EARTH SYSTEMS
EARTH’S LAYERS
Magma – slowly circulates in
convection cells
Liquid
Core: nickel and iron
solid
Made up of plates
Semi-molten rock (flexible)
http://www.english-online.at/science/geologic-history-of-the-earth/geologic-eras-of-the-earths-history.htm
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
Organic material in various
stages of decomposition
“topsoil”; zone of organic
material and minerals mixed
together
“subsoil”; zone of nutrients
Least weathered layer;
similar to parent material
E Horizon: “zone of leaching”
in acidic soils (found below O)
• 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