EESC 1000 Test 1

Geocentric model

everything rotates around Earth; inconsistent with reality

Heliocentric model

Galileo observed (with the telescope) that planets moved around the Sun

The photosphere (surface of the Sun) is relatively cool compared to the core

the temperature gradient creates transfer of heat

Fueled by hydrogen fusion

hydrogens fuse/collide together to form helium

Stars

energy producers; very active; characterized by effective (surface) temperature and luminosity (intensity relative to the Sun)

Stars are held together by

 gravity and form galaxies

Our solar system is located at

the edge of the Milky Way spiral/arm

Planets

spherical; (elliptically) orbits a star; surrounded by other incorporated objects

Terrestrial planets

inner planets; small, rocky shells with solid cores; no rings

Gas giants

hydrogen & helium; gaseous or liquid with solid cores; many moons & rings

Ice giants

outer planets (Jovian planets); water, carbon dioxide, and methane (CH4); frozen/solids; moons and rings

Moon

rocky satellite; orbits planet

Asteroid

small rocky/metallic; orbit around the Sun; left over from the beginning of time

Comet

“snowball” of frozen gas, rock, and dust; Kuiper Belt (Neptune) is a source

Meteoroid

small asteroid; floating through space

Meteor

space rock enters Earth’s atmosphere and burn up as a shooting star

Meteorite

hit planet’s surface and create a crater; asteroidal/planetary fragments; never differentiated into a core & mantle

Doppler effect for sound

moving objects get louder as they get closer because they push sound waves together in the direction they’re moving in

Doppler effect for light

as an object approaches, the wavelengths get shorter/higher frequency (blue shift); long wavelengths/lower frequency (red shift) for distant objects → implies object is moving away at great velocities → expansion of the universe began with the Big Bang

Big Bang theory → Nucleosynthesis →

creates hydrogen and helium → form nebulae (particles condense & masses attract) → collisions produce heat & dense regions → first generation stars → fuse hydrogen and helium

Formation of planets

• Supernova explosion ejects elements → elements mix into nebula

• Ice and dust particles condense → become large enough to be attracted through gravity

• Nebula cools & condenses → spinning around larger mass/center → collapse under gravity → protoplanetary disk → dense mass in center → protosun → center temperature increases 

• Heat so high it ejects volatile material (i.e., ice giants)

• More material → planetesimals (with higher gravity + attract more) → protoplanets 

• Earth hit by asteroid → material removed → collides & aggregates in space + rotates around Earth

Crust

silicate rock; solid, low density

Continental crust

granitic; relatively low density; 25-70 km

Oceanic crust

basaltic; relatively high density; 7-10 km

Lithosphere

crust + upper mantle; rigid; breaks when under stress; moves to create tectonic plates

Asthenosphere

plastic; “soft” (doesn’t break, but deforms easily); mostly solid; mushy (like clay); allows for movement of lithosphere

Mantle

silicate rock (peridotite); mostly solid; high density; most of Earth’s volume

Outer core

liquid Fe; lower density than inner core; responsible for magnetic field; Fe is a metal electrical conductor; liquid & solid components moving at different speeds

Magnetic dipole (magnet with North & South pole)

• solar wind bombardes us → protected by magnetic field (magnetosphere) → magnetic field lines compresses on the sunward side & stretches on the opposite side

  • No magnetic field = die of solar radiation

Van Allen belts

rings of high-energy charged particles trapped by magnetic field

Aurora Borealis

charged particles make it past the Van Allen belts toward magnetic poles; magnetosphere doesn’t deflect; collide with air and releases energy (light)

Inner core

solid Fe (high pressure = solid); similar to iron meteorite

Geothermal gradient (geotherm)

• change of temperature with depth

  • Temperature increases dramatically inbetween layers but slowly within layers

  • Crust → melting curve is higher than geotherm → solid

    • Much greater in crust than in mantle

  • Outer core → melting curve is lower than geotherm → liquid

  • Athenosphere → melting curve = geotherm

Primordial heat

generated by kinetic energy of impact and gravitational energy (more material accumulating = more gravitational energy)

Radioactivity

heat-producing radioactive isotopes decaying in Earth’s crust

Pangaea

period of time when all the continents formed one continent

Evidence for the existence of Pangaea

Shape of continents; location of past glaciations; distributions of past climate belts; distribution of fossils; location of geologic units

Location of past glaciations

as one continent, glaciated areas are adjacent to each other = use to form a single, coherent ice sheet; ice forces outwards and glaciers move, scratching the rocks underground and creating glacial striations which indicate what direction the ice was moving (fitting the continents into Pangaea make the striations line up); Pangaea must’ve been located at the polar latitudes to have sustained this massive ice sheet thermally

Distributions of past climate belts

coal deposits indicate tropical climates; salt flats and coral reefs indicate sub-tropical climates; this doesn’t make sense with the current continent; continents connected = predicted environments line up

Distribution of fossils

same species of land-dwelling and coastal species (incapable of crossing oceans) found on different continents

Location of geologic units

same mountain belts (appalachians) now separated by oceans

Bathymetry

study of underwater

Sonar & echosounders

sound waves sent to the sea floor; measure how fast the echo returns

Continental shelf

shallow ocean

Abyssal plain

deep ocean

Continental slope

steep incline between continental shelf & abyssal plain

Mid-ocean ridge (MOR)

fracture zones; mountain range

Ridge-axis

center of MOR; sediments deposited on top of basalt; rocks formed at the ridge-axis get pushed outwards; as you move away, sediments get older & thicker

Sediments thin

ocean younger than continents

Heat from ridge-axis is greater than

abyssal plains

Declination

angle between direction of geographic N (longitude line/spin axis) and magnetic N

Inclination

angle between field line and Earth’s surface

Apparent polar wandering

• perceived movement of Earth’s magnetic poles relative to a continent → if the pole actually moves, all continents would display the same path

  • Continents move relative to one another = different apparent polar-wander path

Reverse polarity

polarity changes (N & S)

Magnetic anomalies

alternation of strips with stronger and weaker magnetic fields

Positive anomalies

magnetic field stronger; seafloor rock polarity = magnetic field polarity → add to stronger magnetic field

Negative anomalies

magnetic field weaker; seafloor rock ≠ magnetic field polarity (reverse polarity) → subtract to weaker magnetic field

Magnetic anomalies are

parallel & symmetric to the ridge-axis

Magnetic stripes

crystallization of basalt during reverse polarity

Crust/mantle boundary (“Moho”)

sharp; mirrors Earth’s topography; peridotite

Lithosphere/asthenosphere boundary

gradational thermal and mechanical transition between lithospheric mantle and asthenospheric mantle

Buoyancy

developed by Archimedes; densityice < densitywater; iceberg sinks until massentire iceberg = massdisplaced water; reflects density & thickness of lithosphere

Isostatic equilibrium

• less dense lithosphere floats on denser asthenosphere; as ice sheets grow, they push down the crust and lithosphere into the asthenosphere and as the ice melts, the isostatic rebound restores the crust to its original position

  • Same thing happens with mountains as sediments are deposited then eroded

Active continental margins

plate boundary; earthquakes occur

Passive continental margins

not a plate boundary; earthquake locations lacking

Divergent plate boundary

• plates moving in opposite directions; lithosophere thickens away from the ridge axis 

  • Oceans enlarge because new material is brought up from asthenosphere at the MOR to create new oceanic crust; creates pillow basalt and/or black smokers 

  • Continents break apart and new MOR form as lithosphere thins & asthenosphere rises → continental rift

Convergent plate boundary

• plates collide; consuming plate = subduction

  • Ocean/continent → denser crust goes down below continental plate = volcanic arc + possible deeper earthquakes

  • Ocean/ocean → denser lithosphere goes down below oceanic crust = volcanic island arc

Transform plate boundary

plates slide past each other; earthquakes common; fracture zones, ridge axis displaced

Hotspots

• melted mantle rises and melts a hole in lithosphere 

  • Hotspot is stationary; as the plates move, hotspot creates new volcanoes in a different location; chain of volcanic islands record the direction and rate of plate movement

Convection currents/cells

heat from below rises; plate motion driven by convention in mantle

Mineral

basic component of rocks; naturally occurring; solid & crystalline material; formed by geologic processes; definable chemical composition (expressed as chemical formula; different minerals because composition varies)

Solid & crystalline material

• atoms bonded in a regular and periodic fashion

  • Physical structure controlled by crystal structure (lattice; spatial and directional alignment) & chemical composition (type of atoms mass, density, interaction with light)

  • Mineral bounded by flat crystal faces

Crystal

• specific periodic arrangement of atoms; have set of faces; faces are always identical

  • Symmetry controls shape and properties

  • Chemical bonds lock atoms into specific geometric angles and repeating patterns

Native/pure elements

Au, Ag, Cu

Halides

bonded to halogen ion (F-, Cl- → CaF2)

Oxides

bonded to oxygen anion (O2 → FeCr2O4)

Sulfides

bonded to sulfide ion (S2- → FeS2)

Sulfates

bonded to sulfate ion (SO42- → CaSO4⋅2H2O)

Carbonates

bonded to carbon ion (CO32- → Cu2(CO3)(OH)2)

Silicates

bonded to silicate ion (SiO44- → (Mg, Fe)3Al2Si3O12)

Silicates are

the most important rock-forming minerals on Earth; classified based on the arrangment of their basic building unit (silicon-oxygen tetrahedron)