-"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
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
Most Abundant Mineral
Classification is by texture and composition
Texture overall appearance
Composition refers to the elements and minerals in the rock.
Igneous rocks Texture
- includes glass, typical crystal size, range in crystal size, and gas