Oceans Basins Oceans Basins

Ocean Bathymetry Ocean Bathymetry ►The study of underwater depth and ocean floor.The study of underwater depth and ocean floor.

► In the same way that topographic maps In the same way that topographic maps represent the three-dimensional features of represent the three-dimensional features of overland terrain, overland terrain, bathymetricbathymetric maps illustrate maps illustrate the land that lies underwater. the land that lies underwater.

►Variations in sea-floor relief may be depicted by Variations in sea-floor relief may be depicted by color and contour lines called depth contours or color and contour lines called depth contours or isobaths.isobaths.

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Measuring Bathymetry Measuring Bathymetry Modern Acoustic InstrumentsModern Acoustic Instruments►Side scan Side scan sonarsonar►Towed behind ship. Provides a Towed behind ship. Provides a

detailed bathymetric map.detailed bathymetric map.

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►Side-scan sonarSide-scan sonar is is used to create an used to create an image of large areas image of large areas of the sea floor. of the sea floor.

►This tool is used for This tool is used for mapping the seabed mapping the seabed in conjunction with in conjunction with seafloor samples it is seafloor samples it is able to show able to show differences in differences in material and texture material and texture type of the seabed. type of the seabed.

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Side Scanning SonarSide Scanning Sonar

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Draining the Ocean Draining the Ocean ►https://www.youtube.com/watch?v=HV

JNLSwCGHc

Main Features Main Features

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Ocean AreasOcean AreasThree Major AreasThree Major Areas► Continental Margins:Continental Margins:

Shallow areas close to shore, includes: Shallow areas close to shore, includes: Continental Shelf, Continental Slope and Continental Shelf, Continental Slope and Continental Rise. Continental Rise.

► Deep-ocean basinsDeep-ocean basins Deep areas farther from land; includes Deep areas farther from land; includes

Abyssal plains and oceanic ridgesAbyssal plains and oceanic ridges► Others:Others:

Trenches, Seamounts and Guyots, Atolls Trenches, Seamounts and Guyots, Atolls

Continental AreasContinental Areas►Non-Active Non-Active

Not close to plate boundariesNot close to plate boundaries No major tectonic activityNo major tectonic activity Example: East coast of CanadaExample: East coast of Canada

►ActiveActive Associated with convergent or Associated with convergent or

transform plate boundariestransform plate boundaries Much tectonic activityMuch tectonic activity

Passive and Active Continental Passive and Active Continental MarginsMargins

Instructions:Instructions:►Activity 1:Activity 1:

In groups of 3 or 4, look at the images provided.In groups of 3 or 4, look at the images provided. Discuss the highlighted features for each image.Discuss the highlighted features for each image. Using the characteristics and terms provided, Using the characteristics and terms provided,

match the image with the characteristics and match the image with the characteristics and terms. terms.

►Activity 2:Activity 2: On the sheet provided, label the diagram On the sheet provided, label the diagram Make sure you have definitions for all of the Make sure you have definitions for all of the

terms!terms!

Major Sea Floor Structures:Major Sea Floor Structures:

B. Continental SlopeC. Sea Mount

I. Abyssal Plain

D. Mid Ocean Ridge E. Island F. Continental Shelf

H. Oceanic Trench

G. Guyot

J. Rift

DefinitionsDefinitions►Continental ShelfContinental Shelf – –

Almost flat gradual Almost flat gradual slope seaward at the slope seaward at the edges of the continentedges of the continent

►This is very wide off of This is very wide off of Canada’s maritime Canada’s maritime provinces. (Grand provinces. (Grand Banks and Scotian Banks and Scotian Shelf)Shelf)

► Continental SlopeContinental Slope – – steeper slope steeper slope seaward; contains submarine seaward; contains submarine canyonscanyons

► Continental Rise:Continental Rise: shallower slope shallower slope composed of sediments that have composed of sediments that have fallen from slopefallen from slope

► Abyssal PlainAbyssal Plain – The largest portion of – The largest portion of the earth’s sea bed. Vast, empty and the earth’s sea bed. Vast, empty and usually boring. usually boring.

Seamounts and GuyotsSeamounts and Guyots Both are undersea volcanoes that Both are undersea volcanoes that

originated at a hotspot or along a originated at a hotspot or along a ridgeridge

GuyotsGuyots once reached the surface of once reached the surface of the ocean and have flat, eroded topsthe ocean and have flat, eroded topsSeamountsSeamounts never reached the never reached the surface, so they have pointy topssurface, so they have pointy tops

Example:HawaExample:Hawaii!ii!

Submarine CanyonsSubmarine Canyons►V-shaped indentations in the V-shaped indentations in the

continental shelf, usually ending in a continental shelf, usually ending in a fan shaped wedge of sediments.fan shaped wedge of sediments.

How do submarine canyons form?How do submarine canyons form?►Thought to be fast moving currents Thought to be fast moving currents

and underwater landslides. and underwater landslides.

The Gully!The Gully!► Submarine canyon off Nova Scotia► Marine Protected Area because of the rare corals found

there► The natural gas pipeline goes right by it…problems?

The Gully

Mid-Ocean RidgeMid-Ocean Ridge►A large underwater A large underwater

mountain chain. mountain chain.

►Part of a cast system Part of a cast system extending some extending some 40,000 miles through 40,000 miles through four of the world’s four of the world’s oceansoceans

►Caused by divergent Caused by divergent plate boundariesplate boundaries

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Mid-Ocean RidgeMid-Ocean Ridge

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Mid-Ocean Ridge FeaturesMid-Ocean Ridge FeaturesSeamountSeamount Pillow lavaPillow lava

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Mid-ocean Ridge FeaturesMid-ocean Ridge FeaturesHydrothermal VentsHydrothermal Vents

► Sea floor hot springsSea floor hot springs► Create ecosystems able to survive without Create ecosystems able to survive without

sunlight sunlight ► https://www.youtube.com/watch?v=D69hGvCsWgA

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Hydrothermal VentsHydrothermal Vents

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Ocean Trenches and Volcanic Ocean Trenches and Volcanic ArcsArcs

►Convergent tectonic plates create Convergent tectonic plates create ocean ocean trenchestrenches.. Deepest part of oceansDeepest part of oceans Deepest – Mariana Trench atDeepest – Mariana Trench at

11,022 meters (36,161 feet)11,022 meters (36,161 feet)►Volcanic arc Volcanic arc on non subducted ocean plateon non subducted ocean plate

May produce May produce island arcisland arc, Japan, Japan► Island ArcIsland Arc – A series of islands of volcanic origin, – A series of islands of volcanic origin,

usually found at or near the edge of an ocean usually found at or near the edge of an ocean basin. basin.

AtollsAtolls► A ring shaped island of coral reefs and coral A ring shaped island of coral reefs and coral

debris. These often form over sinking inactive debris. These often form over sinking inactive volcanoes.volcanoes.

Where are atolls?Where are atolls?►Most of the world's atolls are in the Most of the world's atolls are in the

Pacific OceanPacific Ocean and Indian Oceanand Indian Ocean ►The Atlantic Ocean has no large The Atlantic Ocean has no large

groups of atolls other than eight atolls groups of atolls other than eight atolls east of Nicaraguaeast of Nicaragua

Atlantic Topography MapAtlantic Topography Map►Complete the Atlantic Topography Map Complete the Atlantic Topography Map

Activity.Activity.