Chpt. 4 Ocean Floor test
East coast (US), Europe
Passive margin examples
Instruments needed to study the ocean floor
Video and still camera, robust lighting, 2 manipulator arms (can be fitted with different tools), a multi beam system for mapping seafloor
Different types of fish live in certain types of habitats which correlates with the rest of the ocean
What do rockfish have to do with the physical characteristics of the ocean?
Juan de fuca ridge
What does A represent?
Continental shelf
What does B represent?
Astoria canyon
What does C represent?
Astoria fan
What does D represent?
Nitnat fan
What does E represent?
Continental slope
What does F represent?
Gorda ridge
What does G represent?
Cobb seamounts
What does H represent?
Cascadia basin
What does I represent?
-Schools of fish -Plankton -Underwater mountains
What else can be seen using an sonar/echo sounder?
A large carved object (possibly made by humans)
What evidence/artifact was found on the Astoria Canyon/Heceta Bank Cruise?
-Holds a fixed position -Scans ocean floor -Creates images
What makes the NOAA ship R/V Ron Brown such a good oceanic research vessel?
For every 1000 meters of seafloor rise, the sea surface will rise by __ meter
1 meter
Ring of fire, west coast of South America
Active margin examples
Sea level
-Not constant (in the long term) -There was 18% more land mass during the last ice age (Glaciers melt = rise in sea levels) -Sea level rise will vary based on portions of continent being uplifted by plate tectonics
ROPOS
-Remotely operated platform for ocean science -Can dive 3.1 miles (5,000 m) -Instruments: video and still camera, robust lighting, 2 manipulator arms, multi beam system -Can record video and map seafloor
Multi-beam sonar
-Sends out a swath or band of sound (both down and to the sides of the ship) to ping off the seafloor -Beneficial for mapping depths
Side-scan sonar
-Technique that directs sound waves at an angle to the seafloor, allowing underwater topographic features to be mapped -Beneficial for detailed mapping
Oceanic ridge
A continuous elevated zone on the floor of all the major ocean basins and varying in width from 1000-4000km; the rifts at the crests represent divergent plate boundaries
Trench
A deep, steep-sided canyon in the ocean floor, deepest parts of the ocean, and the lowest points on Earth, can also occur at plate boundaries (convergent oceanic and continental)
Submarine canyon
A feature of some continental margins often formed by turbidity currents/underwater landslides
Guyot
A seamount with a flattened top due to wave erosion, was once above sea surface
Abyssal plain
A smooth, nearly flat region of the deep ocean floor
Seamount
A steep-sided volcanic mountain rising from the deep-ocean floor, usually does not grow above the ocean surface
Continental rise
Accumulated sediment found at the base of a continental slope
Sonar/Echo sounders
An instrument used to determine the depth of water by measuring the time interval between emission of a low frequency sound signal and the return of its echo from the bottom, produces more detailed maps of seafloor than satellite altimetry, can also map the sub-seafloor
Continental margin
Edge of continental crust
V = D/T
Equation for velocity
D = (V x T)/2
Equation used for depth in the ocean
Show disturbances in continuous sediment deposits which indicate earthquakes
How do sediment cores support the idea of large earthquakes?
1500 m/s
How fast does sound travel in water?
Satellite Altimetry
Measures the sea surface height from satellite in orbit using radar pulses, maps seafloor by measuring the sea surface which mirrors features on the sea floor (ridges, seamounts, tranches, etc.)
Deep ocean basin
Oceanic plate
Abyssal hill
One of a series of small rolling hills on the ocean floor that occur next to continental margins and oceanic ridges
Continental shelf
Shallow, submerged edge of continent
Bathymetry
The measurement of ocean depths and the charting of the shape or topography of the ocean floor
Continental slope
The steep transition between the continental shelf and continental rise/deep ocean floor
The coastline went out about 30 miles west from where it is today
Where was the Oregon coastline 20,00 years ago?
Rockfish are overfished so different areas are more or less populated, Astoria canyon is somewhat undisturbed by human interference (fishing)
Why study rockfish populations in Astoria Canyon and Hecata Bank?
Active margins
face edges of converging tectonic plates, high volcanic and earthquake activity
Passive margins
face edges of diverging tectonic plates, very little volcanic or earthquake activity