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MARINE GEOLOGY & GEOGRAPHY

MARINE GEOLOGY

Marine Geology

4 LAYERS OF THE EARTH

Layers of the Earth

CRUST

• THICKNESS: VARIES BETWEEN OCEAN & CONTINENTS 5-40 KM

• STATE: SOLID

• ELEMENTS: SILICON, ALUMINUM, CALCIUM, SODIUM, POTASSIUM

• LOCATION OF THE EARTH’S “PLATES”• FLOATS ON THE LAYER BENEATH• LEAST DENSE LAYER

• CONTINENTAL AND OCEANIC CRUSTS

• LITHOSPHERE= CRUSTS + UPPER MOST PART OF MANTLE

Layers of the Earth

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MANTLE

• THICKNESS: 2,750 KM

• STATE: PLASTIC- ABILITY OF A SOLID TO FLOW

• ELEMENTS: SILICON, OXYGEN, MAGNESIUM, IRON, ALUMINUM, CALCIUM

• CONVECTION CURRENTS• DUE TO UNEVEN HEATING IN THIS LAYER• CAUSE THE EARTH’S PLATES TO MOVE

• ASTHENOSPHERE AND MESOSPHERE

Layers of the Earth

OUTER CORE

• THICKNESS: 2,260 KM

• STATE: LIQUID

• ELEMENTS: IRON AND NICKEL

• EXTREMELY HOT

• RESPONSIBLE FOR OUR MAGNETIC FIELD

Layers of the Earth

INNER CORE

• THICKNESS: 1,228 KM

• STATE: SOLID

• TEMPERATURE AND PRESSURE IS SO GREAT, THAT THE METALS ARE SQUEEZED TOGETHER AND CANNOT MOVE.

• ELEMENTS: IRON AND NICKEL

Layers of the Earth

PLATE TECTONICS

• ALFRED WEGENER• KNOWN FOR HIS THEORY ON

CONTINENTAL DRIFT

• 1915- PUBLISHED THE ORIGINS OF CONTINENTS AND OCEANS

• CONTINENTAL DRIFT

• SUPERCONTINENT- PANGEA

Plate Tectonics

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PLATE TECTONICS

• CONTINENTAL DRIFT SUPPORTED BY:• IDENTICAL FOSSILS FOUND ON DIFFERENT CONTINENTS

• CONTINENTS “FIT” TOGETHER LIKE PUZZLE PIECES

• GEOLOGICAL FEATURES MATCH TOGETHER• COAL DEPOSITS IN EUROPE AND N. AMERICA

• MOUNTAIN RANGES IN AFRICA AND S. AMERICA

Plate Tectonics Plate Tectonics

PLATE TECTONICS

• SO WHAT CAUSED THE PLATES TO MOVE APART?

• THE CRUST IS MADE UP OF SEVERAL DIFFERENT PLATES THAT CAN MOVE INDEPENDENTLY OF ONE ANOTHER

• CONVECTION CURRENTS IN THE MANTLE PUSH/PULL THE PLATES

Plate Tectonics

PLATE BOUNDARIES

Plate Tectonics

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DIVERGENT BOUNDARIES

• OCEAN- (SEA-FLOOR SPREADING)• TWO PLATES MOVE AWAY FROM EACH OTHER

• MAGMA MOVES UP TO FILL THE SPACE CREATING NEW ROCK

• FORMS OCEAN RIDGES

• CONTINENTAL-• FORMS RIFT VALLEYS

Plate Tectonics

CONVERGENT BOUNDARIES

• PLATES MOVE TOWARDS EACH OTHER

• AKA: SUBDUCTION ZONES- AREAS OF PLATE DESTRUCTION

• 3 TYPES:• OCEANIC- OCEANIC

• OCEANIC- CONTINENTAL

• CONTINENTAL- CONTINENTAL

Plate Tectonics

CONVERGENT: OCEANIC- OCEANIC

• FORMS:• TRENCHES

• ISLAND ARCS

Plate Tectonics

CONVERGENT: OCEANIC- CONTINENTAL

• FORMS:• TRENCHES

• VOLCANIC ARCS

Plate Tectonics

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CONVERGENT: CONTINENTAL- CONTINENTAL

• FORMS:• MOUNTAINS

Plate Tectonics

TRANSFORM BOUNDARIES

• OCCURS AS TWO PLATES SLIDE PAST EACH OTHER

• NO PLATE DESTRUCTION

• EARTHQUAKES ARE COMMON DUE TO FRICTION

• OFFSETS GEOLOGIC FEATURES

Plate Tectonics

PLATE BOUNDARIES

Plate Tectonics

OTHER CIRCUMSTANCES

• SOME AREAS HAVE PLUMES OF MAGMA CLOSE TO THE SURFACE

• AKA: HOT-SPOTS

• RESPONSIBLE FOR SEVERAL ISLAND CHAINS INCLUDING HAWAII

• MAGMA RISES TO THE SURFACE AT VOLCANOES CREATING NEW ISLANDS

Plate Tectonics

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OTHER CIRCUMSTANCES

• HYDROTHERMAL VENTS• SEA WATER SEEPS THROUGH

CRACKS IN THE CRUST NEAR PLATE BOUNDARIES

• IT GETS HEATED CLOSE TO MAGMA CHAMBERS

• RUSHES BACK TO THE CRUST CARRYING NUTRIENTS

Plate Tectonics

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

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BATHYMETRY

• INFORMATION COMES FROM:

• SATELLITES• MEASURE SLIGHT VARIATIONS

IN SEA LEVEL

• SEA LEVEL IS HIGHER ABOVE MOUNTAINS AND RIDGES THAN ABYSSAL PLAINS

• LIDAR (LASERS)

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

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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

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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

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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

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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

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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