• A gulf is a portion of the ocean that penetrates land. Gulfs vary greatly in size, shape, and depth. They are generally larger and more deeply indented than bays. Like bays, they often make excellent harbors. Many important trading centers are located on gulfs.

    Gulfs may be formed by movements in the Earths crust. The Earths tectonic plates may rift, or break apart, creating a gulf. Or, one plate may fold under another, a process called subduction. Subduction may create a gulf by making downfolds, or troughs, in the rock under the ocean.

    Gulfs are sometimes connected to the ocean by narrow passages of water called straits. Gulfs can also have wide openings and are sometimes indistinguishable from larger bodies of water.

    Major Gulfs

    The Gulf of Mexico, bordered by the United States, Mexico, and the island nation of Cuba, is the worlds largest gulf. It has a coastline of about 5,000 kilometers (3,100 miles). The Gulf of Mexico is connected to the Atlantic Ocean by the Straits of Florida, between Cuba and the U.S. state of Florida. It is connected to the Caribbean Sea by the Yucatn Channel, between Cuba and the Mexican peninsula of Yucatn.

    The Gulf of Mexico is an important economic site for all three countries. The process of upwelling occurs near the Florida coast of the gulf, creating a rich variety of sea life. Upwelling is the process in which cold, nutrient-rich water from the bottom of the gulf is brought to the surface.

    Fish and other organisms thrive in areas of upwelling. Commercial, sport, and recreational fishing thrive in the Gulf of Mexico. Oil deposits sit beneath the western Gulf of Mexico. Both Mexico (in the Bay of Campeche) and the U.S. (mainly around the coasts of Texas and Louisiana) have oil wells in the Gulf of Mexico.

    The Gulf Stream, one of the most powerful ocean currents in the world, originates in the Gulf of Mexico. Gulf ports, including Houston, Texas; New Orleans, Louisiana; Veracruz, Mexico; and Havana, Cuba, continue to be important cities where goods are imported and exported by sea.

    The Gulf of Mexico is also the site of strong storms. Hurricanes and other storms need warm water to develop. The Gulf of Mexico is a very warm body of water, so storms can often increase their strength. Cuba and the U.S. state of Florida are regularly hit by hurricanes on both their Atlantic and Gulf coasts.

    Pollution also threatens life in the Gulf of Mexico. Oil shipping and drilling can spill tons of petroleum into the ecosystem. Two huge rivers, the Mississippi in the U.S. and the Grijalva in Mexico, empty into the gulf. Chemicals used for agriculture and industry have seeped into the water, helping to create one of the largest dead zones in the world. (A dead zone is a region where there is little oxygen or ocean life beneath the surface.)

    River management has redirected the flow of the Mississippi River. Canals, dams, and drainage systems for agriculture and industry have provided power and irrigated land. They have also reduced the wetlands at the rivers mouth and delta. The Gulfs wetlands slow storms as they move toward land. The loss of these wetlands may have contributed to the destruction brought by Hurricane Katrina to the Gulf Coast between central Florida and Texas in 2005.

    The Gulf of Carpentaria, on Australias northeast coast, is an inlet of the Arafura Sea. Because both the sea and the gulf are shallow, the exchange of water between the two is reduced. Sediment collects at the mouth of the gulf, forming underwater barriers. The low shore is bordered in some areas by wetlands and swamps.

    This shallow gulf with a wide mouth creates the conditions for a yearly spectacle called the Morning Glory Cloud. In September and October, sea breezes from the Gulf of Carpentaria and the Arafura Sea meet and create an enormous, fast-moving cloud over the gulf. The Morning Glory Cloud can be 1,000 kilometers (621 miles) long and move at a rate of 60 kilometers per hour (37 miles per hour).

    The Persian Gulf is an arm of the Arabian Sea bordered by Iran, Iraq, Kuwait, Saudi Arabia, Qatar, Bahrain, the United Arab Emirates, and Oman. Vast deposits of petroleum in this region make the Persian Gulf strategically important. Middle Eastern countries depend on the gulf for trade and for access to the Indian Ocean. All countries that consume oil from the region, including the U.S., have a vital interest in keeping the gulf open to shipping.

    The Gulf of Aqaba is named after Aqaba, a large coastal city in Jordan. It was previously named the Gulf of Eilat, a large coastal city in Israel.

    Bridging the Gulf
    The Middle Eastern countries of Bahrain and Qatar have reached an agreement to build the world's longest oversea bridge, which will span 40 kilometers (25 miles) over the Persian Gulf. The bridge, which is expected to be completed by 2013, will cut the travel time between the two countries from five hours to 30 minutes!

  • Term Part of Speech Definition Encyclopedic Entry
    access Noun

    ability to use.

    agriculture Noun

    the art and science of cultivating the land for growing crops (farming) or raising livestock (ranching).

    Encyclopedic Entry: agriculture
    bay Noun

    body of water partially surrounded by land, usually with a wide mouth to a larger body of water.

    Encyclopedic Entry: bay
    border Verb

    to exist on the edge of a boundary.

    breeze Noun

    light wind or air current.

    canal Noun

    artificial waterway.

    coastline Noun

    outer boundary of a shore.

    commercial Adjective

    having to do with the buying and selling of goods and services.

    consume Verb

    to use up.

    crust Noun

    rocky outermost layer of Earth or other planet.

    Encyclopedic Entry: crust
    dam Noun

    structure built across a river or other waterway to control the flow of water.

    dead zone Noun

    area of low oxygen in a body of water.

    Encyclopedic Entry: dead zone
    delta Noun

    the flat, low-lying plain that sometimes forms at the mouth of a river from deposits of sediments.

    Encyclopedic Entry: delta
    drainage system Noun

    series of pipes, gutters, or other waterways used to carry off excess water.

    economic Adjective

    having to do with money.

    ecosystem Noun

    community and interactions of living and nonliving things in an area.

    Encyclopedic Entry: ecosystem
    enormous Adjective

    very large.

    export Verb

    to transport goods to another place for trade.

    good Noun

    object or service that serves a human need or want.

    gulf Noun

    portion of an ocean or sea that penetrates land.

    Encyclopedic Entry: gulf
    Gulf Stream Noun

    warm current that starts in the Gulf of Mexico and travels along the eastern coast of the U.S. and Canada before crossing the North Atlantic Ocean.

    harbor Noun

    part of a body of water deep enough for ships to dock.

    Encyclopedic Entry: harbor
    hurricane Noun

    tropical storm with wind speeds of at least 119 kilometers (74 miles) per hour. Hurricanes are the same thing as typhoons, but usually located in the Atlantic Ocean region.

    Hurricane Katrina Noun

    2005 storm that was one of the deadliest in U.S. history.

    import Verb

    to bring in a good or service from another area for trade.

    industry Noun

    activity that produces goods and services.

    inlet Noun

    small indentation in a shoreline.

    irrigate Verb

    to water.

    island Noun

    body of land surrounded by water.

    Encyclopedic Entry: island
    Middle East Noun

    region of southwest Asia and northeast Africa.

    Morning Glory Cloud Noun

    weather formation that results in a very large, fast-moving cloud over some shallow gulfs and bays.

    mouth Noun

    place where a river empties its water. Usually rivers enter another body of water at their mouths.

    Encyclopedic Entry: mouth
    nation Noun

    political unit made of people who share a common territory.

    Encyclopedic Entry: nation
    nutrient Noun

    substance an organism needs for energy, growth, and life.

    Encyclopedic Entry: nutrient
    ocean Noun

    large body of salt water that covers most of the Earth.

    Encyclopedic Entry: ocean
    oil deposit Noun

    natural accumulation of petroleum, usually underground or under the ocean floor.

    originate Verb

    to begin or start.

    penetrate Verb

    to push through.

    peninsula Noun

    piece of land jutting into a body of water.

    Encyclopedic Entry: peninsula
    petroleum Noun

    fossil fuel formed from the remains of ancient organisms. Also called crude oil.

    pollution Noun

    introduction of harmful materials into the environment.

    Encyclopedic Entry: pollution
    port Noun

    place on a body of water where ships can tie up or dock and load and unload cargo.

    Encyclopedic Entry: port
    portion Noun

    part of a whole.

    reduce Verb

    to lower or lessen.

    region Noun

    any area on Earth with one or more common characteristics. Regions are the basic units of geography.

    Encyclopedic Entry: region
    rift Noun

    break in the Earth's crust created by it spreading or splitting apart.

    river management Noun

    the art and science of controlling the flow, path, and power of rivers.

    sediment Noun

    solid material transported and deposited by water, ice, and wind.

    Encyclopedic Entry: sediment
    seep Verb

    to slowly flow through a border.

    shipping Noun

    transportation of goods, usually by large boat.

    storm Noun

    severe weather indicating a disturbed state of the atmosphere resulting from uplifted air.

    strait Noun

    narrow passage of water that connects two larger bodies of water.

    Encyclopedic Entry: strait
    strategic Adjective

    important part of a place or plan.

    subduction Noun

    process of one tectonic plate melting, sliding, or falling beneath another.

    swamp Noun

    land permanently saturated with water and sometimes covered with it.

    Encyclopedic Entry: swamp
    tectonic plate Noun

    massive slab of solid rock made up of Earth's lithosphere (crust and upper mantle). Also called lithospheric plate.

    threaten Verb

    to scare or be a source of danger.

    thrive Verb

    to develop and be successful.

    trade Noun

    buying, selling, or exchanging of goods and services.

    trading center Noun

    settlement or business area where goods and services are exchanged.

    trough Noun

    a gently sloping depression in the ocean floor.

    upwelling Noun

    process in which cold, nutrient-rich water from the bottom of an ocean basin or lake is brought to the surface due to atmospheric effects such as the Coriolis force or wind.

    Encyclopedic Entry: upwelling
    vary Verb

    to change.

    vast Adjective

    huge and spread out.

    vital Adjective

    necessary or very important.

    wetland Noun

    area of land covered by shallow water or saturated by water.

    Encyclopedic Entry: wetland