the sea floor - mt. sac...volcano rising from hotspot _____ boundary . examples? divergent ....

The oceans cover 71% of the earth’s surface

The Four Large Ocean Basins

The Arctic Ocean Shallow Low Salinity

Diluted by large rivers

About half covered with permanent ice

Low species diversity Hallmark animals include

polar bear and walrus

Walruses were once common around the perimeter of the Arctic, but large-scale hunting has

greatly reduced their numbers

Features of Atlantic Ocean

Georges and Grand Banks Great expanses of

shallow water that supported cod fisheries for centuries

North Sea One of most

thoroughly studied marine waters on earth

The Manatee

The Pacific Ocean

(36,163 ft.)

Feb 1977 the submersible Alvin dived to a depth of 2500m over the Galapagos ridge. That is when hydrothermal vents were discovered.

The Galapagos Ridge

Equator

The deep sea submersible Alvin

Hydrothermal Vents

Water is heated by magma and absorbs metals from earth’s crust

Marine Iguana

The Indian Ocean: Relict Species

Coelacanth Stromatolites

Drive from Perinet to Toamasina. Fly to Maroantsetra. Drive to Relais du Masoala Hotel. Two hour boat Ride to Ecolodge on Masoala Peninsula.

Hotel Ecolodge

The Four Large Ocean Basins

The Ocean Basins Are Interconnected The World Ocean

The Antarctic Circumpolar Current (ACC) Formed about 25 MYA

when Australia and South America separated from Antarctica

Isolated the Antarctic continent from warmer waters to the north and is partially responsible for the formation of Antarctica's permanent ice cover.

The northern boundary is called the Antarctic Convergence or the Polar Front.

The Southern Ocean

The Southern Ocean

Antarctic Convergence Divides warm surface

waters of Atlantic, Pacific, and Indian Oceans from cold polar waters.

Abundant krill Summer feeding area

for baleen whales

Large Scale Distribution of Antarctic Krill

Krill are a keystone species in the Antarctic food web. Krill are crustaceans with several larval stages in their life cycle. Some of the larval stages feed on algae that grow on the lower surface of sea ice. One of the factors that determines the annual abundance of krill is the extent of sea ice in winter. Global warming may have significant impacts on krill abundance.

The Antarctic Convergence

Light E Food E

The Sun

Phytoplankton

Krill – Euphausia superba

Baleen Whales Crabeater Seals Leopard Seals Adelie Penguins Chinstrap Penguins Gentoo Penguins

Photosynthesis

The top predators of the Antarctic Peninsula are seabirds and seals.

The Crabeater Seal is a Krill Specialist

Crabeater seals are krill specialists. Their entire “terrestrial” existence is spent on ice floes, not land. Their populations may be increasing due to an increase in krill abundance associated with the decline of baleen whales.

The Structure Of The Earth Core

Mostly iron High Temperature Solid inner and liquid

outer core Swirling motion of

liquid outer core believed to be what creates earth’s magnetic field

Polarity reversals about every 300,000 years

The Structure Of The Earth

Mantle Solid High temperature –

Near the melting point of rocks

It flows Iron and magnesium

silicates

The Structure of the Earth

Crust Outermost layer Extremely thin Composition varies

Continental Versus Oceanic Crust

Continental Granite Low density Light Thick (20 – 50 km) Can be old (3.8by)

Note: Density = Mass Volume

Oceanic Basalt High density Dark Thin (5 km) Young (<200my)

The Lithosphere

Lithosphere = Outer layer of mantle + Crust

The pates involved in plate tectonic motion are plates of the lithosphere

Plates of the Lithosphere

Principles of Plate Tectonics

The plates of the lithosphere carry the continents like passive passengers Pangaea

• 200 million years ago all the continents were combined into one landmass

Pangaea

The average rate of plate movement today is between 2 and 12 centimeters (1 an 5 inches) per year

East Pacific Rise

Mid-Atlantic Ridge

Plate Tectonics

Subduction Zones and Trenches

Oceanic Plate: Label Continental Plate: Label

Collision Between Two Oceanic Plates

Island arc at trench Volcano rising from hotspot

__________ Boundary

Examples?

Divergent

Divergent Boundaries

__________ Boundary

Trenches and volcanoes are associated with this type of boundary

Convergent

Oceanic – Continental Convergence

Peru – Chili Trench Andes Mountains

Transform Boundaries

The San Andreas Fault occurs at a transform boundary

Evidence For Plate Tectonics

Fit of continents Matching sequences of rocks Fossils Mid-Ocean Ridges

Sediment gets (thicker/thinner?) as you move away from crest of mid-ocean ridge

Rocks get (older/younger?) as you move away form the ridges

Fit, Rocks, and Fossils

Mesosaurus Fossils Link Africa and South America

Geological Provinces of the Ocean

Continental Margins

Continental Shelf

Gently sloping Exposed during times

of low sea level Biologically richest part

of ocean 8% of ocean surface

area Submarine canyons Ends as shelf break

The Continental Shelf Off Of Los Angeles

Continental Slope

Steep Edge of continent Along active margins

the slope descends into submarine canyons

Continental Rise

Sediment deposits on ocean floor

Found on passive margins (not active margins)

The Continental Shelf Off Of Los Angeles

Active Versus Passive Margins

Active • Trenches • Narrow shelves • Rocky shorelines

Passive • Flat coastal plains • Wide shelves • Trailing edge of continent

Mid-Ocean Ridges

Seamounts = Submarine Volcanoes Tablemount = Flat Topped Seamount

Copepod

Cyanobacteria (P/S)

Arrow worm

Plankton

The Sun 1-2% Efficient

10% Efficient

10% Efficient

10% Efficient

10% Efficient Herbivorous zooplankton Diatoms and Dinoflagellates

Copepods

Arrow Worms

Fish

Plankton versus Nekton

Plankton Weak swimmers Ride the ocean

currents

Nekton Strong swimmers Can swim against the

currents

Phytoplankton versus Zooplankton

Photosynthetic (P/S)

Autotrophic

Diatoms and Dinoflagellates

Nonphotosynthetic (non-P/S)

Heterotrophic

Copepods

The Sun 1-2% Efficient

10% Efficient

10% Efficient

10% Efficient

10% Efficient

Small carnivorous fishes

Large Carnivorous Fishes

Herbivorous Zooplankton

Brown Pelican