Seafloor Seafloor FeaturesFeatures

Seafloor FeaturesSeafloor Features

ShorelineShoreline – the coast– the coast

Continental Margin – includes: Continental shelf, continental slope, continental rise, submarine canyons, and turbidity currents.

Continental Shelf - Gently sloping part of the continent that is underwater. Used by nations as a legal boundary.

Continental Slope - Zone of steeply sloped sea floor leading from the cont. shelf to the ocean bottom.

Continental Rise - A mound of sediments that separates the cont. slope from the ocean bottom.

Submarine Canyon - An area on the cont. slope carved out by turbidity currents.

Underwater landslides or avalanches called turbidity currents commonly flow down submarine canyons. The debris settles out to build up a submarine fan at the base of the canyon.

Abyssal Plain – broad, flat, and deepest part of the ocean (2000 – 6000 meters deep).

Continental Shelves, Slopes and Abyssal Plains….

Coral reefs are warm, clear, shallow ocean habitats that are rich in life. The reef's massive structure is formed from coral polyps, tiny animals that live in colonies; when coral polyps die, they leave behind a hard, stony, branching structure made of limestone.

3 types of coral reefs:3 types of coral reefs:1.1. Fringing reefs -Fringing reefs - are reefs that form along a coastline. are reefs that form along a coastline.

They grow on the continental shelf in shallow water.They grow on the continental shelf in shallow water.

The fringing reef pictured here surrounds much of

the Polynesian island of Mooréa.

2. Barrier Reefs - 2. Barrier Reefs - Barrier reefs grow Barrier reefs grow parallel to shorelines, but farther out, parallel to shorelines, but farther out, usually separated from the land by a usually separated from the land by a deep lagoon. deep lagoon.

Great Barrier Island, Australia

Eastern Australian Current

3. 3. Coral AtollsCoral Atolls - - are rings of coral that grow on top of are rings of coral that grow on top of old, sunken volcanoes in the oceanold, sunken volcanoes in the ocean. They begin as fringe . They begin as fringe reefs surrounding a volcanic island; then, as the volcano reefs surrounding a volcanic island; then, as the volcano sinks, the reef continues to grow, and eventually only the sinks, the reef continues to grow, and eventually only the

reef remains.reef remains.

What are Coral Reefs…

Trench -Trench - Narrow channels Narrow channels (deepest (deepest places on Earth) places on Earth) ““pinchedpinched”” by by subduction.subduction.

Rift ValleyRift Valley - Runs along the center of the - Runs along the center of the M.O.R. formed by faulting as magma pushed M.O.R. formed by faulting as magma pushed upward.upward.

Mid-ocean RidgeMid-ocean Ridge - The - The topographic expression of sea topographic expression of sea floor spreading centers and floor spreading centers and divergent plate boundaries. divergent plate boundaries.

Volcano – Volcano – cone like feature formed from the cone like feature formed from the uprising of molten rock.uprising of molten rock.

IslandIsland – a body of land – a body of land surrounded by water. surrounded by water.

 Loihi is a new island forming off the Big Island Of Hawaii about 30 miles South west of Kilauea. It's summit is about 1000 meters below the ocean's surface.

Mountain RangeMountain Range – a row of connected – a row of connected mountains formed from lava solidifying from mountains formed from lava solidifying from the MOR.the MOR.

SeamountSeamount - Underwater mtn.s, usually - Underwater mtn.s, usually volcanic.volcanic.

The biggest mtn. on earth is Mauna Loa The biggest mtn. on earth is Mauna Loa (Hawaii)(Hawaii)

What are Seamounts…

GuyotsGuyots - Flat-topped - Flat-topped seamounts, formed from being seamounts, formed from being above sea level.above sea level.

Hydrothermal VentsHydrothermal Vents• Cracks in the ocean Cracks in the ocean

floor through which floor through which boiling hot, chemical-boiling hot, chemical-filled water flows.filled water flows.

• Chimneys form Chimneys form around these vents, around these vents, and organisms and organisms surround these vents surround these vents using chemosynthesis using chemosynthesis to feed.to feed.

Under a microscope, a deep-sea worm’s tentacles—used for feeding—look like cooked spaghetti. WHOI scientists found this worm, called a terebellid, living at hydrothermal vents on the Galápagos Rift off Ecuador.

Hydrothermal Vents – 5 min

Ocean FloorOcean Floor – the bottom of the – the bottom of the ocean.ocean.

A.A.Submarine CanyonSubmarine Canyon

B.B.Continental SlopeContinental Slope

C.C.SeamountSeamount

D.D.MORMOR

E.E. AtollAtoll

F.F. Continental ShelfContinental Shelf

G.G.GuyotGuyot

H.H.TrenchTrench

I.I. Abyssal PlainAbyssal Plain

J.J. Spreading Center or Spreading Center or RiftRift

K.K. Continental RiseContinental Rise

L.L. ShorelineShoreline