MARINE GEOLOGY & GEOGRAPHY

BATHYMETRY

Bathymetry

BATHYMETRY

• THE UNDERWATER

EQUIVALENT TO TOPOGRAPHY

• THE STUDY OF WATER DEPTH

• A BATHYMETRIC MAP SHOWS

FLOOR RELIEF OR TERRAIN AS

CONTOUR LINES

Bathymetry

BATHYMETRY

• INFORMATION COMES FROM:

• ECHOSOUNDERS (SONAR)

• BOUNCE SOUND WAVES OFF

OF OCEAN FLOOR

• MAP THE DISTANCE FROM SEA

LEVEL TO FLOOR

• CURRENT SONAR READS WIDE

BANDS SIMULTANEOUSLY

(MULTIBEAM))

Bathymetry

BATHYMETRY

• INFORMATION COMES FROM:

• SATELLITES

• MEASURE SLIGHT VARIATIONS

IN SEA LEVEL

• SEA LEVEL IS HIGHER ABOVE

MOUNTAINS AND RIDGES

THAN ABYSSAL PLAINS

Bathymetry

BATHYMETRY

• WHO COLLECTS THE DATA?

• ARMY CORPS OF ENGINEERS

• INLAND WATERWAYS, RIVERS,

LAKES

• NATIONAL OCEANIC AND

ATMOSPHERIC ADMINISTRATION

(NOAA)

• OCEANS, SEAS, GULFS

Bathymetry

OCEAN FLOOR FEATURES

• TWO MAIN DIVISIONS:

• CONTINENTAL MARGIN

• CONTINENTAL SHELF

• CONTINENTAL SLOPE

• CONTINENTAL RISE

• OCEAN BASIN

• PLAINS

• TRENCHES

• RIDGES & RISES

• SEA MOUNTS & GUYOUTS

• CORAL REEFS & ATOLLS

Ocean Floor Features

CONTINENTAL MARGIN

• CONTINENTAL SHELF

• SUBMERGED PART OF

CONTINENT

• GENTLE SLOPE TO OCEAN

BASIN

Ocean Floor Features

CONTINENTAL MARGIN

• CONTINENTAL SLOPE

• EXTENDS FROM SHELF BREAK

TO RISE

• BOUNDARY BETWEEN

CONTINENTAL AND

OCEANIC CRUST

• STEEP SLOPE

• CONTAINS SUBMARINE

CANYONS

Ocean Floor Features

CONTINENTAL MARGIN

• CONTINENTAL SLOPE

• SUBMARINE CANYONS

• FORM FROM

• RIVER EROSION

• TURBIDITY CURRENTS

Ocean Floor Features

CONTINENTAL MARGIN

• CONTINENTAL RISE

• FOUND AT BASE OF SLOPE

• FORMED FROM SEDIMENT

DEPOSITION

• GENTLE SLOPE FROM SEA

FLOOR TO SLOPE

Ocean Floor Features

CONTINENTAL MARGIN

• ACTIVE:

• CONVERGENT PLATE BOUNDARIES

• TRENCHES

• NARROW MARGIN/ SHELF

• TECTONICALLY ACTIVE

• PASSIVE:

• NO PLATE BOUNDARY

• WIDE MARGIN/ SHELF

• THICK SEDIMENT

• LITTLE TECTONIC ACTIVITY

Ocean Floor Features

OCEAN BASIN

• OCEAN BASIN FLOOR:

• ABOUT 30% EARTH’S

SURFACE

• BEGINS AT THE

CONTINENTAL RISE

• MOSTLY ABYSSAL PLAINS

WITH OTHER FEATURES

Ocean Floor Features

OCEAN BASIN

• ABYSSAL PLAIN

• FLAT DEEP OCEAN FLOOR

• MAY BE MORE THAN 2

MILES DEEP

• THICK SEDIMENT

ACCUMULATION

Ocean Floor Features

OCEAN BASIN

• TRENCHES

• OCCUR AT SUBDUCTION ZONES

• OCEANIC CRUST IS FORCED INTO

MANTLE

• ASSOCIATED WITH

EARTHQUAKES

• DEEPEST= MARIANA’S TRENCH

• 11000+ M

• LONGEST= PERU-CHILE TRENCH

• 5900+ KM

Ocean Floor Features

OCEAN BASIN

• RIDGES & RISES

• UNDERWATER MOUNTAIN RANGES

• FORMED BY SEA-FLOOR

SPREADING

• CONTAIN CENTRAL RIFT VALLEY

• RIDGES

• STEEP SLOPE (SLOW MOVING PLATES)

• RISES

• GENTLE SLOPE (FAST MOVING

PLATES)

Ocean Floor Features

OCEAN BASIN

• SEAMOUNTS & GUYOUTS

• UNDERWATER VOLCANOES

NEAR RIDGES AND OVER HOT

SPOTS

• MAY EMERGE AS ISLANDS

• SEAMOUNTS- STEEP SLOPE

JUTTING UP FROM SEA FLOOR

• GUYOUTS- FLAT TOP DUE TO

EROSION

Ocean Floor Features

OCEAN BASIN

• CORAL REEFS & ATOLLS

• FORM AROUND VOLCANIC ISLANDS AND

SEAMOUNTS

• ONLY FORM IN SHALLOW WATERS

• DORMANT VOLCANOES/ SEAMOUNTS ERODE

AWAY AND BECOME A BARRIER REEF AND

EVENTUALLY AN ATOLL

• BARRIER REEF- ACTIVELY GROWING CORAL REEF

SURROUNDING A RECEEDING ISLAND

• ATOLL- SHALLOW LAGOON SURROUNDED BY

MATURE CORAL REEF

Ocean Floor Features

Ocean Floor Features

OCEANS OF THE WORLD

• REVIEW

• AVERAGE DEPTH 2.3 MILES

• SALINITY= 35 PPT (3.5% SALT)

• MAJORITY IS <39°F (4°C)

• MAJORITY IS DARK

• CONTAINS >97% OF THE

EARTH’S WATER

Oceans of the World

OCEANS OF THE WORLD

• PACIFIC

• LARGEST

• AVG. DEPTH 14,500 FT

• BASIN COVERS 33% OF THE

EARTHS SURFACE

• HOLDS 52% OF THE EARTH’S

WATER

• RING OF FIRE

• HIGHLY TECTONICALLY ACTIVE

REGION

• 90% OF WORLD’S EARTHQUAKES

• MARIANA TRENCHOceans of the World

Oceans of the World

OCEANS OF THE WORLD

• ATLANTIC

• 2ND LARGEST

• AVG DEPTH 12,500 FT

• MANY SHALLOW MARINAL SEAS

• LARGE MARGINS

• MID-ATLANTIC RIDGE

• MOSTLY UNDERWATER MOUNTAIN

RANGE

• SOME PEAKS RISE ABOVE SEA LEVEL

TO FORM ISLANDS

• MANY BARRIER ISLANDS

INCLUDING THE LONGEST S. PADRE

Oceans of the World

OCEANS OF THE WORLD

• INDIAN

• SMALLEST OF THE LARGER OCEANS

• AVG DEPTH 13,000 FT

• ALMOST COMPLETELY IN THE S.

HEMISPHERE

• 3 OF THE WORLDS LARGEST RIVERS

DUMP INTO THE NORTH INDIAN

• CONTRIBUTES TO HIGH LEVELS OF

SEDIMENT AND FRESHWATER IN THE

OCEAN

Oceans of the World

OCEANS OF THE WORLD

• SOUTHERN

• NEWEST OCEAN

• AVG DEPTH 13,100 FT

• ONLY OCEAN THAT COVERS A FULL

360°

• OCEAN IS SEPARATE FROM

BORDERING OCEANS DUE TO

ANTARTIC CIRCUMPOLAR CURRENT

• YOUNGEST OCEAN GEOLOGICALLY

SPEAKING

Oceans of the World

OCEANS OF THE WORLD

• ARCTIC

• SMALLEST OCEAN

• AVG DEPTH 3,500 FT

• UNIQUE BECAUSE IT IS

ALMOST COMPLETELY

SURROUNDED BY LAND

• COVERED IN ICE MOST OF THE

YEAR

• ONLY 2% OF THE WORLD’S

OCEAN WATER

Oceans of the World