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Oceanography Midterm 1


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What is Oceanography?
An interdisciplinary study of the relationship between geological, biological, chemical, physical, and management processes in the sea.
Inner Planets
Mars, Mercury, Earth, Venus. Also called Telluric Planets. Consist of heavy material and have high boiling and melting temperatures.

Earth is unique because it has an ozone layer, water, and life.

Outer Planets
Saturn, Jupiter, Uranus, and Neptune. Also called Cold Giants. Made of lighter elements and have low melting and boiling temperatures.
Big Bang Theory
15 billion years ago a shock wave from an exploding star caused spinning gravitational attraction around a single point smaller than an atom. The gravitational attraction increased more and more matter until, eventually, the sun and planets formed.
Big Bang Evidence (2 Parts)
Theory of Relativity (Albert Einstein)- says universe is either expanding or contracting

Doppler Effect (Edwin Hubble)- discovered that the universe is expanding

Primordial Soup Theory
Hydrogen, ammonia, methane, and water combined with a catalyst in the ocean to form amino acids which would have been able to combine to create organic material which eventually gave rise to life. Catalysts: electrical discharge, ultraviolet light, geothermal and hydrothermal heat from the ocean floor
Why is water ideal for life?
It retains heat
It moderates temperature
Its a solvent and dissolves many chemicals
And it transports nutrients

Definition of Life
Must be able to grow more complex
Obtain and use energy
and Reproduce

First organism
Primordial Pizza Theory
Same as primordial soup theory but states that this reaction took place on land (a solid surface), because the elements were not sufficient enough to come together with out being torn apart in the ocean.
Panspermia Theory
Suggests that life seeds came from outer space on ice comets and planets exchanged life
Which is the most accepted hypothesis for the origin of life?
Primordial Soup
Which theory of the origin of life has the most funding for further study?
Panspermia Theory
Formation of earth's water sources
3.7 billion years ago earth's surface cooled enough for water to exist primarily as a liquid
outgassing: gases released from volcanic vents, remains as water vapor to create clouds and eventually rain
Comets: tiny ice comets collided with earth and melted providing water

Formation of Atmosphere
3.5-4.5 billion years ago- Carbon Dioxide combined with Water and forms glucose and oxygen for primary production- the oxygen rose up and formed the ozone layer.

Stages of Ocean Exploration
Setting Out (till 100a.d.)
Expanding provincial realms (100-1400a.d.)
Age of Discovery (1400s-1700s)
Charting the World (1700-1900s)
Twentieth Century and Beyond

Characteristics of Setting Out
Used oceans primarily for food- vessels propelled by oars
Greeks used the North Star to measure latitude
Ptolemy's map- produced a map of the roman world including latitude and longitude lines
Aristotle- calculated circumference of the earth, father of oceanography

Characteristics of Expanding Provincial Realms
Vikings did not record anything so we are not able to replicate their ship making skills- but colonized Iceland, Greenland, and Newfoundland
Chinese discovered the compass and used multi-massed ships
passed this info on to arabs to store in alexandria library

HMS Challenger
A 4 year expedition- Captain John Murray- identified almost 5000 new species of marine life, found life existed deep in the ocean, mapped the ocean floor by measuring depth, recorded water temperatures, salinity, and currents, and collected sediment samples from the ocean floor
Characteristics of Charting the World
Two important Expeditions:
The Beagle- charles darwin + origin of species- purpose of expedition was to complete a survey of parts of South America
HMS Challenger- inspired by Darwins work- Captain John Murray- father of Modern Oceanography
SCUBA- Jacques Cousteau and Emile Gagnan develop modern SCUBA

Age of Discovery Characteristics
Voyaging for God, Glory, and GOld
Europe discovered Alexandria Library during the crusades- caught up to the rest of the world
Columbus- first european to reach caribbean
Portugal developed south route- sailed around africa to the west indies

Characteristics of Twentieth Century and Beyond
WWI + WWII spurred scientific voyaging
Radar- Seaset: radar altimetry, measures sea surface height, waves, currents, winds, and ocean floor topography
Bathyscope- manned submersible missiles to help explore depths of the ocean- ALVIN and Trieste

proposed the theory of continental drift and hypothesized that all of the present-day continents were once part of a single supercontinent named Pangaea- wasn't accepted because he couldn't describe how the continents split
Evidence of continental split
Found geological, biological, and meteorological evidence

fit of the continnts
the distribution of fossils
a similar sequence of rocks at numerous location
Ancient climates
apparent wandering of the Earth's polar regions

The one supercontinent before the continental split
Ocean Data Collected in the 1950s
It was a worldwide effort to lay down telecommunication cables

Temperature readings- in areas of high mountain readings the temperature was very high
Sediment analysis with radiometric dating- found newer sediment closer to ridges
Areas with high sysmic activity- found areas with lines of sysmic activity

were then able to map the 7 major plates and the 21 minor plates and form the Plate Tectonics theory

Oceanic Ridges
Compose 22.1% of earths crust
formed by 2 diverging oceanic plates
have spreading centers to make room for new oceanic crust- sometimes extend above sea level
dissected by transform faults and fracture zones + hydrothermal vents are found here

Plate Tectonics
Describes the movement of plates and the forces acting between them- also explains the distribution of many large-scale geologic features that result from movements at plate boundaries

Is the combination of continental drift and sea-floor spreading

Convergent Plates
3 types:
Ocean-ocean: form trenches and maybe island arcs
Ocean-continent: form mountain ranges and trenches (chile)
Continent-continent: forms mountains

Divergent Plates
Lithospheric plates move away from each other- results in ridges- iceland and the red sea
Transform Plates
Plates that slide past each other- earthquakes- San Andreas Fault
Areas of Continental Margin
Active Margins- Pacific Type: immediately after continental slope has trench

Passive Margins- Atlantic Type: after continental slope has rise

Ring of Fire
Line of volcanoes that circles most of the pacific ocean- known as the ring of fire because it is the site of frequent volcanic eruptions
Sea-Floor Spreading
The creation of new oceanic crust at mid-ocean ridges and movement of the crust away from mid-ocean ridges
Greek- means "without bottom"
Very little life
Water has not been mixed since its so deep

Mid-oceanic ridges
Mountain range that surrounds the earth
Most common feature of the ocean
Formation of hydrothermal vents
Form on ridges
Cold water moves down the cracks in the ridge and becomes superheated from the ridge heat source
rises back up through vents carrying dissolved minerals and gases
10-20 degrees warmer than normal ocean floor bottom

Ocean Trench
Arch Shaped depressions that occur where two plates converge
Geologically active- large earthquakes
Coldest water temperatures
deepest place in Earth's crust

Characteristics of Abyssal Plains
flat, deep sediment covered floor of the ocean
exist between ridges and inactive margins of the continent
sediment has mostly a terrestrial or shallow-water origin

Flat-topped seamounts
become flat-topped from wave erosion during inactive period above sea level
coral reef that forms on top of a guyot
large and steep submerged inactive volcanoes- form in groups near spreading centers- very common in the pacific
Arc Islands
Chain of volcanic islands that parallel trenches

Aleutian Islands, Lesser Antilles, Mariana Islands

Volcanic Island
Form from a stationary hot spot that shoots up lava and produces an island
Plate continues to move and then hot spot shoots up another island


Eustatic Sea Level
Change that has happened throughout geological time due to plate tectonics and climate change
Local Sea Level
Short term changes on sea level
Oceanic vs. Continental Crust
Oceanic Crust is made of Basalt
Continental Crust is made of Granite

Basalt is DENSER than Granite

Turbidity Currents
mixtures of sediment and sea water that are denser than pure sea water and so flow down the continental slope
can do so at tens of kilometers per hour
can be slow and steady or large catastrophic events triggered by an earthquake

Ex: Congo Canyon, Hudson Canyon

Formation of Earth's Continental Shelf
formed during rifting of continental lithosphere- rifting heats and stretches continental lithosphere, as the spreading center moves away and starts forming oceanic lithosphere, the continental lithosphere cools and sinks below sea level
Area's of Continental Shelf
Continental Shelf, Shelf Break, Continental Slope
Layers of the Earth
1. the crust- thin layer of solid rock, all the features you see around us
2. The Mantle- below the crust is a hot, partly molten layer- made up of thick heavy material
3. The outer core- molten mass of mostly iron with some nickel- extremely hot- material flows because its so hot
4. Inner Core- large ball of iron and nickel- hottest layer, but it is solid because its crushed under he enormous weight of the outer core and the mantle

The two ocean processes that modify secondary coastlines are ________ and _____.
chemical weathering
physical erosion
Primary Coasts
Coasts dominated by land processes
Erosion- formed during low sea level and are now flooded- Chesapeake bay
Depositional- coasts that deposit more material than is removed by marine processes- River Deltas
Volcanic- Formed from lava flows (Hawaii)
Fault- vertical fault movement along a coast can cause land to uplift or subside- horizontal fault movement can cause the opening of a ulf or a linear shoreline

difference between chemically weathered and physically weathered
chemically weathered the rock is dissolved

physically weathered the rock is abraded

Features of a Secondary Coastline
Sea Cliff- precipitous slope caused by collapse of wave cut notches
Wave-Cut Platform- flat platform caused by underwater erosion of bedrock
Sea Cave- cave cut waves at a zone of weakness in the sea cliff
Headland- protrusion in the coastline of more resistant rock
Sea Arch- two caves on opposite sides of a headland join
Sea Stack- A pillar of rock just off a headland formed by the collapse of a sea arch

Longshore Current
moves sediment along the shoreline in a certain direction- caused by the slight angle of the waves on the shoreline

usually doesn't change

Coastal Cells
sector of the coastline where input of land sediment = outflow of sediments onto the continental shelf or submarine canyons
Sand Spit
finger of sand that extends out into the entrance to a bay- forms in the direction of the longshore current and is deposited as the current looses velocity in the bay

curled tip caused by refraction of waves

Bay Mouth Bar
a sand spit that fully closes off the entrance to a bay
a break in the bay mouth bar caused by tidal action
barrier island
exposed sandbars that run parallel to the coast- they are thought to be submerged dunes of a lower sea level

moving islands- migrating both toward the shore and parallel to the longshore current- often flooded during winter storms

the shallow body of seawater between the barrier island and the shore
Longshore bar
where sediment from the longshore trough is deposited just seaward of the trough
Summer vs. Winter profiles
Summer- have gentle beach slope and a sand bar

Winter- steep slpe and no sand bar

Sand on the dunes replenish sand on the beach in the summers- sand gets fixed on the dunes with plants

Biologically Modified Coasts
Coastlines modified by living organisms- like coral reefs and mangrove trees in tropical areas and salt marsh plants in temperate areas
Human Influences on coasts
1950s- massive tourist developments, road + boulevard constructions, littoral drift interruption, global warming
Solutions for coastal erosion
retreat, accommodation, protection
structures to slow beach and cliff erosion
sea walls- concrete or other material
rip-rap- large boulders
tetrapods- interlocking concrete structures
groins and jetties- built to protect beaches or harbor entrances

Problems with sea walls/groins
storms will undermine walls leading to their eventual collapse

they starve long shore current of sand

sea walls may create reflection of wave energy to cause damage elsewhere

Beach Nourishment programs
replace sand from offshore or other sources- requires careful consideration of sad size and composition

very expensive

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