The Ocean Floor and Its Sediments

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The Ocean Floor and Its Sediments. Chapter 16. Ocean Floor Features. Divided into 2 main regions Continental margins Ocean basins. Continental Margins. Continental Shelves: Part of the continent that is underwater Extends from the shoreline to the shelf edge. Continental Margins. - PowerPoint PPT Presentation

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The Ocean Floor and Its Sediments

The Ocean Floor and Its SedimentsChapter 16Ocean Floor FeaturesDivided into 2 main regionsContinental marginsOcean basins

Continental MarginsContinental Shelves:Part of the continent that is underwaterExtends from the shoreline to the shelf edge

Continental MarginsContinental slopesBegin at the shelf edgeWhere water depth starts to increase rapidlyCrust changes from continental to oceanic

Continental MarginsActive Continental MarginsShelf is narrow and bordered by an ocean trenchShoreline is rugged with coastal mountainsPlate boundaries

Continental MarginsPassive continental marginsShelf is broadNo bordering trench or coastal mountainsContinental rises are only found at passive marginsNo plate boundaries

Continental MarginsSubmarine canyonsStart on continental shelfContinue all the way to the end of the slopeSometimes formed by rivers emptying into the ocean

Continental MarginsTurbidity Currentsturbid means muddyPowerful currents that run like flash floods down the continental slopesForm when landslides of mud and sand come down the slopesErosion!Build fan-shaped deposits at the mouths of the canyons (abyssal fans)

Continental MarginsContinental RiseGently sloping region between continental slope and ocean basinFormed by deposition of sediment from land brought by turbidity currentsNot found at active continental margins

Ocean BasinsAbyssal PlainsFlattest areas of Earths surfaceMade of sediment from continentsCommon in Atlantic Ocean

Ocean BasinsSeamountsCone-shaped mountain peaks that rise high above the deep ocean floorOften found in clusters or rows near plate boundariesMost abundant in PacificVolcanic originsOcean BasinsGuyots (GHEE-ohs)Flat topped seamountsThought to have been above water, where waves eroded the topsThen crust sank, and guyots are now underwater

Ocean BasinsAtollsRing-shaped coral islandsReef forms around volcanic islandSea floor sinks, and mountain drops lowerNew coral grows on top of old coral, so eventually the mountain is underwater with the ring of coral around where it used to beLagoon in the center

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