• oxbow lake
    The meander in this river may become an oxbow lake as the river takes a shortcut and cuts off the curves.

    Photograph by Jeffrey Wickett, MyShot

    Billabong
    In Australia, oxbow lakes are called billabongs. A billabong is the setting for the unofficial national anthem of Australia, Waltzing Matilda.

    An oxbow lake starts out as a curve, or meander, in a river. A lake forms as the river finds a different, shorter, course. The meander becomes an oxbow lake along the side of the river.

    Oxbow lakes usually form in flat, low-lying plains close to where the river empties into another body of water. On these plains, rivers often have wide meanders.

    Meanders that form oxbow lakes have two sets of curves: one curving away from the straight path of the river and one curving back. The corners of the curves closest to each other are called concave banks. The concave banks erode over time. The force of the rivers flowing water wears away the land on the meanders concave banks.

    The banks opposite the concave banks are called convex banks. The opposite of erosion happens here. Silt and sediment build up on convex banks. This build-up is called deposition.

    Erosion and deposition eventually cause a new channel to be cut through the small piece of land at the narrow end of the meander. The river makes a shortcut. Oxbow lakes are the remains of the bend in the river.

    Oxbow lakes are stillwater lakes. This means that water does not flow into or out of them. There is no stream or spring feeding the lake, and it doesnt have a natural outlet. Oxbow lakes often become swamps or bogs, and they often dry up as their water evaporates.

    Oxbow lakes can be rich wildlife habitats. Along the Amazon River in South America, oxbow lakes are common and their still waters provide a unique habitat for plants and wildlife. Giant river otters frequently live in the Amazons oxbow lakes, and feed on about 5 kilograms (11 pounds) of fish per day.

    People often create oxbow lakes. The Mississippi River is shorter now than it was in the 19th century, for instance, because engineers have cut off hundreds of meanders. This created hundreds of oxbow lakes. These lakes eventually dried up to create acres of land for farming, housing, and industry.

    An oxbow lake gets its name from the U-shaped collar placed around an oxs neck to which a plow is attached. It can also be called a horseshoe lake, a loop lake, or a cutoff lake.

  • Term Part of Speech Definition Encyclopedic Entry
    billabong Noun

    Australian name for an oxbow lake.

    bog Noun

    wetland of soft ground made mostly of decaying plant matter.

    channel Noun

    waterway between two relatively close land masses.

    Encyclopedic Entry: channel
    concave bank Noun

    the outside bank of a rounded bend in a river.

    convex bank Noun

    inside bank of a rounded bend in a river.

    deposition Noun

    process of silt and sediment building up in an area.

    engineer Noun

    person who plans the building of things, such as structures (construction engineer) or substances (chemical engineer).

    erode Verb

    to wear away.

    evaporate Verb

    to change from a liquid to a gas or vapor.

    farming Noun

    the art, science, and business of cultivating the land for growing crops.

    fish Noun

    aquatic animals with gills, and usually fins and scales.

    giant river otter Noun

    aquatic otter up to six feet long, native to the Amazon, Orinoco, and La Plata rivers of South America.

    habitat Noun

    environment where an organism lives throughout the year or for shorter periods of time.

    Encyclopedic Entry: habitat
    housing Noun

    shelters where people live.

    industry Noun

    activity that produces goods and services.

    lake Noun

    body of water surrounded by land.

    meander Noun

    large curve in a lake or stream.

    ox Noun

    large bovine often used for hauling heavy loads.

    oxbow lake Noun

    lake formed from an abandoned bend in a river.

    Encyclopedic Entry: oxbow lake
    plain Noun

    flat, smooth area at a low elevation.

    Encyclopedic Entry: plain
    plow noun, verb

    tool used for cutting, lifting, and turning the soil in preparation for planting.

    river Noun

    large stream of flowing fresh water.

    Encyclopedic Entry: river
    sediment Noun

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

    Encyclopedic Entry: sediment
    silt Noun

    small sediment particles.

    Encyclopedic Entry: silt
    spring Noun

    small flow of water flowing naturally from an underground water source.

    still-water lake Noun

    body of water with no streams or springs flowing into or out of it.

    stream Noun

    body of flowing water.

    Encyclopedic Entry: stream
    swamp Noun

    land permanently saturated with water and sometimes covered with it.

    Encyclopedic Entry: swamp
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