4.1 Plate Tectonics

• layers of the Earth: crust (lithosphere), upper mantle (asthenosphere), and mesosphere (lower mantle)

• plates: sit on the asthenosphere or upper mantle; move in all directions; can be continental or oceanic & have multiple boundary types

• plate boundaries: separates layers of the Earth; varies globally

  • convergent plate boundary: plates push toward each other

    • causes volcanoes, releasing magma & earthquakes

  • divergent plate boundary: plates push away from each other

    • volcano ridges or mountains

    • can cause earthquakes

  • transform (strike-slip) plate boundary: plates slide off each other

    • no ridges or volcanoes; shallow frequent earthquakes

• earthquake formation: occur at fault lines or plate boundaries → builds up stress/energy → release of energy causes the earth to shake

• geologic events help to identify plates by creating a pattern of similar area

  • effects of geologic events: earthquakes, volcanic eruption, and tsunamis

• tsunamis: long sea wave

  • can be caused by underwater landslides and earthquakes

  • can cause contaminated water, uplifting trees, and damage to life on land

4.2 Soil Formation and Erosion

• soil: forms from the weathering (mechanical process of breaking down rocks of parent materials (broken down rocks)

  • type of parent material: influences soil chemistry

  • climate: avg temperate, moisture, weathering rate, nutrients, wind redistribution

  • topography: affects erosion (slope of the land)

  • biological factors: microorganism, plant & animal use

  • time: neverending, continuous

• soil profile: combination of soil layers from various types of rock & organism matter

  • surface horizon: basic rock material + human/organic material

  • subsoil: more basic material than organic matter

  • substrata: most parent material

  • bedrock: granite, basalt, limestone, sandstone, etc.

• soil erosion: weathering of soil

  • caused by water, wind, gravity, human factors → water contamination

  • human impact on soil erosion: deforestation (lack of roots on soil) overgrazing (overeating leads to overexposure of top soil layer → vulnerable to wind & rain)

  • pesticides/fertilizers: changes soil chemistry, kills beneficial microorganisms

  • tillage: breaking up soil → preventing it from organic matter accumulation for nutrition

    • sheet erosion: surface layer is removed by water; prevented by maintaining plant cover

    • rill erosion: small channels of water flow in soil → strig cropping or contour plowing)

    • gully erosion: wide cuts in soil from rill erosion → diverting water to other streams and flows

4.3 Soil Composition & Properties

• soil = sand + silt + clay

  • sand: 2 mm to 0.05 mm (allows water to pass through)(takes 1 hour)

  • silt: 0.05 mm to 0.002 mm

  • clay: < 0.002 mm (blocks water from passing through)(takes 100 years)

• soil composition is determined by the percentage of each soil particle → influences soil type (soil triangle)

• soil test: the process of assessing soil content and attributes

  • chemical: nitrogen, phosphorous, pH/acidity

    • fertilizers = increase in nutrients (nitrogen, phosphorus, potassium)

    • tend to have 7.5 pH (basic)

    • rainfall → increases acidity

  • physical: soil composition & water holding capacity

    • amount of sand, silt, and clay → percolation/infiltration

    • percolation: water → ground

    • infiltration: ions/chemicals → ground (same process as percolation)

  • biological: microorganisms

    • contains bacteria, archaea, fungi, earthworms, burrowing animals, etc.

4.4 Earth’s Atmosphere

• atmosphere = 78% nitrogen + 21% oxygen + 1% trace gases (argon, co2, methane, krypton, hydrogen, water, etc.)

  • exosphere: 600-10,00km; continues to rise until outer space

  • thermosphere: 85-600km; rise in temperature due to UV rays

  • mesosphere: 50-85km; drop in temperature as air thins out

  • stratosphere: 20-50km; rise in temperature from ozone formation

  • troposphere: 0-6-20km; air is most dense

4.5 Global Wind Patterns

• air circulates as earth rotates

• convection: changes in density temperature

• coriolis effect: earth’s rotation deflects the wind (hot air in moving but also turning at the same time)

  • leads to routine weather patterns in both hemispheres

4.6 Watersheds

• watershed: highest point/divide in a river

  • tributary: smaller streams meet larger river

  • delta: river meets larger body of water

  • aquifer: groundwater under the river

• source zone: where the water in the river comes from

  • ex. ice cap

• transition zone: after the headwater; clear cold full oxygenated

• floodplain: more sedimentation → less oxygenated filled with more nutrients

• rainwater → runs downhill to river or percolates through the soil to groundwater

4.7 Solar Radiation & Earth’s Seasons

• primary energy source: solar radiation (constant)

• insolation: incoming solar energy

  • = solar radiation/area

  • surface most perpendicular to the sun (equator) = highest insolation

  • smaller angle = larger area of solar radiation spread = smaller insolation value

  • areas near the pole = lower levels of insolation

  • amount of energy is determined by latitude and season

• northern hemisphere seasons:

  • winter solstice: december 21-22; shortest day of the year, polar night

  • autumnal equinox: september 22-23; day = night

  • summer solstice: june 20-22; longest day of the year, midnight sun

  • vernal equinox: march 20-21; day = night

• southern hemisphere seasons:

  • equinox days are the same (opposite of the northern hemisphere)

  • longest day: december 20/21

  • shortest day: june 20/21

4.8 Earth’s Geography & Climate

• land - low specific + no mobility = quicker temperature increase

  • specific heat = amount of energy needed to raise temperature per degree

• water - high specific heat + high mobility = slower temperature increase

  • coastal areas have more stable temperatures as a result of the intersection between water and land (stabilization of temperatures in both parts)

• currents: bodies of water that flow around a piece of land

  • warmer currents bring heat to land, raising temperatures in certain areas and providing humidity

    • ex. brazil, england

  • cooler currents bring coldness to land, dropping temperatures in certain areas and decreasing humidity

    • ex. canada, angola

• rainshadow effect: effect of coastal breezes from the ocean on mountains

• windward side: part of the mountain next to the ocean

  • air rises from the ocean currents → moisture rises → condensation, precipitation, vegetation → cools temperature on the mountain

• leeward side: part of the mountain inland

  • air becomes hot and dry → decreases moisture → arid and dry as it comes down the mountain

• deserts form 30 degrees above and below the equator

4.9 El Niño & La Niña

• enso: el nino southern oscillation

  • series of weather events happens every 3-7 years in southern hemisphere (south america and australia)

• normal wind patterns: wind goes from east to west → causes upwelling of phytoplankton (greater nutrient supply)

• el nino: winds stop traveling or reverse; currents reverse → suppressing upwelling of life → decreased fishing commercialization

  • begins in december to february until june to august

  • countries surrounding australia experience dry weather → droughts, wildfires → habitat destruction

  • countries surrounding south america experience warm & wet conditions → flooding, landslides, etc.

  • pacific jet stream → warmer winters in canada & north america; wetter and colder in southern states; dry winters in midwest usa

  • midwest → drier conditions

• la nina: enhanced neutral conditions

  • stronger currents, wind patterns, etc.

  • warm current moves closer to australian shoreline

  • greater upwelling in south america. (more phytoplankton)

• normal ocean currents: warm current goes from south america to australia → cools down in australia → comes back to south america in oceanic life (upwelling)

  • increased risk of floods and landslides

  • cooler places get cooler and wetter weather, warmer places get warmer

  • polar jet stream → colder winters, drier in midwest and south usa, warmer upper midwest, etc.