The Upper Course of a River

Transcription

1 The Upper Course of a River I. Introduction A river is split along the long profile into three different sections; the upper, middle and lower course. As GCSE students you are expected to know the characteristics of each course, the processes carried out by the river and the landforms created. This worksheet looks at the upper course; the section of the river nearest to the source. 1. The long profile of a river The image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again. Upper course Middle course Lower course II. Characteristics of the upper course Characteristics simply means what does it look like?. The upper course is on high land that is steep, this means that the river water is running quickly. The river channel is narrow, not very deep and runs in a reasonably straight line.

2 The image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again. You might be asked to identify the upper course from an OS map extract. This is easy to do. The contour lines (narrow orange lines that show height on a map) will be close together, any numbers showing height will be large (probably in the hundreds) and the river itself will be shown by a narrow blue line.

3 1. Upper course on an OS map III. Processes the river is carrying out Processes are the work that is being done by the river. Remember that the land is steep and therefore the water is moving quickly. Water that is moving quickly has more energy, water with lots of energy erodes the land. In the upper course the main type of erosion is vertical. This means that it is eroding downwards into the land. (Erode = when the earth is worn away, in this case by the acton of water) There are 4 different processes of erosion and you need to learn them off by heart. 1. Hydraulic action This is the action of the water itself. As it moves through the river channel it will force its way into small cracks, this will compress air in the cracks and cause small pieces of earth to break away. 2. Abrasion The moving water carries in it small bits of sand and earth. The water throws these bits of sand at the walls of the river channel, this rubs away more earth. The amount of sand and

4 earth carried by a river is known as its load. The greater the load of a river the more abrasion there will be. Abrasion is also sometimes known as corrasion. 3. Attrition Attrition is when small pebbles and rocks carried within the river bump into each other. This gradually wears away the rough edges of the pebbles and leaves them smooth. 4. Corrosion Corrosion is when material gets dissolved into the water. A good example is limestone. DO NOT confuse this with corrasion note the different spelling. IV. Landforms created by the river The landforms made by the river in the upper course are erosional. The main ones that you need to learn are: Rapids V shaped valley Waterfalls In a GCSE examination you may be asked to identify one of these features from an image or an OS map extract and then explain how it has been formed by the river. The next work sheet will look at how these landforms are made. You are often given the opportunity in these questions to draw a diagram. You must remember that a diagram alone will not get you many marks. You must include detailed labels to show you understand the processes taking place.

5 1. The upper course of the river is... a) near the mouth of the river b) near the source of the river c) in the middle of the river d) another name for a river channel? MCQ 2. The land in the upper course is... a) mostly flat b) sometimes steep but not very c) generally steep d) dependent on the river, sometimes it is flat and sometimes steep? 3. The river itself in the upper course is... a) narrow and slow moving b) deep, wide and fast moving c) narrow, shallow and fast moving d) narrow, shallow and slow moving? 4. On an OS map extract the upper course of the river will be shown by... a) high land and contour lines that are close together b) high land and few contour lines that are far apart c) contour lines that are close together and a wide blue line to show the river d) a narrow line to show the river and low land?

6 5. Attrition is... a) a type of landform being made by the river b) erosion caused by the action of the water c) when pebbles and small rocks in the river bump into each other d) when the rock is dissolved by water? 6. Rock being dissolved by water is called... a) corrasion b) abrasion c) solution d) corrosion? 7. Hydraulic action is... a) when bits of sand and earth carried in the water rub away at the river channel b) the action of the water itself eroding the land c) a type of landform made by the river d) when the rock is dissolved by river water? 8. The load of a river is... a) the amount of water in it b) the name of a landform made by the river c) a type of erosion d) the amount of earth, sand and sediment that a river carries?

7 9. Corrasion is another term for... a) hydraulic action b) abrasion c) corrosion d) attrition? 10. Some of the landforms found in the upper course of a river are... a) V shaped valleys and meanders b) meanders and waterfalls c) rapids and V shaped valleys d) waterfalls and deltas? Answers 1 = b, 2 = c, 3 = c, 4 = a, 5 = c, 6 = d, 7 = b, 8 = d, 9 = b, 10 = c.