• sediment
    Sediment that is light enough to be carried by water without touching the stream bed is called suspended sediment, and is visible as cloudy or milky areas of water.

    Photograph by Mike Kelly, MyShot

    Dregs
    Sediment can accumulate in tea and coffee! The tiny materials left at the bottom of coffee mugs and teacupsthe remains of coffee grounds and tea leavesare a type of sediment called dregs.

    Sediment is solid material that is moved and deposited in a new location. Sediment can consist of rocks and minerals, as well as the remains of plants and animals. It can be as small as a grain of sand or as large as a boulder.

    Sediment moves from one place to another through the process of erosion. Erosion is the removal and transportation of rock or soil. Erosion can move sediment through water, ice, or wind.

    Water can wash sediment, such as gravel or pebbles, down from a creek, into a river, and eventually to that river's delta. Deltas, river banks, and the bottom of waterfalls are common areas where sediment accumulates.

    Glaciers can freeze sediment and then deposit it elsewhere as the ice carves its way through the landscape or melts. Sediment created and deposited by glaciers is called moraine.

    Wind can move dirt across a plain in dust storms or sandstorms. Sand dunes are made of rocky sediment worn down by wind and collision with other sand particles.

    Sediment is important because it often enriches the soil with nutrients. Areas rich in sediments are often also rich in biodiversity. Sedimentary soil is usually better for farming. Deltas and river banks, where much sediment is deposited, are often the most fertile agricultural areas in a region.

    For thousands of years, the Nile River flooded yearly and brought with it 4 million metric tons (4.4 million short tons) of nutrient-rich sediment. The banks of the Nile are still Egypt's richest agricultural land.

    Sedimentary Rock

    Over millions of years, layers of sediment may build up and harden into sedimentary rock. Some of the many forms of sedimentary rock include sandstone, rock salt, and coal.

    Sandstone forms as sand hardens. For centuries, sandstone has been mixed with sticky cement to form concrete. Concrete is an important construction material used for many buildings and roads.

    Rock salt, also known as halite, forms as oceans evaporate. Oceans are made of salt water. When the water enters the atmosphere as vapor, it leaves the salt behind. The Bonneville Salt Flats, in the U.S. state of Utah, are flat desert areas covered by a layer of rock salt sediment. Lake Bonneville, the ancient sea that once covered the area, has long since evaporated.

    Coal is a sediment that is made up of hardened plant debris. Coal, present on every continent except Antarctica, is found on the sites of former swamps and wetlands.

  • Term Part of Speech Definition Encyclopedic Entry
    accumulate Verb

    to gather or collect.

    agriculture Noun

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

    Encyclopedic Entry: agriculture
    ancient Adjective

    very old.

    atmosphere Noun

    layers of gases surrounding a planet or other celestial body.

    Encyclopedic Entry: atmosphere
    bank Noun

    a slope of land adjoining a body of water, or a large elevated area of the sea floor.

    biodiversity Noun

    all the different kinds of living organisms within a given area.

    Encyclopedic Entry: biodiversity
    boulder Noun

    large rock.

    cement Noun

    hard material used as a building material or a binding agent for stronger building materials such as concrete.

    coal Noun

    dark, solid fossil fuel mined from the earth.

    concrete Noun

    hard building material made from mixing cement with rock and water.

    continent Noun

    one of the seven main land masses on Earth.

    Encyclopedic Entry: continent
    creek Noun

    flowing body of water that is smaller than a river.

    debris Noun

    remains of something broken or destroyed; waste, or garbage.

    delta Noun

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

    Encyclopedic Entry: delta
    deposit Verb

    to place or deliver an item in a different area than it originated.

    desert Noun

    area of land that receives no more than 25 centimeters (10 inches) of precipitation a year.

    Encyclopedic Entry: desert
    dirt Noun

    dry earth or soil.

    dune Noun

    a mound or ridge of loose sand that has been deposited by wind.

    Encyclopedic Entry: dune
    dust storm Noun

    weather pattern of wind blowing dust over large regions of land.

    enrich Verb

    to supply with valuable material.

    erosion Noun

    act in which earth is worn away, often by water, wind, or ice.

    Encyclopedic Entry: erosion
    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.

    fertile Adjective

    able to produce crops or sustain agriculture.

    flood Verb

    to overflow or cover in water or another liquid.

    glacier Noun

    mass of ice that moves slowly over land.

    Encyclopedic Entry: glacier
    gravel Noun

    small stones or pebbles.

    halite Noun

    natural mineral form of salt (sodium chloride.) Also called rock salt.

    landscape Noun

    the geographic features of a region.

    Encyclopedic Entry: landscape
    mineral Noun

    inorganic material that has a characteristic chemical composition and specific crystal structure.

    moraine Noun

    material, such as earth, sand, and gravel, transported by a glacier.

    Encyclopedic Entry: moraine
    Nile River Noun

    (5,592 kilometers/3,473 miles) river in East Africa.

    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
    particle Noun

    small piece of material.

    pebble Noun

    very small, rounded rock.

    plain Noun

    flat, smooth area at a low elevation.

    Encyclopedic Entry: plain
    remains Noun

    materials left from a dead or absent organism.

    river Noun

    large stream of flowing fresh water.

    Encyclopedic Entry: river
    rock Noun

    natural substance composed of solid mineral matter.

    rock salt Noun

    natural mineral form of salt (sodium chloride.) Also called halite.

    sand Noun

    small, loose grains of disintegrated rocks.

    sandstone Noun

    rock formed by grains of sand.

    sandstorm Noun

    wind storm that blows great amounts of sand into the air.

    sea Noun

    large part of the ocean enclosed or partly enclosed by land.

    Encyclopedic Entry: sea
    sediment Noun

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

    Encyclopedic Entry: sediment
    sedimentary rock Noun

    rock formed from fragments of other rocks or the remains of plants or animals.

    soil Noun

    top layer of the Earth's surface where plants can grow.

    swamp Noun

    land permanently saturated with water and sometimes covered with it.

    Encyclopedic Entry: swamp
    vapor Noun

    visible liquid suspended in the air, such as fog.

    waterfall Noun

    flow of water descending steeply over a cliff. Also called a cascade.

    Encyclopedic Entry: waterfall
    wetland Noun

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

    Encyclopedic Entry: wetland
    wind Noun

    movement of air (from a high pressure zone to a low pressure zone) caused by the uneven heating of the Earth by the sun.

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