The Ocean FloorThe Ocean Floor

Chapter 13 Section 2Chapter 13 Section 2

How Scientists Study the How Scientists Study the Ocean FloorOcean Floor

SonarSonar used from the ocean surfaceused from the ocean surface

Satellite: Used in space Satellite: Used in space SeasatSeasat GeosatGeosat

SonarSonar SoSound und NNavigation avigation aand nd RRanginganging

Scientists Scientists send sound waves to the bottom send sound waves to the bottom of the ocean by shipof the ocean by ship..

The The sound waves bounce off the ocean sound waves bounce off the ocean floor and return to the ship.floor and return to the ship.

The The deeper the ocean, the longer it takes deeper the ocean, the longer it takes for the sound waves to returnfor the sound waves to return..

How Scientists Study the How Scientists Study the Ocean FloorOcean Floor

SonarSonar used from the ocean surfaceused from the ocean surface

Satellite: Used in space Satellite: Used in space SeasatSeasat GeosatGeosat

SONAR-FYISONAR-FYI Measuring Water Depth:Measuring Water Depth:

Today's oceanographers use sonar Today's oceanographers use sonar instruments to generate a sound signal instruments to generate a sound signal that is bounced or "echoed" off the sea that is bounced or "echoed" off the sea floor and then recorded on board the floor and then recorded on board the ship.ship.

The speed of sound in water is 1,500 m The speed of sound in water is 1,500 m per second, four times faster than the per second, four times faster than the speed of sound in air.speed of sound in air.

SONAR-FYISONAR-FYI Measuring Water Depth:Measuring Water Depth:

By carefully measuring the round-trip time By carefully measuring the round-trip time of the sound waves and taking into account of the sound waves and taking into account the variables of temperature and salinity, the variables of temperature and salinity, the depth of the water and the distance to the depth of the water and the distance to another object can be measured accurately.another object can be measured accurately.

Sonar is also how bats fly since they are Sonar is also how bats fly since they are blind—hence the idiom “blind as a bat.”blind—hence the idiom “blind as a bat.”

Seasat: launched in 1978 & Seasat: launched in 1978 & focused on the oceanfocused on the ocean

Seasat sends images to Earth that measure Seasat sends images to Earth that measure direction and speed of ocean currents.direction and speed of ocean currents.

space.skyrocket.de/doc_sdat/seasat.

http://rst.gsfc.nasa.gov/Sect14/workshop2+.jpg

Geosat- Geosat- Navy SatelliteNavy Satellite Once a top-secret Military Once a top-secret Military

satellitesatellite

Measures the slightest Measures the slightest changes in the height of changes in the height of the ocean’s surfacethe ocean’s surface

Different underwater Different underwater features affect the height features affect the height of the water above them.of the water above them.

Thus, measuring surface Thus, measuring surface height allows scientists to height allows scientists to map the ocean floor & do map the ocean floor & do it faster than with sonar.it faster than with sonar.

http://rst.gsfc.nasa.gov/Intro/Part2_1b.html

A Map of the Ocean Floor A Map of the Ocean Floor Produced by GeosatProduced by Geosat

http://rst.gsfc.nasa.gov/Intro/Part2_1b.html

How Does Geosat Work?How Does Geosat Work?

Source: http://rst.gsfc.nasa.gov/Intro/Part2_1b.html

The Ocean Floor has two The Ocean Floor has two parts:parts:

Continental Continental Margin:Margin: made of continental made of continental

crustcrust based on depth & based on depth &

changes in slopechanges in slope

Made of:Made of: Continental shelfContinental shelf Continental slopeContinental slope Continental riseContinental rise

Deep-ocean basin: Deep-ocean basin: made of oceanic made of oceanic

crustcrust Form near tectonic Form near tectonic

plate boundariesplate boundaries

Abyssal PlainAbyssal Plain Mid-ocean ridgeMid-ocean ridge Rift valleyRift valley Ocean trenchOcean trench SeamountsSeamounts

Twenty Thousand Leagues Twenty Thousand Leagues Under the SeaUnder the Sea, by Jules Verne , by Jules Verne

18701870 His book revived interest in undersea His book revived interest in undersea

explorationexploration

Inspired engineers to solve the Inspired engineers to solve the problems with submarines at that problems with submarines at that time, which allowed scientists to time, which allowed scientists to reach deeper into the oceanreach deeper into the ocean

Continental MarginContinental Margin Continental shelf AContinental shelf A Continental slope BContinental slope B Continental rise CContinental rise C

   

Deep-ocean basinDeep-ocean basin Abyssal Plain EAbyssal Plain E Mid-ocean ridge FMid-ocean ridge F Rift valley FRift valley F Ocean trench HOcean trench H Seamounts D/GSeamounts D/G

AA B

D E F G

H

C

Continental ShelfContinental Shelf Begins at the Begins at the shorelineshoreline Continues until the ocean floor starts Continues until the ocean floor starts

to slopeto slope Depth Depth can reach about 200 meterscan reach about 200 meters

Continental Slope:Continental Slope: Begins atBegins at edge of edge of continental shelfcontinental shelf Continues Continues down down toto the the flat part of the flat part of the

ocean floorocean floor Ranges Ranges between 200 meters to between 200 meters to

about 4000 metersabout 4000 meters

Continental RiseContinental Rise It is the base of continental slope.It is the base of continental slope. Made of large piles of sedimentMade of large piles of sediment

Now you labelNow you label

1.

2.

3.

Abyssal PlainAbyssal Plain Large, wide, Large, wide, flat area of the ocean floorflat area of the ocean floor Covered in mud & remains of tiny Covered in mud & remains of tiny

marine organismsmarine organisms Average depth 4000 metersAverage depth 4000 meters

Abyssal Plain

Sea Creatures of the Abyssal Sea Creatures of the Abyssal PlainPlain

Mid-Ocean RidgeMid-Ocean Ridge Underwater mountain rangesUnderwater mountain ranges Form where tectonic plates pull apart creating a rift Form where tectonic plates pull apart creating a rift

zonezone Rising magma between the plates creates the ridgeRising magma between the plates creates the ridge

Mid-Ocean RidgeMid-Ocean Ridge

Rift Valley: the zone b/w the Rift Valley: the zone b/w the platesplates

As the mid-ocean ridges build up, a rift As the mid-ocean ridges build up, a rift valley forms b/w them in the rift zone.valley forms b/w them in the rift zone.

Rift valley:Rift valley: can be 15 to 30 miles (24 to 48 kilometers) can be 15 to 30 miles (24 to 48 kilometers)

widewide new oceanic crust is being madenew oceanic crust is being made, which means , which means

lots of seismic activity is happeninglots of seismic activity is happening

Hydrothermal ventsHydrothermal vents were discovered were discovered there.there.

Hydrothermal VentsHydrothermal Vents

www.public.asu.edu/~booksh/apps.htm

www.naturalhistorymag.com/0904/0904_feature.html

Rift Valley Rift Valley

Animals of the hydrothermal Animals of the hydrothermal community:community:

www.biosbcc.net/.../04benthon/dsvents.htm

http://newsimg.bbc.co.uk/media/images/41417000/jpg/_41417766_yeti2_ap_203.jpg

Ocean Trench:Ocean Trench: Huge cracks in the deep-ocean basin.Huge cracks in the deep-ocean basin.

Created by Created by oceanic plate pushing beneath oceanic plate pushing beneath continental plate or another oceanic platecontinental plate or another oceanic plate

Deep-sea trenchesDeep-sea trenches are the are the deepest parts deepest parts of the ocean.of the ocean.

The The deepest one, the deepest one, the Marianas TrenchMarianas Trench in the in the South Pacific Ocean, is South Pacific Ocean, is more than 35,000 feet more than 35,000 feet (10,668 meters), or (10,668 meters), or almost almost 6.6 miles6.6 miles (10.6 (10.6 kilometers) kilometers) deep.deep.

A Navy-owned A Navy-owned submarine, the submarine, the Trieste, still holds the record for diving to the bottom of the deepest part of the Marianas Trench, the Challenger Deep, on January 23,1960.

www.worsleyschool.net/.../marianas/trench.html

Seamounts: individual Seamounts: individual mountains of volcanic materialmountains of volcanic material

Formed when Formed when magma pushes its way magma pushes its way through or between tectonic platesthrough or between tectonic plates

If seamounts build up above sea levelIf seamounts build up above sea level (above the height of the ocean’s surface) (above the height of the ocean’s surface) they can become volcanic islandsthey can become volcanic islands Example: Hawaiian IslandsExample: Hawaiian Islands

Seamounts are usually 25 miles (40 Seamounts are usually 25 miles (40 kilometers) in diameter and can be 10,000 kilometers) in diameter and can be 10,000 to 15,000 feet (3000 to 4500 meters) tall. to 15,000 feet (3000 to 4500 meters) tall.

SeamountsSeamounts

Less than 0.1 percent of the world's Less than 0.1 percent of the world's seamounts have been explored to seamounts have been explored to learn what species live on them, but learn what species live on them, but many of the species that have been many of the species that have been found so far are new to science. found so far are new to science.

Piloted Underwater VesselsPiloted Underwater Vessels Alvin,Alvin, the world's first the world's first

deep-sea submersible; deep-sea submersible; 7m long; seats 37m long; seats 3

Used to discover the Used to discover the hydrothermal vents—hydrothermal vents—found in 1977 off of found in 1977 off of the Galapagos islands, the Galapagos islands, recover a lost recover a lost hydrogen bomb, hydrogen bomb, sunken ships, etc.sunken ships, etc.

Alvin can reach a Alvin can reach a maximum depth of maximum depth of about 4,000 meters about 4,000 meters (people can make it (people can make it about 33 meters about 33 meters without harm).without harm). http://coexploration.org/bbsr/

classroombats/assets/images/Alvin.jpg

Alvin at Alvin at workwork

http://coexploration.org/bbsr/classroombats/assets/images/Alvin.jpg

Shinkai 6500- JapanShinkai 6500- Japan Shinkai 6500,Shinkai 6500, a Japanese research a Japanese research

submarine built in 1989, can work at submarine built in 1989, can work at depths down to 6,400 m.depths down to 6,400 m.

World's deepest-diving manned World's deepest-diving manned research submarine. research submarine.

http://pubs.usgs.gov/gip/dynamic/graphics/shinkai.gif

Deep Flight: an underwater Deep Flight: an underwater airplaneairplane

Moves through water like an airplane Moves through water like an airplane moves through airmoves through air

Future models of Deep Flight will be able Future models of Deep Flight will be able to take pilots 11,000m deep.to take pilots 11,000m deep.

http://www.membrana.ru/images/articles/1048860407-0.jpeg

Robotic Vessels: Jason II and Robotic Vessels: Jason II and MedeaMedea

Piloted vessels expensive & Piloted vessels expensive & dangerousdangerous

So scientists use robotic vessels such So scientists use robotic vessels such as Jason & Medeaas Jason & Medea

Can withstand pressures greater Can withstand pressures greater than those found in the deepest part than those found in the deepest part of the oceanof the ocean

Robotic Vessels: Jason II and Robotic Vessels: Jason II and MedeaMedea

Piloted by a person at the surfacePiloted by a person at the surface

Medea is attached to Jason by a tether (a rope-Medea is attached to Jason by a tether (a rope-like connection) & explores above the sea floor.like connection) & explores above the sea floor.

Dr. Robert Ballard, the "Indiana Jones" of the Dr. Robert Ballard, the "Indiana Jones" of the sea, is not only famous for discovering the sea, is not only famous for discovering the sunken remains of the R.M.S. Titanic. He is also sunken remains of the R.M.S. Titanic. He is also founder of the JASON project, which is a highly founder of the JASON project, which is a highly acclaimed year-long curriculum that educates acclaimed year-long curriculum that educates millions of students through scientific millions of students through scientific discovery. discovery.

Jason: a $2.5 million robotic Jason: a $2.5 million robotic vesselvessel

Jason: www.whoi.edu/.../jason/userman_video.html

Medea: www.onr.navy.mil/.../vessels/submersibles3.htm

QuizQuiz 1. What type of ocean feature creates the 1. What type of ocean feature creates the

Hawaiian Islands? Hawaiian Islands? 2. Where in the ocean is pressure the greatest or 2. Where in the ocean is pressure the greatest or

the most intense?the most intense? 3. What is sonar?3. What is sonar? 4. What is an underwater mountain range?4. What is an underwater mountain range? 5. What is an underwater volcano?5. What is an underwater volcano? 6. What is the large, wide feature of the ocean 6. What is the large, wide feature of the ocean

that is covered by mud and remains of marine that is covered by mud and remains of marine organisms?organisms?

7. What is a rift valley?7. What is a rift valley? 8. What is a huge crack in the ocean floor called? 8. What is a huge crack in the ocean floor called? 9. What is the continental rise? What makes it?9. What is the continental rise? What makes it? 10. What makes up the continental margin?10. What makes up the continental margin? 11. What makes up the deep ocean basin?11. What makes up the deep ocean basin? 12. Where do tectonic plates pull apart or move 12. Where do tectonic plates pull apart or move

away from each other?away from each other? 13. What is the deepest part of the ocean?13. What is the deepest part of the ocean?

AnswerAnswerss 1. What type of ocean feature creates the Hawaiian Islands? 1. What type of ocean feature creates the Hawaiian Islands?

Volcanic seamountsVolcanic seamounts 2. Where in the ocean is pressure the greatest or the most 2. Where in the ocean is pressure the greatest or the most

intense? intense? At the bottom in the ocean trenchesAt the bottom in the ocean trenches 3. What is sonar? 3. What is sonar? Using sound waves to map thingsUsing sound waves to map things 4. What is an underwater mountain range? 4. What is an underwater mountain range? Mid-ocean ridgeMid-ocean ridge 5. What is an underwater volcano? 5. What is an underwater volcano? seamountseamount 6. What is the large, wide feature of the ocean that is covered 6. What is the large, wide feature of the ocean that is covered

by mud and remains of marine organisms? by mud and remains of marine organisms? Abyssal plainAbyssal plain 7. What is a rift valley? 7. What is a rift valley? The area b/w the mountains of a mid-The area b/w the mountains of a mid-

ocean ridgeocean ridge 8. What is a huge crack in the ocean floor called? 8. What is a huge crack in the ocean floor called? Ocean Ocean

trenchtrench 9. What is the continental rise? What makes it? 9. What is the continental rise? What makes it? The base of The base of

the continental slope; sediment washed down the slopethe continental slope; sediment washed down the slope 10. What makes up the continental margin? 10. What makes up the continental margin? Continental shelf, Continental shelf,

continental slope, and continental risecontinental slope, and continental rise 11. What makes up the deep ocean basin? 11. What makes up the deep ocean basin? Abyssal plain, mid-Abyssal plain, mid-

ocean ridges, rift valleys, seamounts, & ocean trenchesocean ridges, rift valleys, seamounts, & ocean trenches 12. Where do tectonic plates pull apart or move away from 12. Where do tectonic plates pull apart or move away from

each other? each other? Mid-ocean ridgesMid-ocean ridges 13. Want is the deepest part of the ocean? 13. Want is the deepest part of the ocean? Ocean trenchesOcean trenches

Name the features shown at Name the features shown at W, X, and Z:W, X, and Z:

Label the areas of the Label the areas of the continental margin:continental margin:

Label the areas of the ocean Label the areas of the ocean floor:floor:

W = continental W = continental shelfshelf

X = continental X = continental slopeslope

Y = continental riseY = continental rise Z = abyssal plainZ = abyssal plain

Summary: The Ocean FloorSummary: The Ocean Floor

The continents lie on the The continents lie on the continental platescontinental plates. The . The edges of these plates are under water, and they edges of these plates are under water, and they form the form the continental shelvescontinental shelves. . These shelves slope outward very gently towards the These shelves slope outward very gently towards the

ocean depths. In some places these shelves go out a ocean depths. In some places these shelves go out a long way, up to 900 miles. long way, up to 900 miles.

In other places the shelves are much narrower. These In other places the shelves are much narrower. These shelves are fairly smooth because debris from the land shelves are fairly smooth because debris from the land is falling onto them from the water. is falling onto them from the water.

This debris contains nutrients washed down from the land, This debris contains nutrients washed down from the land, and these nutrients, plus the shallow water, contribute to and these nutrients, plus the shallow water, contribute to the abundance of life forms near the continents.the abundance of life forms near the continents.

Where the continental shelves end, there is a steep Where the continental shelves end, there is a steep drop downwards. This is called the drop downwards. This is called the continental slopecontinental slope. . It plunges down into the dark, cold waters of the ocean. It plunges down into the dark, cold waters of the ocean.

At the bottom of the continental slope there is a an At the bottom of the continental slope there is a an area that slopes gradually downward to blend into the area that slopes gradually downward to blend into the abyssal plainabyssal plain. This is the bottom of the ocean as we . This is the bottom of the ocean as we think of it.think of it.

Summary: The Ocean FloorSummary: The Ocean Floor The ocean floor seems like a different world. There is no sun The ocean floor seems like a different world. There is no sun

light down here. The water is very cold. The pressure of the light down here. The water is very cold. The pressure of the weight of miles of water above this area would easily crush a weight of miles of water above this area would easily crush a submarine.submarine. Tiny flecks of material from the sunlit world float downward and Tiny flecks of material from the sunlit world float downward and

eventually settle on the bottom. There is almost nothing to eat, eventually settle on the bottom. There is almost nothing to eat, and the animals that live here are few and far between. There and the animals that live here are few and far between. There are many different kinds of animals, but they are small and are many different kinds of animals, but they are small and widely scattered. They are able to survive on very little.widely scattered. They are able to survive on very little.

However, it is not all silence and darkness here. The earth's However, it is not all silence and darkness here. The earth's crust is thinnest in the ocean basins, and volcanic eruptions crust is thinnest in the ocean basins, and volcanic eruptions are part of this environment.  Here and there isolated peaks are part of this environment.  Here and there isolated peaks called sea mounts rise above the flat abyssal plain.called sea mounts rise above the flat abyssal plain. However, the most active part of deep ocean geology occurs in However, the most active part of deep ocean geology occurs in

the deep sea trenches, where the ocean floor is spreading apart. the deep sea trenches, where the ocean floor is spreading apart. Lava comes up through the fissures, building up mountains and Lava comes up through the fissures, building up mountains and deep sea vents, called smokers. The constantly up-welling lava deep sea vents, called smokers. The constantly up-welling lava pushes the sea floor away from the trenches and out towards pushes the sea floor away from the trenches and out towards the continents. When the sea floor reaches the continental the continents. When the sea floor reaches the continental plates, it subducts, or slides underneath them, carrying the cold plates, it subducts, or slides underneath them, carrying the cold rocky floor back into the hot mantle of the earth. rocky floor back into the hot mantle of the earth.