EARTH SYSTEMS

EARTH’S LAYERS

http://www.english-online.at/science/geologic-history-of-the-earth/geologic-eras-of-the-earths-history.htm

Core: nickel and iron

solid

Liquid

Magma – slowly circulates in convection cells

Semi-molten rock (flexible)

Made up of plates

THEORY OF PLATE TECTONICS

• Alfred Wegener – “Pangaea”

• Plate Tectonics a. earth’s lithosphere is divided into plates, most

of which are in constant motion b. continental and oceanic plates - movement driven by convection cells

• Plate Boundaries a. Divergent - beneath the oceans - seafloor spreading (brings up important

elements)

b. Convergent - plates collide - subduction (responsible for the Andes in SA) - mountain formation (Himalayas in Asia)

c. Transform Fault - plates slide past each other - “San Andreas Fault”

• Consequences of Plate Movement a. Earthquakes - occurs when rocks of the lithosphere rupture unexpectedly along a fault - fault zones/seismic activity - Richter Scale * measurement of ground movement * increases by a factor of 10

b. volcano - occurs as a plate moves over a hot spot and heat from the mantle melts the crust - as plate moves past the hot spot, leaves behind a trail of extinct volcanic islands (The Hawaiian Islands)

ROCK CYCLE

• “constant formation and destruction of rock”

• Slowest of all Earth’s cycles

• Rock: composed of one or more minerals• Mineral: solid chemical substance with uniform composition

• 3 types of rocks a. Igneous b. Sedimentary c. Metamorphic

• Igneous Rocks a. form directly from magma b. basaltic vs. granitic c. intrusive vs. extrusive

http://geology.com/rocks/igneous-rocks.shtml

http://earth.usc.edu/~slund/systems/topic7.html

• Sedimentary Rocks a. form from sediments being compressed by

other overlying sediments b. typically uniform in composition c. sink for phosphorus d. fossil record

http://saturniancosmology.org/files/geology/sect2_1a.html

• Metamorphic Rocks a. formed when rocks are exposed to extreme temperature and pressures ex) collision of tectonic plates b. structurally strong rocks

WEATHERING AND EROSION

• Weathering a. occurs when rock is exposed to air, water, chemical compounds, animals, etc. b. 2 types - physical * mechanical breakdown of rocks * water, wind, burrowing animals

- chemical

* breakdown by chemical reactions

* acid deposition (“acid rain”)

S emitted into atmosphere, combines with O2

and forms SO2, SO2 reacts with water vapor to

form sulfuric acid

rapid degradation of gravestones, marble,

limestone

• Erosion a. “physical removal of rock from a landscape or ecosystem” b. wind, water, animals c. deposition d. acceleration of erosion - deforestation, overgrazing, road building

SOIL

• Benefits of soil a. plant growth b. primary filter of water c. provides habitat d. filters chemical compounds deposited by air pollution

• Soil Formation a. result of physical and chemical weathering of rocks and gradual accumulation of detritus from the biosphere b. mix of mineral and organic components c. 5 factors - parent material - climate - topography - organisms - time

• Soil Horizons

http://en.wikipedia.org/wiki/Soil_horizon

Organic material in various stages of decomposition

“topsoil”; zone of organic material and minerals mixed together

E Horizon: “zone of leaching” in acidic soils (found below O)

“subsoil”; zone of nutrients

Least weathered layer; similar to parent material

• Soil Properties a. physical - texture * determined by percentage of sand, silt, and

clay * ex) 40% sand, 40% silt, 20% clay - __________ 70% sand, 20% silt, 10% clay - __________

http://www.soilsensor.com/images/soiltriangle_large.jpg

* porosity determines water holding capacity of soil depends on texture

http://www.eoearth.org/view/article/149751/

b. chemical - CEC * cation exchange capacity * nutrient holding capacity * depends on amount of clay particles present - base saturation * soil bases to acids * bases (neutralizers) Ca, K, Mg, Na acids (detrimental) Al, H

c. biological - fungi, bacteria, protozoans - fix nitrogen (essential for plant growth)

http://urbanext.illinois.edu/soil/SoilBiology/images/A-3.jpg

• Soil Degradation a. loss of ability of soil to support plant growth b. due to overuse of land c. one major cause = soil erosion (topsoil

disturbed)

http://www.landfood.ubc.ca/soil200/soil_mgmt/soil_degradation.htm

MINERAL RESOURCES

• Ores – concentrated accumulation of minerals from which economically valuable materials can be extracted - characterized by presence of valuable metals

• Metals – elements with properties that allow them to conduct electricity and heat energy and perform other functions

• Reserve – known quantity of a resource that can be economically recovered

• Mining a. extracting mineral resources b. Types of mining 1. strip mining - removal of “strips” of soil and rock to expose ore - “coal and sand” - return tailing or spoils back to hole

2. open-pit mining - creating of large hole visible from Earth’s surface - “copper mines”

3. mountaintop removal - remove entire top of mountain with explosives - deposits tailings in lower elevation

4. placer mining - use of river water to separate heavier items - example: diamonds, gold

5. subsurface mining - below earth’s surface - “coal, diamonds, and goal”

• Mining Safety - produces tailings which contaminate land and water with acids and metals - subsurface mining * acid mine drainage * accidental burial * inhalation of gases and particles (black lung disease) * explosions

• Mining Regulation - Mining Law of 1872 * regulate mining of silver, copper, gold ore, natural gas and oil on federal lands - Surface Mining Control/Reclamation Act * mandates that land disturbed must be reclaimed after mining process