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