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Important vocabulary Word Meaning Carnivore Any animal that feeds on flesh; Tyrannosaurus Rex was a large carnivore! Insectivorous plants are also considered carnivores. Herbivore Any animal that feeds chiefly on grass and other plants Detritivore An organism (as an earthworm or a fungus) that feeds on dead and decomposing organic matter RIVERS Alluvium A deposit of clay, silt, sand, and gravel left by flowing streams in a river valley or delta, typically producing fertile soil. (The picture here shows farming in Ladakh, India) Backwater A small, generally shallow body of water attached to the main channel with little or no current of its own pushed back by a dam or current. (The picture here shows the Pearl River backwater in Mississippi) Bedload The material carried by a river by being bounced or rolled along its bed Image Bore Confluence Delta A high wave caused by the surge of a flood tide upstream in a narrowing estuary or by colliding tidal currents. Traveling upstream about two or three times faster than the normal tidal current, a bore usually is characterized by a well-defined front of one or several waves, often breaking, followed by the bore's main body, which rises higher than the water level at its front. The point at which two or more rivers meet. (The picture here shows Roman River and River Colne in Wivenhoe, Essex) When a river reaches a lake or the sea the water slows down and loses the power to carry sediment. A delta is a large, silty area at the mouth of a river at which the river splits into many different slowflowing channels that have muddy banks. New land is created at deltas. Deltas are often triangularshaped, hence the name (the Greek letter 'delta' is shaped like a triangle). Some deltas are so large that people can live on them. The Nile delta is a very important farming area in Egypt. Delta Plain Deltas have a fairly flat section called a delta plain that is above water. The river cuts many small channels through the delta plain. These channels are called distributaries. New sections of delta build up at the mouths of the distributaries. Deposition The process by which sediments are laid down in new locations Discharge The volume of water passing a certain point along a stream or river in a given period Downstream The direction that a river or stream is flowing Eddy current A contrary turbulence that creates circular upstream currents behind rocks and other obstructions and along the edges of a stream or river channel. Erosion The removal or wearing away of soil or rock by water, wind, or other agents. Estuary An estuary is the area where a river meets the sea or ocean, where fresh water from the river meets salt water from the sea Flood A flood is a great flowing or overflowing of water onto land that is not usually submerged. A flood happens when too much rain, brought by storms and strong winds, falls and cannot be absorbed by the soil. Rivers burst their banks and the water spills onto the land. Strong winds blowing across the sea make huge waves that surge onto the land and flood coastal areas. Flood Plain A nearly flat plain along the course of a stream or river that is naturally subject to flooding. Gorge Over time rivers can cut through bedrock. Rivers flowing over soft sedimentary rocks can cut deep gorges and canyons. (Gorge du Verdon) Meander A bend in a river. The outside of the meander has the fastest flow and deepest water. Mouth Where the river ends its journey and joins a lake or ocean Mudflat Low-lying muddy land that is covered at high tide and exposed at low tide. Oxbow lake An oxbow lake is a stagnant lake that is formed alongside a winding river when the river changes path because of soil erosion, leaving an abandoned stream channel, cut off from the rest of the river Plunge Pool A depression at the base of a waterfall created by the falling water scouring where it lands. Riparian Plunge pools are formed under the force of a natural source, such as a waterfall or rapids. The swirling water, sometimes carrying rocks within it, erodes the riverbed into a basin, often featuring irregular and rough sides. Plunge pools can remain after the waterfall has ceased to exist or the stream has been diverted. An area of land and vegetation adjacent to a stream that has a direct effect on the stream. This includes woodlands, vegetation, and floodplains. Rapids Found where the river meets a band of resistant rock and usually precede a waterfall. Riffle A stretch of river/stream that is characterized by shallow, fast moving water broken by the presence of rocks and boulders. Riverbank The land alongside a body of water. River basin A river basin is an area of land drained by a river and its tributaries. Riverbed The bottom of a body of water. River channel A channel is an area that contains flowing water confined by banks. Runoff River channels vary greatly in cross-sectional size and shape but are usually bounded by defined banks which separate the channel from the floodplain or valley side. Runoff is water that drains into a river (or other body of water) from uncontrolled streams, drains, or sewage lines. There is runoff from agricultural irrigation water, snowmelt, storms, etc. It eventually flows into lakes and the ocean. Salination (see transportation) Solution (see transportation) Source Where the river starts its journey. NB – As you can see from the image to the source of the River Thames – it isn’t always obvious! Suspension (See transportation) Traction (See transportation) Transportation Flowing water moves eroded material downstream in different ways Solution - minerals are dissolved in the water and carried along in solution. Suspension - fine light material is carried along in the water. Saltation - small pebbles and stones are bounced along the river bed. Traction - large boulders and rocks are rolled along the river bed A river or stream that flows into another stream, river, or lake. Tributary A smaller river that joins a larger one Upstream In the opposite direction to the way a river or stream flows Velocity The speed that the river flows Waterfall A waterfall is a sudden drop in a river as it flows over a rock cliff. This happens when the river passes from a layer of hard rock to a layer of softer rock, and the water erodes away the softer rock. Watershed A watershed describes an area of land that contains a common set of streams and rivers that all drain into a single larger body of water, such as a larger river, a lake or an ocean. The Mississippi River watershed is an enormous watershed. All the tributaries to the Mississippi that collect rainwater eventually drain into the Mississippi, which eventually drains into the Gulf of Mexico. Rainwater that falls on more than half of the United States subsequently drains into the Mississippi. Water Cycle Water Cycle The water cycle the natural cycle in which the sun's energy evaporates water into the atmosphere, and the water vapour condenses, returning to the Earth as precipitation (rain, snow, sleet, etc.) Atmosphere The earth is surrounded by a layer of gases called the atmosphere. The atmosphere is very important to life on Earth and does many things to help protect life and help life to survive. Cloud A mass of tiny droplets of water that condensed from the air Condensation The forming of tiny droplets of water as water vapour cools. Water vapour in the air is changed into liquid water. Condensation is crucial to the water cycle because it is responsible for the formation of clouds. Evaporation Process in which the sun's heat turns liquid water into water vapour. Evaporation is the process by which water changes from a liquid to a gas or vapour. Evaporation is the primary pathway that water moves from the liquid state back into the water Ground water Water found beneath Earth's surface Infiltration The downward movement of water from the land surface into the soil or porous rock. Ground water begins as precipitation. Once water infiltrates the soil it can move vertically and horizontally through the soil. Precipitation The falling to earth of any form of water (rain or snow or hail or sleet or mist). Only 10% of water evaporated falls as precipitation. Surface water Water contained in places such as lakes, ponds, rivers, streams, and reservoirs Transpiration The release of water from plant leaves in to the atmosphere Water vapour The gas formed when water evaporates and the changes back in to a liquid – forming clouds.