Oceanography Flashcards
What is the Northwest Passage?
A sea corridor through Canada’s archipelago
What is the sea corridor through Canada’s archipelago called?
The Northwest Passage
When was the first voyage attempted to find the NW Passage?
1497
When were John Franklin’s Erebus and the HMS Terror last sighted before being lost to their NW Passage expedition
1845
When did Roald Amundsen successfully sail through the NW Passage?
1905
What were the 4 interdisciplinary sciences mentioned in class in relation to oceanography?
Geology, Chemistry, Physics, and Biology
True or False: Earth’s oceans are evenly divided between northern and southern hemispheres
False
What are the four main ocean basins?
Pacific, Atlantic, Indian, and Arctic
Which world ocean is not considered a true ocean basin (probably)
The Southern Ocean
What makes seas different from oceans?
Seas are partly enclosed by land
Which sea is the exception to the typical definition of a sea?
Sargasso sea
What is the measurement of ocean depths called?
Bathymetry
What is bathymetry?
Measurement of ocean depth and charting of the shape of the ocean floor
Bathymetry is the measurement of ocean depth and the…
…charting of the shape of the ocean floor
What was used to take bathometric measurements historically?
A line
What is involved in taking bathometric measurements today?
Sonar
What is Echo Sounder?
Signals used to take bathometric measurements
What is a continental margin?
Outer margins of continents where continental crush transitions to oceanic crush
Outer margins of continents where continental crust transitions to oceanic crust
Continental margin
Where are passive continental margins located?
Around nearly the entire Atlantic ocean and part of the Indian ocean
What are the two types of continental margins that were discussed in class?
Passive and Active
Which type of continental margins is tectonically inactive?
Passive continental margins
Which type of continental margins is far from plate boundaries?
Passive continental margins
Where are active continental margins mostly located?
Pacific ocean
Which type of continental margins is at plate boundary?
Active continental margins
Which type of continental margins is tectonically active?
Active continental margins
Where do accretionary wedges develop?
Along subduction zones
What develops along the subduction zone of an active continental margin?
An accretionary wedge
Accretionary wedges occur when sediment from the ocean floor is scraped from a subducting oceanic plate and…
…pressed against the edge of the overriding plate
What is subduction erosion?
When sediment is scraped off the bottom of the overriding plate and carried into the mantle by the subducting plate
What is occurring when sediment is scraped off an overriding plate and carried into the mantle by a subducting plate?
Subduction erosion
What is the voyage that is credited with the birth of oceanography?
The HMS Challenger
What are the deepest parts of the ocean?
Deep ocean trenches
Where do most deep ocean trenches occur?
In the Pacific ocean along the Ring of Fire
Trenches occur near sites of plate convergence or divergence?
Convergence
What feature is formed when thick accumulations of sediment bury an otherwise rugged ocean floor?
Abyssal plain
What oceanic features are most likely the most level places on Earth?
Abyssal plains
What is an abyssal plain?
A deep, flat deep ocean feature
Where do oceanic ridges form?
Along well-developed divergent plate boundaries
What forms along well-developed divergent plate boundaries?
Oceanic ridges
What are oceanic ridges?
Underwater mountain ranges
What are underwater mountain ranges called?
Oceanic ridges
What covers the vast majority of the ocean floor?
Sea-floor sediment
What two processes result in the deposition of sea-floor sediment?
Turbidity currents and snow settling
Loose sediment from continental shelf flows down and deposits on ocean floor
Turbidity currents
Organic debris from higher in the water column sinks to the ocean floor
Snow settling
What are the 3 categories of sea-floor sediment?
Terragenous, Hyrdogenous, and Biogenous
What is terragenous sediment derived from?
From land (minerals from weathering)
What is hydrogenous sediment derived from?
From water (minerals that crystallize)
What is biogenous sediment derived from?
From organisms (shells and skeletons)
What is sea-floor sediment a storehouse for?
Climate data
What is salinity?
The total amount of solid material dissolved in water
How is salinity quantified?
Parts per thousand
What type of salt is found in highest quantities in oceans?
Sodium chloride
What two factors determine salinity levels?
Temperature and precipitation
Total amount of solid material dissolved in water
Salinity
Average salinity of oceans
3.5 ppt
Near the equator, there are lower salinities due to…
…extensive rainfall that dilutes surface ocean water
Evaporation being higher than precipitation causes higher or lower salinity?
Higher salinity
At what latitudes does the thermocline exist?
At low to medium latitudes
The layer where temperature changes rapidly with increasing depth
Thermocline
True or False: The thermocline is found at high latitudes
False
What is the word denoting ocean temperature at high latitudes that stays the same and has no thermocline?
Isothermal
What is ocean density?
Mass per unit volume
What other factor determines ocean density?
Temperature
As temperature decreases, density…
…increases
What is the word denoting the rapid increase in ocean density as temperatures decrease at lower latitudes?
Pycnocline
True or False: The pycnocline is absent at higher latitudes
True
What are the four characteristics of ocean water that were discussed?
Salinity, Acidity, Temperature, and Density
The 3 ways marine life zones are divided?
By available light, distance from shore, and depth
Photic zone
Sunlit waters
Aphotic zone
Not sunlit
Intertidal zone
Between high and low tide
Neritic zone
Above continental shelf
Oceanic zone
Beyond continental shelf
Pelagic zone
Above ocean floor
Benthic
Ocean floor
Zone above continental shelf
Neritic zone
Zone beyond continental shelf
Oceanic zone
Zone between high and low tide
Intertidal zone
3 categories of ocean life
Plankton, Nekton, and Benthos
“Bottom dwellers”
Benthos
Marine life too weak to swim against the current
Plankton
Marine life capable of swimming against the current
Nekton
2 subcategories of plankton
Phytoplankton and Zooplankton
The animal component of plankton
Zooplankton
The photosynthetic component of plankton
Phytoplankton
What 2 factors affect primary productivity (photosynthetic productivity)
Amount of solar radiation and nutrient concentrations
The creation of new organic matter by photosynthetic producers
Primary productivity
Primary productivity
The creation of new organic matter by photosynthetic producers
What is the amount of solar radiation like at low latitudes?
Sunlight is constant
How does constant sunlight affect the thermocline at low latitudes?
The thermocline is permanent and prevents the mixing of water layers
What is the amount of solar radiation like at mid latitudes?
Sunlight varies with seasons
When does a temporary thermocline develop at mid latitudes?
In summer
Contaminant levels increase in a marine animal as they age
Bioaccumulation
Bioaccumulation
Contaminant levels in a marine animal increase as they age
Contaminant levels in marine animals increase as energy is transferred up a food chain
Biomagnification
Biomagnification
Contaminant levels in marine animals increase as energy is transferred up a food chain
Prevailing winds provide energy for ocean currents
Surface currents
Huge, circular-moving current systems that dominate the surfaces of oceans
Gyres
What are gyres?
Huge, circular-moving current systems that dominate the surfaces of oceans
What are the five main gyres?
North Pacific, South Pacific, North Atlantic, South Atlantic, and Indian Ocean
The pattern of deflection taken by objects not firmly connected to the ground as they travel long distances around the Earth
The Coriolis Effect
Coastal winds plus the Coriolis Effect cause surface water to move from shore and be replaced by cool, nutrient-rich “upwells”
Coastal up-welling
What is Thermohaline circulation as known as?
Conveyer belt circulation
Extends between lowest tide level and highest elevation on land that is affected by storm waves
Shore
Extends inland from shore
Coastline
Exposed during lowtide
Foreshore
Landward of the hightide shoreline
Backward
Between low tide shoreline and line where waves break at low tide
Nearshore
Seaward of nearshore
Offshore
Accumulation of sediment found along the landward margin of an ocean or a lake
Beach
Energy traveling along interface between ocean and atmosphere
Waves
Separate crests
Troughs
Halfway between crests and troughs
Stillwater level
Distance between wave crest and trough
Wave height
The 3 factors that wave height, length, and period depend on
Wind speed, Wind duration, and Fetch
What is fetch?
Distance wind has traveled across open water
The distance wind has traveled across open water
Fetch
How is the motion waves move in described?
Circular orbital motions
As waves advance toward shore, wave bottom slows and faster waves farther out to sea catch up, decreasing wave length
Wave breaks
At new and full moons, Sun and Moon aligned produce large tidal range
Spring tides
At first and third quarters of Moon, gravitational forces from Sun and Moon act at right angles, offsetting each other and producing smaller tidal range
Neap tides
