Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
66 Cards in this Set
- Front
- Back
when did oceanographers realize that there was an immense undersea volcanic mountain chain that ran through all of the oceans?
|
in the 1950s
|
|
When was the first comprehensive and generally accurate bathymetric map produced?
|
1959
|
|
what is teh average ocean depth?
|
3.8 km
|
|
what is the pressure (in atmospheres) at a depth of X meters?
|
X/10 + 1 atmospheres (1 atm of air pressure + 1 atm per every 10 meters)
|
|
What are some of the difficulties faced by oceanographers in studying the ocean?
|
- they can't breate in water
- water absorbs light and other forms of EM radiation such as radio and radar waves - ocean is very deep - presure is high - seawater is corrosive - equipment can be fouled, samples contaminated - seawater is slightly conductive, causing short circuits in electronic equipment - sea surface is dynamic |
|
about how many deep ocean soundings had been made by 1910?
|
6000
|
|
when making a sounding, what is the relationship between the amount of wire let out and the actual ocean depth?
|
actual ocean depth is always much less than the amount of wire let out because of currents in deep waters and on the ocean surface
|
|
why must wires used for depth soundings be made several times stronger?
|
they must pull their own weight and the weight of the instruments attached to them
|
|
how do oceanographers solve the problem of wires wrapping around the ship?
|
a Bow Thruster Propeller is attached perpendicular to the direction of the boat to "unravel" the wire
|
|
who made the first successful echo sounding? when?
|
German scientist Alexander Behm, in 1920 (in the North Sea)
|
|
who invented the echo sounder and why? what year?
|
Reginald Fesser in 1912, in order to locate icebergs (becasue of the whole Titanic thing)
|
|
what is the problem with the PDR (Precision Depth Recorder)?
|
it often overlooks undersea hills and mountains?
|
|
who produced the first sea floor map in 1959?
|
Bruce Heezen and Marie Tharp
|
|
What is the difference between the Multibeam Sonar and Sidescan Sonar?
|
-Multibeam Sonar= US; 16 beams are projected in a fan like fashion and the intensity of the returning beams informs scientists of sea floor relief
-SideScan Sonar- British; 2 wide sound beams are projected at an angle from a "fish" towed under the boat; intensity of returning beam informs scientists of sea floor relief |
|
what does SONAR stand for?
|
SOund NAvigation and Ranging
|
|
what was the SEASAT?
|
the first sattelite devoted entirely to oceanographic studies; 1978
|
|
what was the difference between the GEOSAT and SEASAT?
|
GEOSAT, the successor to SEASAT, used a more accurate Radar Altimeter, to determine the height of the sea surface with a precision of 3 to 6 cm
|
|
how were early sediment samples collected?
|
they adhered to a lump of tallow at the end of a sounding line
|
|
what is Sir John Ross famous for?
|
while exploring Baffin Bay in search for the NW Passage in 1820, he used the Deep Sea Clam (an early version of the grab sampler) to collect sea floor sediment
|
|
what is one problem with the grab sampler?
|
it hinges like a clam shell, so the sediment it retrieves is often mixed
|
|
why is the box core better than the grab sampler?
|
it minimizes distrubance because a thin blade slides under the box to prevent sediment from falling out, which also prevents mixing of sediment layers
|
|
how does a corer collect sediment?
|
a tube is forced vertically down by an attached weight with great force; sediment goes inside the tube and is held inside by a core catcher
|
|
what's the difference between a gravity corer and a piston corer?
|
gravity corer- weight lowers it into sediment and falls freely; sediment is driven into the core as it hits the ground with great force
- pisto corer- tube is attached to a release mechanism at the end of a cable; it gets more sediment layers and minimized vertical distortion of core's sediment layers |
|
how big are sediment samples taken by corers?
|
10-30 m
|
|
the Deep Sea Drilling Project, in 1968, used this ship to obtain more than 1000 cores from throughout the world ocean
|
Glomar Challenger
|
|
the Glomar Challenger was replaced by this ship in 1990
|
Joides Resolution
|
|
_______ succeeded the DSDP in 1983
|
Ocean Drilling Project (ODP)
|
|
what countries became members of the ODP?
|
US, Germany, UK, France, Japan, Australia, and and one point, the USSR.
|
|
how old is the oldest sediment sample? what ship retrieved it and how deep was the sample?
|
170 million years old; Joides Resolution; 5700 m
|
|
how does seismic profiling "work"?
|
a sound wave or shockwave is reflected and refracted partially at each sediment layer; different sediment layer reflect different echoes; returning echoes are montitored with a string of HYDROPHONES towed behind a research vessel
|
|
what else, besides seismic profiling, is used to study ocean sediment layers?
|
magnetic field and gravity changes
|
|
what are dredges?
|
steel nets that obtain rocks and Mg and P nodules; dredges must be extremely strong
|
|
what is the diameter and length of the rope that tows a dredge?
|
1 cm; 10 km
|
|
what are sampling bottles used for?
|
to collect water
|
|
how thin is the surface microlayer?
|
100 micrometers
|
|
why is the surface microlayer significant?
|
it often contaminates sampling bottles because the layer contains large quantities of various dissolved chemicals
|
|
what's so special about the GoFlo sampling bottle?
|
it's closed when it is released from the boat, but after it reaches a depth of a few meters, the change in pressure causes it to open and collect seawater from a certain depth; this prevents contamination by the surface microlayer
|
|
why are sampling bottles configured so that water continuously flows in and out of it?
|
to prevent crushing by the immense pressure
|
|
what is used to determine the temperature of a sampling bottle at the time the sample was collected?
|
a reversing thermometer
|
|
why must a reversing thermometer be used?
|
because the high pressures causes the column of mercury to rise higher than it normally would
|
|
what do CTD and STD stand for?
|
CTD = conductivity, temperature, depth
STD = salinity, temperature, depth |
|
describe a Rosette Sampler
|
12 sample bottles are put around a CTD sensor package, which measured salinity and temperature continouously as a function of depth
|
|
true or false: temperature, salinity, and depth sensors are more effective and reliable than pH and turbidity sensors
|
true
|
|
what are the 3 types of current measurement devices?
|
1. passive devices (float)
2. current meters (anchored to ground) 3. remote sensing systems (have remote sensing systems....duh) |
|
give examples of passive sampling devices
|
-Drifters: they float on the surface of the water
-Drift Cards- wash up on the shore and people that find them mail them to oceanographers; useful for determining paths of currents -Swallow floats: neutrally buoyant- float in the middle of 2 different seawater layers of differing density |
|
briefly describe current meters
|
they're anchored to the ground;
some have an impeller that faces the current; others have a rotor that faces vertically; others rely on current meter to tilt the meter body - the meter is oriented to align itself with the current direction with the use of one or more vanes or fins |
|
how is direction determined with current meters?
|
with the use of a magnetic needle inside the meter body
|
|
what does the CAT in CAT scan stand for?
|
computerized axial tomography
|
|
breifly describe acoustic current meters
|
-they're expensive
-they send echoes and current speed and direction are calculated by using the Doppler Shift of the sound frequency of the returning echoes |
|
what is an advantage of the acoustic current meter?
|
it measures current speed and direction at all depths above or below the meter
|
|
how are the smallest pelagic organisms (bacteria, phytoplankton) collected?
|
with the use of sampling bottles or plankton nets
|
|
how are medium sized to large sized marine organisms captured?
|
with a large net (often a km long)
|
|
how are very fragile organisms collected?
|
in a bottle or jar
|
|
describe the "slurp gun"
|
it's a syringe like device used to catch fragile or elusive smallfish and other organisms
|
|
what is an advantage of computer tomography?
|
it can measure current speed in large areas hundreds of square kilometers
|
|
what is an advantage of the JASON-MEDEA system?
|
JASON can return samples to MEDEA instead of going all they way up to the research vessel
|
|
what ROV(s) first explored the Titanic wreck?
|
ARGO and Jason, Jr.
|
|
how long can the JASON-MEDEA system work continuously?
|
about one week
|
|
with what precision can the JASON-MEDEA system reolocate a particular area on the sea floor?
|
a few meters
|
|
how long would it take for a sattelite to survey the entire world ocean?
|
a few days
|
|
what is a disadvantage of using sattelites to study the oceans?
|
since water is a good absorber of EM radiation, sattelites can only study the upper portion of the oceans
|
|
how deep can scuba divers descend (safely)?
|
90 m
|
|
in order to avoid the bends, how long must scientists spend in a decompression chamber after spending several days in an underwater habitat?
|
several days
|
|
what is nitrogen narcosis?
|
a life threatening condition when high pressure air causes high concentrations of nitrogen to build up in the bloodstream, which then produce symptoms similar to those of alcohol intoxication; if the excess nitrogen cannot escape the blood, and forms damaging gas bubbles in the body
|
|
describe the bends
|
a life threatening medical problem caused by a diver breathing high pressure air at a depth for too long and returning to the surface too quickly
|
|
when was the mariana trench visited? by what bathyscape?
|
in 1960; by the Trieste
|