Earth’s Oceans

The water on Earth is divided into oceans 1. Pacific Ocean – biggest The Oceans The water on Earth is divided into oceans 1. Pacific Ocean – biggest 2. Atlantic Ocean 3. Indian Ocean 4. Arctic Ocean – smallest

4.5 billion years ago there were no oceans on earth. Origin of the Oceans 4.5 billion years ago there were no oceans on earth. Volcanoes spewed gases into the air to form the atmosphere

Origin of the Oceans As the Earth began to cool, water vapor began to condense and form rain This rain filled the deeper levels of the Earth’s surface which created our oceans

Composition of the Ocean Ocean water contains many dissolved salts. Running water from rivers carries these salts from land to the ocean

Composition of the Ocean When seawater is evaporated, ions combine to from materials called salts. Sodium and chloride make up most of the ions in seawater.

Salinity is a measure of the amount of salts dissolved in seawater. One kilogram of ocean water contains about 35 g of dissolved salts, or 3.5%

Hotter, drier climates typically have a higher salinity Climate and Salinity Hotter, drier climates typically have a higher salinity Cooler, humid climates have a lower salinity

The three zones are surface zones, thermocline, and deep zone Temperature Zones The temperature of the ocean decreases as the depth increases, the colder the water the more oxygen it can hold. The three zones are surface zones, thermocline, and deep zone

The surface zone is the warm, top layer of the ocean water Temperature Zones The surface zone is the warm, top layer of the ocean water The thermocline is the second layer of the ocean where the temperature drops significantly

Temperature Zones The deep zone is the bottom layer of the ocean where temperature ranges from 1°C to 3°C

The water cycle also takes place in the ocean The three parts are Ocean’s Water Cycle The water cycle also takes place in the ocean The three parts are Evaporation Condensation Precipitation

The oceans absorb and release heat more slowly than land does Holding Heat The oceans ability to absorb and hold heat makes Earth suitable for life The oceans absorb and release heat more slowly than land does

Warm water Circulation Water at the equator is warmer than other regions Currents in the ocean move this warm water around the world This allows coastal lands to have warmer than normal climates

Ocean currents are a mass movement, or flow, of ocean water. An ocean current is like a river within the ocean

Ocean currents are a mass movement, or flow, of ocean water. An ocean current is like a river within the ocean

Currents

Ocean currents are a mass movement, or flow, of ocean water. An ocean current is like a river within the ocean

Surface currents move water horizontally— parallel to Earth’s surface. These currents are powered by wind.

Surface currents move only the upper few hundred meters of seawater.

Origin of Surface Currents The Coriolis effect is the shifting of winds and surface currents caused by Earth’s rotation.

Origin of Surface Currents Because Earth rotates toward the east, winds curve to the right in the northern hemisphere and to the left in the southern hemisphere.

Origin of Surface Currents The Coriolis effect causes currents north of the equator to turn to the right. Currents south of the equator are turned left.

Warm vs. Cold Currents Currents on the west coasts of continents begin near the poles where the water is colder.

Warm vs. Cold Currents East-coast currents originate near the equator where the water is warmer (Gulf Stream Current)

Upwelling Upwelling is a vertical circulation in the ocean that brings deep, cold water to the ocean surface.

Upwelling This water contains high concentrations of nutrients from organisms that died.

Areas of upwelling create important fishing grounds Nutrients promote primary production and plankton growth, which attracts fish. Areas of upwelling create important fishing grounds

Deep Current A deep current is a streamlike movement of ocean water far below the surface caused by differences in density

The density of seawater increases if salinity increases. Density Currents The density of seawater increases if salinity increases. It also increases when temperature decreases.

An important density current begins in Antarctica. Deep Current An important density current begins in Antarctica. As ice forms, seawater freezes, but the salt is left behind in the unfrozen water.

This current then slowly makes its way towards the equator Deep Currents This salt increases the density of the water until it sinks and forms a deep current This current then slowly makes its way towards the equator

In the North Atlantic Ocean, cold, dense water forms. Deep Currents In the North Atlantic Ocean, cold, dense water forms. These waters sink, forming North Atlantic Deep Water.

Intermediate Waters In the Mediterranean, hot temperatures cause water vapor in the ocean to evaporate which increases the salinity of the water

This water is not as dense as the North Atlantic Deep Current Intermediate Waters This water is not as dense as the North Atlantic Deep Current It then forms a middle layer of water called the Mediterranean Intermediate Waters

The Ocean Floor

Studying the Ocean Floor Scientists use sonar to determine the oceans depth The sound moves through the water, bounces off the ocean floor, and returns to the ship

Ocean basins are low areas of Earth that are filled with water The continental shelf is the gradually sloping end of a continent that extends under the ocean to 350 m deep

The Ocean Floor Beyond the shelf, the ocean floor drops more steeply, forming the continental slope. The continental slope extends from the outer edge of the continental shelf down to the ocean floor.

Ocean Basins Beyond the continental slope lie the trenches, valleys, plains, mountains, and ridges of the ocean basin

Ocean Basins In the deep ocean, sediment, derived mostly from land, settles constantly on the ocean floor. These deposits fill in valleys and create flat seafloor areas called abyssal plains.

Some areas of abyssal plains have small hills and seamounts. The Ocean Basins Some areas of abyssal plains have small hills and seamounts. Seamounts are underwater, inactive volcanic peaks

Mid-ocean ridges can be found at the bottom of all ocean basins. Ridges and Trenches Mid-ocean ridges can be found at the bottom of all ocean basins. A mid-ocean ridge is the area in an ocean basin where new ocean floor is formed.

Ridges and Trenches On the ocean floor, subduction zones are marked by deep ocean trenches.

Trenches and Ridges A trench is a long, narrow, steep-sided depression where one plate sinks beneath another. Marianna Trench in Pacific ocean deepest that we have found “Challenger Deep” 11,000 meters.

Pacific Ocean vs. Atlantic Ocean The Pacific Ocean has a much steeper continental slope. It has Submarine Canyons caused by Turbidity Currents. These are fast moving currents that move perpendicular to the shoreline that cut into the continental slope to form a canyon. The Atlantic ocean has more abyssal plains because more rivers empty into into it bringing more sediment

Life Zones Intertidal Zone- found between high and low tide, contains benthos, nekton and plankton. Neritic Zone- low tide to continental shelf , contains, benthos, nekton and plankton. Open sea Zone- largest of the zones, over the ocean floor. a. photosynthetic- surface, contains phytoplankton and zooplankton b. Bathyal zone- small amount of light reaches here, large nekton swim here, most fishing takes place here, also plankton. c. Abyssal zone- to see floor, no light, strange creatures make own light.

There are three groups of organisms that live in the ocean Life in the Ocean There are three groups of organisms that live in the ocean Plankton Nekton Benthos

Plankton Plankton are organisms that float or drift freely near the ocean’s surface Plankton are divided into phytoplankton (plant-like) and zooplankton (animal-like)

Organisms that swim openly in the ocean are called nekton Nekton include mammals (whales, dolphins) and many types of fish

Benthos are organisms that live on or in the ocean floor These include crabs, starfish and coral

The ocean floor is divided into zones based on ecology Oceanic Zones The ocean floor is divided into zones based on ecology The benthic environment is the region near the ocean floor

Intertidal zone is located between high and low tides Benthic Environment Intertidal zone is located between high and low tides Sublittoral zone extends to the edge of the continental shelf

The abyssal zone is found on the abyssal plain Benthic Environment Bathyal zone is located from the continental shelf to the abyssal plane The abyssal zone is found on the abyssal plain

The deepest zone is the hadal zone , found in trenches (abyssal zone) Benthic Environment The deepest zone is the hadal zone , found in trenches (abyssal zone)

Oceanic Zones The pelagic environment is the zone near the ocean’s surface and the middle depths (photosynthetic zone)

The neritic zone covers the continental shelf Pelagic Environment The neritic zone covers the continental shelf Contains the largest concentration of marine life Oceanic zone covers the rest of the ocean floor

Resources from the Ocean The ocean offers a vast supply of resources Food, raw materials, energy and drinkable water are all from the ocean

Fishing has become a multi-billion dollar business over the years Living Resources Fishing has become a multi-billion dollar business over the years Because over fishing has become a problem, fish farms have started to flourish

Seaweed (kelp) is also harvested from the ocean Living Resources Seaweed (kelp) is also harvested from the ocean Seaweed can be used to thicken foods such as jellies and ice cream

Salt can be removed from ocean water by a process called desalination. As seawater evaporates, salt is left behind.

Sea-Floor Minerals Elements such as sulfur and metals like iron, copper, zinc, and silver can be concentrated in holes and cracks along mid-ocean ridges.