Oceans:A Brief IntroDr. Mark A. McGinley

Honors College and Department of Biological Sciences

Texas Tech University

Fun Facts

• 71 % of Earth’s surface covered by oceans– 80 % of Southern Hemisphere– 60 % of Northern Hemisphere

• Ocean average depth- 4,000 meters• Maximum depth 11,000- meters (approx 7

miles) in Marianas Trench• Below 1000 meters the ocean is dark and cold– Largely lifeless

Oceans of the World

Table 1: Surface area of our planet covered by oceans, water and land.

Surface Percent of Earth'sTotal Surface Area

Area (SquareKilometers)

Area (SquareMiles)

Earth's Surface Area Covered by Land

29.2% 148,940,000 57,491,000

Earth's Surface Area Covered by Water

70.8% 361,132,000 139,397,000

Earth's Surface Area Covered by Ocean

65.7% 335,258,000 129,444,000

Pacific Ocean 30.5% 155,557,000 60,045,000

Atlantic Ocean 15.1% 76,762,000 29,630,000

Indian Ocean 13.4% 68,556,000 26,463,000

Southern Ocean 4.0% 20,327,000 7,846,000

Arctic Ocean 2.8% 14,056,000 5,426,000

 

Pacific Ocean

Important Properties of Water

Water is unique in that it is the only natural substance that is found in all three physical states- liquid, solid, and gas—at the temperatures normally found on Earth.

- Hydrologic Cycle

http://ga.water.usgs.gov/edu/waterproperties.html

Important Properties of Water

Water is unusual in that the solid form, ice, is less dense than the liquid form. Thus, ice floats.

Important Properties of Water

Water is called the “universal solvent" because it dissolves more substances than any other liquid.

-wherever water goes, either through the ground or through our bodies, it takes along valuable chemicals, minerals, and nutrients.

- most important biochemical reactions take place among chemicals dissolved in water in cells

Important Properties of Water

Water molecules are highly cohesive-very sticky. Surface Tension.

Important Properties of Water

• Water has a high specific heat index– it absorbs a lot of heat before it begins to get hot.

• This is why water is valuable to industries and in your car's radiator as a coolant.

• The high specific heat index of water also helps regulate the rate at which air changes temperature– why the temperature change between seasons is

gradual rather than sudden, especially near the oceans.

Patterns of Temperature Variation

33o N 34o N

Important Properties of Water

• The relative high density of water allows sound to move through it long distances – ask a whale!

• In sea water at 30°C, sound has a velocity of 1,545 meters per second (about 3,500 miles per hour).

Water

• Often hear references to “fresh water” and “sea water”

• Fresh water has no, or very low concentration of, substances dissolved in it

• Sea water (sometimes referred to as “salt water) has higher concentration of dissolved substances

Salinity

• Salinity– Measures the amount of dissolved inorganic solids

in seawater• Expressed as parts per thousand (ppt) or percent (%)

Sea Water

• Major elements (> 100 ppm)– Chlorine– Sodium– Magnesium– Sulfur– Calcium– Potassium

• Minor elements (< 100 ppm)– Bromine– Carbon– Strontium– Borom– Silicon– Flourine

Structure of the Ocean

• The ocean is not just a giant swimming pool!!

Cross Section of Ocean Basins

Continental Shelf

Continental Shelf

• The average width of continental shelves is about 80 km (50 mi).

• The depth of the shelf also varies, but is generally limited to water shallower than 150 m (490 ft).

• The slope of the shelf is usually quite low, on the order of 0.5°; vertical relief is also minimal, at less than 20 m (66 ft).

Global Continental Shelf

Importance of DepthLight Penetration

Importance of DepthTemperature

Pelagic Zone

Abyssal Pelagic Zone

Hydrothermal Vents