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Recruit Training Flight. Lesson 5 Part 3 Map Reading. Shape of the Land. On the OS Maps we have contour lines which show us the SHAPE of the land. This is important to know, as when looking for the best route, the shortest route might not always be the quickest.
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Recruit Training Flight Lesson 5 Part 3 Map Reading
Shape of the Land • On the OS Maps we have contour lines which show us the SHAPE of the land. • This is important to know, as when looking for the best route, the shortest route might not always be the quickest. • For example, sometimes it may take less time to walk round a hill than to go over the hill depending on the height. • The contour lines will show us the RELIEF or shape of the land so we can decide the best route.
Contours • Contours on the map are a way of representing height of the ground on your flat piece of paper. • On a 1:5000 OS map, the contours are every 10m • On a 1:2500 OS map, the contours are every 5m • Occasionally, the contours are marked with their heights to best aid working out the land shape. • We can tell the shape of the land by looking at the shapes of the contours and by looking at the direction the slopes.
At Point A walking to Point B – I am travelling DOWNHILL because the contour numbers are upside down if I orientate the map, ie I am looking DOWN the slope! At Point A walking to Point C – I am travelling UPHILL because the contour numbers are the correct way up if I orientate the map, ie I am looking UP the slope! A B C
Shape of the Land • Contours show us the shape of the land.
Slopes • Where contours are close together, the slope is Steep • Where they are further apart, the slope is gradual
Task • Draw what you think the slope of this hill will be like: 20 10 30 40 50
Spot Heights & Trig Points • On maps you sometimes get a height marked on which is not on a contour line. • This is a Spot Height. • A Trig Point is also a height at a particular point, but a Trip Point will have a physical marker on the ground and is marked in a Blue Triangle. Spot Height Trig Point
Although this route may look straight forward, have a look at the video of the route on the squadron website. • LINK
Contour Summary • Contour lines join areas of the same height. • The closer together a set of contour lines, the steeper the slope. • The further apart the contour lines, the shallower the slope. • On a 1:25,000 scale map, contour lines = 5m • On a 1:50,000 scale map, contour lines = 10m
Questions for You • A “Roamer” would be used in finding: • a. The direction of a track • b. The grid reference point • c. The average gradient • d. A relative bearing
Questions for You • What is the meaning of the two letters in a Grid Reference using the UK National Grid e.g. a Grid Reference of TL307624? • a. The point is located in one of the Grid squares with sides of 500Km • b. The point is located in one of the Grid squares with sides of 1Km • c. The point is located in one of the Grid squares with sides of 100Km • d. The point is located 30Km East and 62Km North of origins of the grid
Questions for You • In map reading, what does the word “relief” mean? • a. Hill shading • b. Layer tinting • c. The rise and fall of the land • d. Hachuring
Questions for You • What shape would the contours be for a spur? • a. Round • b. Elliptical • c. Hairpin • d. Straight
Questions for You • If you were to rotate the map so that the figures on the contour lines were the right way up, which way would you be looking? • a. Down the slope depicted by the contours • b. Up the slope depicted by the contours • c. Grid North • d. True North
Questions for You • What must there be between any two adjacent contour lines (on a map) which have different values? • a. Flat land • b. A slope • c. A ridge • d. A spur
Questions for You • If, by studying a map, you cannot be sure whether one place can be seen from another, what can you do to decide? • a. Draw a cross-section of the land between them • b. Calculate the gradient between them • c. Calculate the mean contour line • d. Calculate the height of the land by reference to the spot heights in the area
By The End of the Lesson • You will be able to find a point indicated by a 6 figure grid reference; • You will be able to give a 6 figure grid reference for a point on a standard OS map; • You will be able to look at gradients on a map and be able to visualise the land form; • You will have a good knowledge of OS style maps, map scales, symbols and features.
Look Ahead • Your next lesson will be on Initial Expedition Training