What is the Earth System?
• The atmosphere (Air) extends
up from the Earth surface for
several hundred kilometers.
• The biosphere (Life) is all
living things, from single-celled
bacteria to plants and animals.
• The geosphere (Land) includes
all minerals, rocks, molten
rock, sediments, and soils
• The hydrosphere (Water)
includes the ocean, rivers,
lakes, streams, groundwater,
water vapor.
• (The cryosphere (Ice) is the
frozen part of the Earth system
and includes snow, glaciers,
and sea ice.)
All systems are connected
“When we try to pick out
anything by itself, we find
it hitched to everything
else in the universe.”
John Muir
“My First Summer in the
Sierra” 1911
Energy Starting Point
• It all starts at the Sun
• Energy from the Sun is
the ultimate source of
almost all energy in the
Earth system!
Geology – study of the earth
I. Earth’s Structure
A. Layers of the Earth–
1. crust – (.5%) – top
layer; thinnest under
oceans (Lithosphere)
2. Mantle (67%) a. Lithosphere (rigid portion - plates)
b. Asthenosphere –
flows due to added
pressure
3. Outer Core – liquid;
(iron & nickel)
4. Inner Core – solid;
(iron & nickel)
Layers of the Earth – temp & pressure
increase as you move down to center
B. Rocks & Minerals – solid portion of
the crust
1. Mineral – solid, inorganic material with the
same chemical make-up, crystalline structure,
& specific properties like color, hardness; ex.
salt, mica, pyrite, quartz, diamond
2. Rock – solid, inorganic material made up of 2
or more minerals
3. Types of Rocks
a. Igneous – crystalline solids which form directly
from the cooling of magma/lava; ex. basalt, pumice,
granite
b. Sedimentary - the accumulation/layering &
compacting of small broken off pieces of preexisting rocks; sandstone, limestone, shale
c. Metamorphic – rocks subjected to different
temperatures & pressures to
“change form”; ex. marble, slate,
quartzite
Igneous
Types of Rocks
Sedimentary
Metamorphic
Marble
Slate
Pumice
Sandstone
4. Rock Cycle
II. Plate Tectonics
A. Theories
1. Continental Drift – 1929 – Alfred Wegener –
proposed continents were originally 1 & then moved
apart
2. Seafloor Spreading – 1960s – Harry Hess seafloor itself moves (and carries the
continents with it; process that occurs where 2
plates meet - new oceanic crust is formed
through volcanic activity and then gradually
moves away from the ridge. )
B. Earth’s Plates
- composed of 7 (8) large or 30 total sections of
the lithosphere (upper mantle + crust) that
move around on the plastic-like asthenosphere:
2 – 10 cm/yr at different directions & speed
C. Plate Movement
1. The heat from the core
of the earth reaches the
mantle. Heat is
transferred to the fluid
layer and the resulting
convection currents
cause the plates to
move.
2. Plate Boundary – place
where 2 plates meet &
move
D. Types of Plate Movement
1. Convergent Boundary - Place where plates crash
or crunch together; can form mts., volcanoes,
earthquakes
2. Divergent Boundary - Place where plates are
coming apart; rifts or valleys form here (Great
Rift Valley in Kenya or the rift near the Rio
Grande; can form volcanoes or earthquakes
3. Transform Boundaries – Place where plates
slide past each other; cause lots of earthquakes
E. Results of Plate Movement Volcanoes & Earthquakes
Tectonic Plates, Volcanoes & Earthquakes
III. Forces on Earth to cause Landforms
(combination)
A. Destructive Forces – processes that destroy
landforms;
1. 2 types: weathering (slow) and Erosion (fast)
2. Ex. landslides, volcanic eruptions, earthquakes
(faulting), floods
B. Constructive forces: forces that build up an
existing landform or create a new one.
1. caused by: water, gravity, wind and glaciers.
2. Ex: deposition of sediment, landslides,
volcanic eruptions, floods
C. Types of Forces at Work
1. Weathering – breaks rocks into sediments
a. Mechanical weathering: the
breaking of rock into smaller pieces by
forces due to gravity, ice, plant roots,
or other physical forces.
b. Chemical Weathering: the changing of
materials in a rock by chemical
processes.
2. Erosion – destructive movement of
materials away from one place by wind,
water, ice, & gravity
Water erosion
wind erosion
glacial erosion
3. Deposition: the placing of
materials in a new place (constructive
force).
Ex. Sandbars
River Deltas – at mouth of
Mississippi River
Deposition by volcanoes
F. Examples of Forces at Work
1. Landslides – gravity quickly pulls rock & dirt
downhill
2. Floods – great flow of water over (usually dry)
land
3. Earthquakes - A sudden movement of the earth's
crust caused by the release of stress accumulated along
geologic faults or by volcanic activity
4. Volcanic Activity - rupture in the crust, which
allows hot magma, volcanic ash and gases to escape
from the magma chamber below the surface
III. Applied Geology
A. Economic geology – locate & manage earth’s
natural resources – ex. petroleum, coal,
minerals
B. Mining geology – extraction of minerals from
the Earth (petroleum geology – petroleum &
natural gas)
C. Engineering geology –works to design
structures based on the features of the Earth
4. Environmental geology – looking at
environmental issues related to natural habitat
& water issues
5. Natural hazards geology – study of the natural
hazards of earth to enact safe building codes &
warning systems used to prevent loss of
property & life