africa; Glossopteris fern found in Africa, Australia, India & South America
- -Evidence of structural similarities Appalachian disappear at Newfoundlandand reappears in British Isles/ Scandinavia
- -Paleoclimates southern land masses fit together at south pole & form glaciers
Harry Herman Hess
- - Captian of WWII Naval ship
- - used sonar survey parts of the Pacific sea floor; Building on the idea of Wegener and Holmes
- - Origin of new seafloor at MOR, movement of sea floor away from ridge to the trench
- - At Trench the old sea floor sinks back into the mantle
- - This is known as sea floor spreading
- - Basalt emerges from a spreading center and cools the direction and polarity of the earth's magnetic field is recorded.
- - during cooling the basalt subsides and moves laterally, so new crust can take it's place.
- - Younger rock will also record the changes in polarity if reversed.
- - Produces alternating high and low intensity magnetic stripes on seafloor
- - High intensity enhanced by normal polarity
- - Low intensity enhanced by reverse polarity
- -magnetic stripes symmetrically distributed from the spreading center
- -Age of oceans increased from center rigde to margin
- -proposed that radioactivity inside earth heats rocks making them plastic and less dense so they would rise upward toward the surface.
- - Continental Drift is caused by flow of the mantle that carries the continents
- - Radioactive decay of uranium to lead 1.6Ga for a rock
J. Tuzo Wilson
- - idea of hotspots as stationary places in mantle where magma is generated.
- - Hotspot/PLUMES form chains of volcanoes because plates move across the hot spot
- - Described transform faults as third type of plate boundary
- - Wilson cycle the rifting of continents, opening of ocean basins, closing of ocean basins and continent collisions.
Georgia's Location as apart of Pangaea
Near the equator; Africa
- - study of rock magnetism
- - Magnetite, Fe3O4
- Curie point 580 degrees C
- Becomes magnetized in direction of earth's magnetic field common trace mineral in basalt
- - Rock magnetism indicates intensity and orientation of the earth's magnetic field.
- - Direction of poles; Dip needle angle of inclination (90 degrees at poles 0 degrees at equator) give latitude; pattern of magnetic stripes on sea floor
- - Polar wonder Paths different tracks for different plates; Plates move relative to magnetic poles
- - north and south magnetic poles;switch north becomes south; south becomes north
- - normal polarity rocks exhibit same magnetism as the present field
- - reverse polarity opposite magnetism
- - combines continental drift and seafloor spreading
- - A theory that proposes earth's outer shell is divided into a series of plates that move relatively to other plates at (1-15cm/year)
- -Plates grow at M?OR and are consumed at subduction zones
Plate Tectonics: Transform Plate Boundaries
- - Transform plate boundaries cuts down through the entire lithosphere
- - Two plates slide past each other going in opposite directions
- - Transform Faults form Transform Plate Boundaries
- - Most Famous San Andreas Fault, Cali.
- - separates North American and Pacific plates.
- San Andreas Fault 1000km long and 15-20km through crust and lithosphere to the top of Asthenosphere (ends at Asthenosphere)
- - Fault is not wide
Plate Tectonics: Divergent Plate Boundaries
- - extensional Plate Boundaries (Divergent) two plates that move away from each other
- -Rocks are cut by faults at Divergent plate
- -Faults formed at extensional boundaries are normal faults
- - Lithosphere is being pulled apart
- -Rocks break generating earthquakes at divergent boundaries
- - Continental rifting occurs when heating causes rocks to expand under tension causing fracturing and stretching.
- - Basaltic melts invade fractures forming new oceans
Mid-Ocean Ridge (MOR)
- - new Ocean crust is formed at MOR
- - divergent plate boundaries occur where underlying warm and plastic asthenosphere is upwelling; which lowers pressure and the mantle rocks form huge volumes of basalt melt.
- -Basalt builds up on sea floor forming MOR
- - 60% of earth's volcanic activity; ridge elevated because warm rocks are less dense and have more volume than normal ocean crust
- - Plate Boundary 70,000km of interconnected ridge; crest 2-3 km above seafloor; width 1,000 to 4,000km
- - Rift Valleys 50 km wide and 2,000 m deep
Convergent Plate Boundaries
- - Two or more plates move towards each other
- -Lithosphere is either consumed of smashed together into mountain range.
- - Subduction Zone seafloor and lithosphere is pulled deep into the mantle
a substance which cannot be broken down into simpler components by chemical means
the smallest particle of an element which can still be recognized chemically as that element
Strong nuclear force
- holds the nucleus of atoms together
- binds protons and neutrons to form nuclei
- operates over short distances and dominant inside nucleus
Weak Nuclear Force
- causes aversions among protons and neutrons within nucleus
- causing radioactivity which includes transformations in protons and neutrons and energy
- Electricity and magnetism
- raises charge on protons and electrons that binds electrons to nuclei to form atoms
- also binds atoms and molecules
- transfers radiation as mass less photons across distances
- Lithophile= crust= silicate minerals
- Siderophile= native elements
- gold and Iron in earths core
- Chalcophile= pyrite and galena
- Naturally occurring
- Generally inorganic
- earth's crust contains 90 elements
Types of Bonding
- Ionic Bond (Halite NaCl) - valance electrons transferred from one atom to another opposites attract
- Covalent Bond(Diamond,C) - 4 atoms share valence electrons strong bond
- Metallic Bond (Gold Au)- mobile valence electrons holds atoms together, electrons move
Most Abundant Elements
- Oxygen 46.1%
- Silicon 28.0%
- Aluminum 8.3%
- Iron 5.6%
- Classification is by texture and composition
- Texture overall appearance
- Composition refers to the elements and minerals in the rock.
- - felsic
Igneous rocks Texture
- - includes glass, typical crystal size, range in crystal size, and gas
- -slow cooling produces smaller crystals