Dizzy & The Water Wheel - Glossary

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Alluvium: Sometimes called silt it is made up of the fine soil and debris left after a river floods or deposits its load.

Attrition: As the rocks and pebbles are being swept along they bang against each other and they slit up or little bits get knocked off, making them smaller and smaller. This also has the effect of smoothing and rounding the particles too.

Braided river: Where a river is forced to divide into several channels with banks or islands separating the channels.

Catchment: The area of land drained by a river and its tributary streams. Sometimes referred to as the 'drainage basin'.

Current: The flow of the river.

Corrasion: The bits of rock and sand in the river rub along the banks, wearing it down and knocking more particles into the water flow.

Corrosion: The rainwater that flows into the river all along its length is very slightly acid. This acid very slowly dissolves minerals such as calcium carbonate in limestone.

Deposition: The laying down of material by the river usually where the speed of the water decreases.

Erosion: The wearing away and removal of rock, stones and soil by the river.

Flood: Where a river overspills its banks and spreads out on the valley floor.

Floodplain: The floodplain is the area of flat ground alongside the river. When the river floods this area is covered in water. As the water flows away at the end of the flood the nutrients in the water are left behind, making the grounds of the floodplain very fertile.

Gorge: A steep sided valley that has almost vertical sides which cuts into the landscape like a narrow channel.

Hydraulic action: This is when the water simply hits part of the riverbank so hard it sweeps it away.

Interlocking spurs: As the river cuts a valley it will often curve due to softer spots in the rock or cracks etc. These curves cut out a set of interlocking teeth like spurs in the hill.

Levees: High mounds of silt, which have deposited on the banks of a river during flooding and have frequently been increased by man to protect the floodplain.

Meander: A meander is the name for the natural curves in a river. As a river flows, the current increases any curve in its course. On the outside of the curve the water velocity, and therefore the erosion caused by the current is greatest. Here the river cuts into the outside bank, producing a river cliff and the river's deepest points, pools. On the curve's inside the current is slow and deposits any transported material, building up a gentle slip-off slope. As each meander migrates in the direction of its river cliff, the river gradually changes its course across the flood plain. A loop in a river's flow may become so far away from the straight route that it becomes cut off from the normal course and forms an oxbow lake.

Oxbow lake: Curved lake found on the flood plain of a river. Oxbows are caused by the loops of meanders being cut off at times of flood and the river changing its route so that it flows along a shorter course.

Plunge pool: A hollow at the base of a waterfall creating a deep pool.

Rapids: Where boulders or rocks create turbulent water by breaking the smooth river flow.

River Source: This is where the river originates. It is usually on high ground and can be a place where runoff collects or where a spring surfaces.

River cliff: Steep slope forming the outer bank of a meander. It is formed by the undercutting of the river current, which at its fastest when it sweeps around the outside of the meander.

River mouth: The end of a river where it enters the sea or a lake.

Slip off slope: Gentle slope forming the inner bank of a meander. It is formed by the deposition of fine silt, or alluvium, by slow-flowing water.

Saltation: Little pieces of gravel and sand bounce along the riverbed in a series of short hops as the river picks them up then drops them again because they are not light enough to be kept afloat.

Suspension: Tiny grains of sand are light enough to actually be kept in midflow and washed along with the water.

Solution: When a weak acid in water dissolves rock, such as limestone.

Traction: This is when the force of the water simply rolls large rocks along the riverbed. The river usually only has this much force in times of flood.

Transportation: The movement of eroded material by the river.

Tributary: A small stream or river which flows into a larger river.

Undercutting: Where the river is flowing fast around an outside bend and erodes the bank to create a steep bank. The opposite of the slip-off slope.

V-Shaped valleys: When there is a large amount of rain on the hills the river can often gain the force to push large boulders along the river bed, which causes the river to cut deep into the hill. This is called vertical erosion causing deep valleys with steep sides.

Water Cycle: The never-ending movement of water between the sea, the land and the air.

Watershed: The boundary between two river drainage basins or catchments.

Waterfalls: Waterfalls are created when the ground suddenly changes for some reason. This can be because of earthquakes or ice movements creating a drop, or sometimes the water creates its own drop when it meets a band of softer rock and erodes down into that after flowing down a layer of slower eroded hard rock. The soft rock eroded at the bottom of the waterfall is eroded deeper and deeper so that it forms a plunge pool.

Task: Dizzy the Water Droplet

Write a story about an imaginary water droplet and its journey from a cloud in the sky, into a river and all the way down to the sea.

The journey should include the different processes and features that Dizzy would see, using the correct geographical term to describe them. The terms you use from the 'water wheel' should be highlighted and the story may be illustrated.