What do you know about oceans? Explain at least two things. What do you know about our oceans? Arctic Ocean Baltic Sea Persian Gulf Bay of Fundy Atlantic Ocean Pacific Ocean Indian Ocean Antarctic Ocean Oceans cover 2/3 of the Earth’s surface. Fig. 16.1, p.400

Northern Hemisphere is approximately 39% land. The Hemispheres of the Earth Northern Hemisphere is approximately 39% land. The Southern Hemisphere is approximately 19% land.

Topography There are mountains under the ocean larger than Mt. Everest 15CO, p.374

Mid-oceanic ridges Trenches Island arcs Hot spots

Highest mountain Mt. Everest 8848 meters Average elevation of continents 840 meters Sea level Average depth of oceans – 3800 meters Floor of central oceans about – 5000 meters Deepest ocean trench Mariana trench – 11,000 meters Millions of square kilometers Percent of Area Fig. 15.3, p.377

How do we map the ocean floor? Sonar and Radar Sonar: measuring the time sound waves take to return to ship Known facts: travel time to bottom and back Speed of sound in sea water The distance is determined by plugging these values into a simple formula

Geosat satellite Launched in 1985 Orbits the Earth in about 14 hours The Earth rotates Satellite map of the Earth’s topography, 1.5 years For every increase of 1000 meters on the seafloor, there is 1 meter increase in height of water.

Geosat image of the ocean floor

Active margin: contains a plate boundary

Variations in temperature: From north to south due to the Sun’s radiation

Changes in the Sun’s angle cause variations in the amount of solar energy reaching Earth’s surface.

Variations in Sun’s rays with latitude

Layers of the Ocean: what determines the ocean’s layers?

Temperature: warmer at equator cooler near the poles Surface temperature variations

Three layers: Mixed, Thermocline, Deep zone

Source of salts? Volcanic activity: outgassing Chemical weathering of rocks (dissolved load)

Precipitation

Density determines the vertical position

Intertidal Zone Area between high tide line and low tide line Organisms adapted to harsh, changing environments Intertidal Zone Continental Shelf

Neritic Zone Area over the continental shelf Area of greatest density and diversity of marine life Neritic Zone Continental Shelf

Oceanic Zone From the continental break out to open ocean Oceanic Zone Shelf

Lifestyles 3 Basic Lifestyles: Plankton – float with currents. Can not swim Nekton – Swim freely Benthos – Crawl on the ocean floor. Can not swim

Plankton: microscopic animals and plants Diatom-phytoplankton bottom of the food chain Use basic nutrients from sea water to produce skeletons and soft tissue phytoplankton produce greater than 50% Zooplankton Copepod-1mm Dinoflagellate- 250 microm.

Nekton (swimmers) 5 Categories: Reptiles Mammals Fish Arthropods Mollusks

Nekton (swimmers) Marine Reptiles: Turtles Snakes Crocodiles Iguanas

Benthos (bottom dwellers) Vagrant: Crabs Sea Stars Sea Cucumbers Sea Urchins Brittle Stars

Coriolis effect: earth’s rotation causes gyres

Gyres or circular patterns in the oceans create currents

Fig. 16.13, p.407

Ocean currents influence climate

Tsunami – Great Wave