A map represents part of the Earth's surface using a reduced scale and selected symbols. The scale relates a distance on the map to the corresponding distance on the ground. A representative fraction such as 1:50,000 means that one unit on the map equals 50,000 of the same units on the ground. Because the ratio uses identical units, it can be converted into centimetres, metres or kilometres as required.
At 1:50,000, one centimetre represents 50,000 centimetres, which is 500 metres or 0.5 kilometres. A road measuring six centimetres on that map therefore covers three kilometres if measured along the correct route. For a curved route, use a thread or a sequence of short measurements rather than measuring only the straight line between its endpoints. Straight-line distance and route distance answer different questions.
A large-scale map shows a smaller area with more detail than a small-scale map. Compare the fractions themselves: 1:25,000 is a larger scale than 1:250,000 because one twenty-five-thousandth is larger than one two-hundred-and-fifty-thousandth. The term does not that the denominator is larger. A linear scale remains useful if a map is enlarged or reduced together with the scale bar.
Direction can be described using compass points or bearings. A whole-circle bearing is measured clockwise from north from 000° to 360°. East is 090°, south is 180° and west is 270°. State the starting point when describing a bearing. The bearing of B from A is measured at A; reversing the journey changes the bearing by 180°, adjusted to remain within a full circle.
Contours join points of equal elevation. Closely spaced contours indicate a steep slope, while widely spaced contours indicate a gentler slope, assuming the same contour interval. Contour values usually increase toward a hilltop and decrease into a depression, which may require additional map markings. Read the legend and contour interval before drawing conclusions. In a calculation, show the scale conversion and units; in a description, support the conclusion with map evidence rather than merely naming a landform.
Choosing a scale and converting units
A large-scale map shows a smaller area in greater detail than a small-scale map, when the terms refer to representative fractions. Thus 1:25,000 is larger scale than 1:250,000 because each map centimetre covers less ground. The denominator alone can mislead: a larger denominator means a smaller representative fraction. A statement scale expresses the relationship in words, while a linear scale uses a marked bar. If a map is enlarged or reduced, a printed representative fraction becomes incorrect unless revised, whereas a scale bar resized with the map still represents the same ground distance.
For distance, measure the map line and multiply by the scale factor, keeping units identical before converting. At 1:100,000, 3.5 cm represents 350,000 cm, or 3.5 km. For area, square the linear factor. If 1 cm represents 2 km, then 1 cm² represents 4 km², not 2 km². Estimate irregular areas using a grid and an explicit rule for partial squares. The estimate depends on grid size and boundary interpretation, so report reasonable precision rather than many unjustified decimal places.
Bearings, direction and position
A whole-circle bearing is measured clockwise from north, from 000° to 360°. East is 090°, south is 180° and west is 270°. To find a reverse bearing, add 180° if the original is below 180°, or subtract 180° if it is above 180°. A bearing of 065° therefore reverses to 245°. Check that north is identified correctly on the map and that the protractor is placed at the starting point. A direction from A to B is not the same as one from B to A.
Grid references locate features using eastings first and northings second. A four-figure reference identifies a grid square, while a six-figure reference estimates a more precise position within that square. Work across the map before moving up. measures angular distance north or south of the equator, while measures angular distance east or west of the prime meridian. These global coordinates are not interchangeable with a local rectangular grid. State the coordinate system when giving a location rather than assuming that two numbers always the same thing.
Contours, slopes and profiles
A contour joins points at the same elevation above a stated datum. The vertical interval is the elevation difference between adjacent contour lines. Closely spaced contours usually indicate steep slopes, and widely spaced contours indicate gentler slopes, provided the interval and map scale are comparable. A convex slope becomes steeper downslope, while a concave slope becomes gentler downslope. Closed contours can indicate a hill or depression, so inspect height labels and any depression markings before deciding. A contour pattern alone should be read with the map's conventions.
To draw a cross-section, place a strip along the required line, mark contour intersections and transfer their elevations to a profile with a stated vertical scale. A greatly exaggerated vertical scale can make gentle slopes look dramatic. Intervisibility asks whether one location can be seen from another, considering intervening terrain. A high point is not automatically visible from every lower point if an even higher ridge lies between them. A profile helps test the line of sight rather than relying only on the end-point heights.
and geographical interpretation
expresses vertical change relative to horizontal distance, in the same units. A rise of 100 m over 2 km gives 100:2,000, simplified to 1:20. State whether you are describing rise or fall along the direction of travel. On a winding road, distinguish distance along the road from straight-line horizontal distance. Contour maps can help explain settlement, transport and land use: a valley may provide a route corridor, while a steep slope can raise construction difficulty. These are possible relationships, not automatic conclusions without examining rivers, resources and human decisions.
Describe drainage using evidence such as channel arrangement, tributary junctions and relief. A dendritic pattern resembles branching tree limbs and often develops where underlying is relatively uniform. A radial pattern can develop around a central highland. Settlement may be nucleated, dispersed or linear, but identify the arrangement before proposing reasons. A line of buildings along a road can reflect access, yet the map may not establish the historical cause. Separate what the map shows from explanations that require additional evidence.
Self-check
At 1:50,000, a road measured as 6 cm is 3 km long. A square 2 cm by 2 cm at that scale represents 1 km by 1 km, so its area is 1 km². A 120 m rise over 3 km gives a of 1:25. Check every conversion by writing the units, and use an approximate statement when the source measurement is approximate. In interpretation questions, refer to named or located evidence from the supplied map. A general geographical fact earns more explanatory value when connected to a visible feature.