Transcript oxbow lake
A landform is any natural formation of rock and dirt, found on Earth. A landform can be as large as a mountain range, or as small as a hill. “Geomorphological feature” U-shaped Valley V-shaped Valley Cave Atoll What is an arichpelago? An archipelago is a chain or cluster of islands. Archipelagos are usually found in the open sea; less commonly, a large land mass may neighbor them, What is an ocean? ocean* -- a great expanse of salt water. What is an island? • island -- a piece of land completely surrounded by water What is an atoll? • atoll - a ring (or partial ring) of coral that forms an island in an ocean or sea. Typically, the volcanic mountain that rose up out of the sea was covered by coral just off the shore of the island. As wind, rain, and other forms of weather eroded the volcanic mountain, the coral would still grow at the boundary between land and ocean. When erosion completely wiped out the island, all that remains is the ring of coral around what used to be an island. What is a cape? • cape -- A point or head of land projecting into a body of water What is an isthmus? • isthmus* -- a narrow strip of land, like a bridge, connecting two larger strips of land What is a bay? • bay -- an area of sea partially enclosed by land, smaller than a gulf What is a beach? • • A beach is a landform along the shoreline of a body of water. It usually consists of loose particles which are often composed of rock, such as sand, gravel, shingle, pebbles, or cobble. The particles of which the beach is composed can sometimes instead have biological origins, such as shell fragments or coralline algae fragments. Beaches often occur along coastal areas, where wave or current action deposits and reworks sediments. What is a sandbar? • A shoal or sandbar (also called sandbank) is a somewhat linear landform within or extending into a body of water, typically composed of sand, silt or small pebbles. A bar is characteristically long and narrow (linear) and develops where a stream or ocean current promote deposition of granular material, resulting in localized shallowing (shoaling) of the water. Bars can appear in the sea, in a lake, or in a river. What is a peninsula? • peninsula* -- a narrow stretch of land surrounded on three sides by water. What is a sea? sea* -- a relatively large body of water, either part of an ocean that is partially surrounded by land (the Caribbean Sea), or a body of water that is completely landlocked (the Caspian Sea is seen in the image above) What is a sound? • sound* -- a long passage of water connecting two larger bodies What is a river? •A long body of water that flows across the land. •The Nile River is the longest river in the world •The Amazon River is in Brazil. •The Mississippi River is the longest river in the United States. What is a river source ? • river source - beginning of a river What is a river mouth ? • river mouth -- the place where a river empties into a larger body of water What is a delta? • delta -- a place at the river's mouth, where the river splits into many different sections, forming a marshy triangle What is a tributary? • tributary* -- A stream that flows into a larger stream or other body of water What is a flood plain ? • flood plain -- A plain bordering a river and subject to flooding. What is a pond? • pond is a body of water smaller than a lake. What is a gulf? • gulf* -- A large area of a sea or ocean partially enclosed by land What is a strait? • strait -- A narrow channel of water joining two larger bodies of water (usually narrower than a sound). What is a marsh? • marsh -- An area of soft, wet, low-lying land, with grassy vegetation, often forming a transition zone between water and land. What is a swamp? • swamp -- A lowland region saturated with water. What is a lake? • lake* -- A large inland body of fresh water or salt water What is an oxbow lake ? • An oxbow lake is a U-shaped lake water body formed when a wide meander from the mainstream of a river is cut off to create a lake. This landform is called an oxbow lake for the distinctive curved shape that results from this process. What is meander? • meander in general is a bend in a sinuous watercourse, also known as an oxbow loop, or simply an oxbow. What is a basin? basin* -- A large, bowl-shaped depression in the surface of the land, often drained by a single river What is a glacier? • glacier -- A huge mass of ice slowly flowing over a land mass What is a moraine? • moraine* -- An accumulation of boulders, stones, or other debris carried and deposited by a glacier What is a fjord? • fjord - a long, narrow sea inlet that is bordered by steep cliffs What is a plain? • Plains are broad, nearly level stretches of land that have no great changes in elevation. Plains are generally lower than the land around them; they may be found along a coast or inland. What is a steppe? • steppe -- A vast grass-covered plain. What is a dune? • dune is a hill or a ridge made of sand. Dunes are shaped by the wind, and change all the time. What is a alluvial fan ? • An alluvial fan is a fan-shaped deposit formed where a fast flowing stream flattens, slows, and spreads typically at the exit of a canyon onto a flatter plain. What is an oasis? • oasis -- A fertile or green spot in a desert or wasteland What is a hill? • hill* -- a small elevation in the earth's surface What is a cave? • cave -- simply a hole in the ground, most commonly in a rock that is porous and readily eroded from within. What is a butte? A butte is an isolated hill with steep, often vertical sides and a small flat top, smaller than mesas, plateaus, and tables. What is a canyon? • canyon -- A narrow chasm with steep cliff walls, cut into the earth by running water What is a mesa? • mesa -- A broad, flat-topped elevation with one or more clifflike sides What is a plateau? plateau -- an elevated level expanse of land; a tableland. What is a U-shaped valley? A valley carved by glaciers, or glacial valley, is normally Ushaped. The valley becomes visible upon the recession of the glacier that forms it. When the ice recedes or thaws, the valley remains, often littered with small boulders that were transported within the ice. Floor gradient does not affect the valley's shape, it is the glacier's size that does. Continuously flowing glaciers - especially in the ice age - and large sized glaciers carve wide, deep incised valleys. What is a V-shaped valley? A valley formed by flowing water, or river valley, is usually Vshaped. The exact shape will depend on the characteristics of the stream flowing through it. Rivers with steep gradients, as in mountain ranges, produce steep walls and a narrow bottom. Shallower slopes may produce broader and gentler valleys, but in the lowest stretch of a river, where it approaches its base level, it begins to deposit sediment and the valley bottom becomes a floodplain. What is a continental divide ? A continental divide is a line of elevated terrain which forms a border between two watersheds such that water falling on one side of the line eventually travels to one ocean or body of water, and water on the other side travels to another, generally on the opposite side of the continent. What is a mountain? • The highest kind of land. They are caused when two tectonic places collided. • Types of mountains: Folded, Unwarped, & FaultBlock What are Folded Mountains ? Folded Mountains are made from rock layers that were squeezed from opposite sides causing the rock layers to fold What are Unwarped Mountains ? Unwarped Mountains are made when the crust was pushed upward by forces inside the Earth What are Fault-Block Mountains ? Fault-Block Mountains are made of huge tilted blocks of rocks that are separated from surrounding rocks by faults. A fault is a huge crack in the rocks. What is a volcano? volcano -- An opening in the earth's crust through which molten lava, ash, and gases are ejected. Types of volcanoes: Shield, Strato, Dome, Cinder Cone, and Rhyolite Caldera Complex Shield Volcano • Shield Volcano - A gently-sloping volcano that emits mostly basaltic lava (very fluid lava) that flows in longlasting, relatively gentle eruptions - explosions are minimal. Shield volcanoes can be very big Composite or Strato Volcano • Composite or Strato Volcano - A steep-coned volcano that explosively emits gases, ash, pumice, and a small amount of stiff, silica lava (called rhyolite). This type of volcano can have eruptions accompanied by lahars -- deadly mudflows. Most volcanoes on Earth are of this type. Stratovolcanoes kill more people than any other type of volcanoes - this is because of their abundance on Earth and their powerful mudflows Lava Dome Volcano • Lava Dome - A bulbous (rounded) volcano that forms when very viscous lava barely flows Cinder Cone Volcano • Cinder Cone - A cone-shaped volcano whose steep sides are formed by loose, fragmented cinders that fall to the Earth close to the vent. The lava flows through a single vent that is usually only up to about 1,000 feet tall. There is usually a bowl-shaped crater at the top. As the gas-filled lava erupts into the air, the lava fragments into pieces and forms cinders. Rhyolite Caldera Complex Volcano • Rhyolite Caldera Complex - these are the most explosive volcanoes. They do not look like common volcanoes -- after an eruption, the result is a caldera (crater) caused when the area around the vent collapses.