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Phys Geology - Chapt. 15, 16, 17, 18, 19, 20, 21, 22, 24


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- Crest
- Trough
- Wave Base = 1/2 WL
Wave Motion
Crest minus trough
Wave Height
Distance from crest to crest
Wave Length
- Energy Derived from wind
- Deep ocean waves there is little to no net foward motion of water
- Only _____ is transmitted in the Deep Ocean
Orbital motion, energy
- _____ (Wave base intersects the shoreface)
- Wave velocity decreases
- Wavelength decreases
- Wave height increases
______ creates a water velocity resutling in erosion, transport, and depostion
Shallow water waves; Swash wash, Transition from Deep to Shallow Water waves
Crashing wave in swash and wash
- System of ______ and Back bays
- Energy is concentrated into the headland due to wave _____ (tendency of wave to bend and become nearly parallel to the coastline)
- Eroision and transport at the _____
- Depostion at the ______
Headlands; refraction; headland; Back bay; Immature Coastlines
______ causes an oblique swash-wash movement along _____
- Net foward motion is called ______ or Current (Current is parallel to the shoreline)
Wave refraction; shoreline; Longshore drift; Mature coastlines
Offshore migrating current perpendicular to the shoreface
Rip Current
(Major source of Sediments for Shorelines and Barrier Islands are _____)
Depostion along shoreface causes bar to migrate seaward
Rip-rap structures built perpendicular to shoreline to deflect longshore current
- Deposition on _____ side
- Eroision on the _____
Jetties; upcurrent; downcurrent
Rip-rap built parellel to the shore line causing depositon or infilling behind _______
______ are the result of the Moon's and Sun's gravitational attraction
Tidal Waves
_______ result from seismic activity or movement of the seafloor
- Warm water
- Shallow water
- Nutreint Rich water
- Oxygenated water
Charles Darwin and Theory of Reefs
Coral Reefs; reef requirements
As the volcano subsides the reef keeps pace by growing from the top up
Conversion of Fringing reefs to Atolls
- Deserts ____ 30 degrees N and 30 degress south Latitude
- Due to high pressure cells in Troposhere
Along; Major Deserts of the world
Rising air over mountains
Wind Shadow
Deflection of unbound surfaces (wind and water) due to the rotation of the Earth. Runs in circular path
Coriolis Effect
Removal of small grained sand and silt leaving a dersert pavement
Polished desert rocks by the abrasion of the wind
Large grained sand and gravel
Creep and roll
Bouncing of large grained sand
Silt and clay causing dust storms
Faces the wind
Windward face
Downwind side
Leeward Slope
Downwind depostion as a series of cross-beds due to sand cascading at the angle of Repose( steepest angle that loose sediment can obtain)
Slip Face
- Tips point downward
- Isolated dunes with limited sand supply
Types of Sand Dunes: Barchan
- Tips point downwind
- "Unlimited" amount of sand supply
Types of Sand Dunes: Transverse
- Blowout from storm winds
- Tips point upwind (on coastlines)
Types of Sand Dunes: Parabolic
Conversion of Semi-Arid Land to desert due to human encroachment (not deforestation)
Supercontinent of the Triassic Period. No explainable physical mechanism for the drifting of the continents
Freshwater aquatic reptile
- Continental rifting in _____ plate boundaries
- Causes the formation of linear lakes in the ____ valley (Mesosaurus)
- Lakes give way to ____ seas
- Finally new oceans
divergent; rift; inland; Significance of Mesosaurus
Part of Divergent plate boundaries. Is represented by the East African rift valley. A major elongate depression bounded by normal faults, where the entire lithoshere is deformed
Continental rifting
Later stages. Is the divergence of the Arabian plate and African plate
- Continental rifting
- Divergent plate boundaries
Red Sea Rift
Initial stages. Seperates Somalian and African plates.
- Continental rifting
- Divergent plate boundaries
East African Rift Valley
Rocks and Mountains are similar ( on both sides of the ocean)in age and compostion in opposite sides of the Atlantic oceans
Rock Evidence
- Early Mesozoic Glaciation when contenants were connected together in Pangea
- Distribution of Fossil Fuel
Paleoclimatic Evidence
Field strain (measured along fault line) equals the Elastic limit of the rock (known for all types) the fault raptures causing an earthquake (relaese of seimeic energy)
- The theory that earthquakes result from energy released by faulting; the sudde
Elastic Rebound Theory
Subsurface source of Earthquake
Surface point directly above the focus. Release of energy from the focus as seimic waves
Fastes wave, propagation of energy is in the direction of the wave. (horizontal)
Primary (P) Wave
Second fastest wave, (horizontal)propagation of energy is lateral to the wave
Secondary (S) Wave
Slowest wave, propagation of energy is vertical as rolling orbital waves. Up and down motion, the destruction wave.
Surface Wave
Distance to the Epicenter
Intensity of an earthquake
Unconsolated material suffers liquefaction (dewatering of the pore space)
Type of Bedrock
Energy release
Magnitude of Earthquake
Descrpitive (Qualitative) Scale from I to XII
Mercalli Scale
Absolute (Quantitative) from 1-10, Measured by the largest amplitude seismic wave from a seismogram recording. The seismogram is the recording. Seimograph is the instrument that records
Richter Scale
Exponential Scale 5 Moderate EQ
Equal to an atomic bomb
Exponential Scale 6
Damage to well built structures (Base Line
Exponential Scale 7
Strong EQ equal to to 10x(#6)
Exponential Scale 8
Severe EQ Equal to 10x10x (#6)
Exponential Scale 9
Heavy Destruction equal to 10x10x10 (#6)
_____ is determined by measuring the time differenes between the ____ converting time to distance, and _______ distances from ____ seperate seimosgraph stations
Epicenter Determination; P&S; triangulation; three
- Probable site for the next large sized EQ
- Frequence of 21 years
- Next quake due 1990
- 6.0 Sept 2004
Earthquake prediciton; Parkfield California
- Earthquakes occur along ______
- Most intense EQ occur along _______ Plate boundaries, i.e. Subduction zones
- Largest EQ have occured in the _______, the Pacific
Plate boundries; Convergent; Ring of Fire; Earthquakes and Plate tectonics
- Velocity of Seimic Waves are dependent on the denisty of the Earth's layers
- S Waves are absorbed in liquids due to lateral shear, therefore, S waves are absorbed at the outer core boundary
Earth's interior
Absence of detection of S waves on the opposite side to the EQ
S Wave Shadow Zone
Where do most earthquakes occur
Convergent plate boundaries
What happens to the S Waves at the outer core boundary?
They are absorbed because the outer core is a liquid
Two plates slide horizontally past each other
- Shearing Force
- Crust is not created or destroyed
Transform Boundaries
Faults will offset the Ridge into a crooked appearing backbone
- Active displacement is _____ the ridge segments
Oceanic Ridge Transform Faults; between
Faults where two plates slide past each usually involving at least one continental plate
- San Andreas fault (Pacific & North Amercian plate)
Continental Transform Faults
Longshore drift is due to
waves striking the shore obliquely
An atoll normally evolves from a fringe or ______
Barrier reef
A cobble that has been polished and abraded by wind action is called a
Wind transports material by?
- Rolling and sliding.
- Suspension.
- Saltation
What causes the migration of sand dunes?
Erosion of sand on the windward side and deposition on the slip face.
The steepest slope of a sand dune faces southwest, if the wind blows steadily from the
What is the point on the Earth's surface directly above the place of origin of an earthquake called?
In P (primary) waves, the particles in a rock body move
Back and forth parallel to the direction in which the wave travels
Which seismic wave type cannot move through a liquid?
S waves
The most intense and Widespread zone of seismic activity occurs
Along convergent plate margins.
Distribution of Coral reefs is
Between 30 degrees N and 30 degress S Latitude
Net forward motion is called..
Longshore drift or Current
- Seperates the African plate from the Arabian plate
- Causes formation of the Dead sea and sea of Galilee
Dead Sea Transform System
- Splits in the sea floor marked by Mafic (basaltic) volcanism and seismic activity
⬢ Forms _____ crust which is ____ than continental crust
⬢ Mild/Quiet Volcanism due to low Viscosity Magma
⬢ Divergent Plate Boundary
Oceanic Ridges; oceanic ; denser
Shows the Rift Valley and Pelagic Sedimentation.
⬢ Pelagic Sediment thickens away from the Ridge
⬢ Oldest oceanic crust is away from the Ridge
Seismic Reflection profile
⬢ Youngest Rock in Iceland is located along the ridge (_____ of the island). The oldest is away.
Observations in Iceland; middle
⬢ French-American Oceanic Project
⬢ Alvin Submersible made a number of stunning observations of the Oceanic Ridge
Direct Observations of the Sea Floor
Long Linear Extension Cracks, parallel to the ridge.
⬢ Due to plates pulling apart
⬢ Site of volcanic and geothermal activity
Results from subsea eruption of lava
Pillow Basalt
Geothermal vents located along ridge system.
⬢ Black due to dissolved mafic mineral content
⬢ Provide heat and nourishment to producers
Black Smokers
⬢ Divergent Plate Boundaries are marked by shallow-focused EQs of mild intensity
Seismicity of Divergent Plate Boundaries
⬢ Gravity Values ____ over the oceanic ridge
⬢ Heat Flow Values _____ over the oceanic ridge
Gravity and Heat Measurements; decrease; increase
The theory that the continents move in relation to one another
Plate movement (Continental Drift)
What is the relationship of the palagic sediment?
Pelagic sediment thickens away from the ridge
Pacific Plate & North American plate
San Andreas Fault
- Plates move toward one another marked by (silicic) volcanism and high intensity seismic activity
- Forms Continental crust which is less dense than oceanic crust
- Explosive Volcanism due to high Viscosity Magma
- “Ring of Fire”
Convergent plate boundaries
- Subduction
- Volcanism
- EQs
- Formation of Island Arcs
- Ex. Japan, Philippines, Indonesia
Oceanic Plate to Oceanic Plate
- Subduction
- Volcanism
- EQs
- Ex., Cascades (Mt. St. Helens - Juan de Fuca & North American plate), Andes Mtns - S. Amercian & Nazca plate
Oceanic Plate to Continental Plate
- No Subduction
- No Volcanism
- Earthquakes
- Ex. Himalayas
Continental Plate to Continental Plate
- Formation of Contiental crust via Continental ______
Series of Protocontinental Slabs (island arcs) that welded onto the N. American Continent
Accreted Terranes
What mechanisms for plate tectonics?
Push, pull due to convection cells
Convection cells within the Asthenosphere create a Ridge push and Slab pull
Driving mechanisms for plate tectonics
- Hotspots are due to relatively small convection cells that fracture the crust and cause Mafic (basaltic) eruptions (No divergence)
Intraplate Hotspots
- Hotspot remains ______
- The oceanic crust _____ across hotspot causing additional Islands to form
Hotspot & Island Chains; stationary; migrates
- Note: Oldest Island
- Note: Active and Extinct Volcanoes
- Note: Direction of Plate movement. (Series of active is moving southeast then plate is moving Northwest)
Hawaiian Island Chain
Example of interplate hotspot system
Yellowstone Cauldera
Fossil Fuels: Oil, Natural gas, and coal
- 85% of our energy needs
(#1 source of energy)
Nonrenewable Resources
- US consumption leveled off in the late 70’s and early 80’s
- US oil production is declining
- Imported oil is increasing
Consumption-Production Cycle
- Solar Energy
- Hydroelectric Power
- Wind energy
- Geothermal Energy
- Tidal Energy
Renewable Resources
- Exponentially Increased in the Last Century
- Somewhat leveling off in last decade
- Current Population approximately 6 Billion
Human Population
Current is parallel to the shoreline
Longshore drift
Coral reefs are located at the Distribution _____ 30 degrees N and 30 degrees South Latitude
Between; Distribution of Coral reefs
1989 World Series earthquake happened where?
San Francisco
Liqiufaction earthquake was in ______
Mexico City
3-D showing _____ nature of Mid-Atlantic ocean
Navaho Sandstone Zion National Park is an example of...
Cross bedding
What kind of tips point upwind on coastlines...
On irregular (immature) shore lines, the energy of a wave is...
Concentrated mostly on the headlands by wave refraction
Longshore drift moves water and sediment...
Along the beach in a zigzag path
In general, we can expect that on an irregular coastline...
Headlands will be eroded and bays will be the sites of deposition
In general, the dominant EROSIONAL landforms in desert regions are developed by...
Running water
Sediment on the ocean floor...
Is thickest toward the subduction zone and thin or absent on the ridges

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